University of Minnesota Hydrodynamics | Open Energy Information
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Lauga, Eric
2015-01-01
Bacteria predate plants and animals by billions of years. Today, they are the world's smallest cells yet they represent the bulk of the world's biomass, and the main reservoir of nutrients for higher organisms. Most bacteria can move on their own, and the majority of motile bacteria are able to swim in viscous fluids using slender helical appendages called flagella. Low-Reynolds-number hydrodynamics is at the heart of the ability of flagella to generate propulsion at the micron scale. In fact, fluid dynamic forces impact many aspects of bacteriology, ranging from the ability of cells to reorient and search their surroundings to their interactions within mechanically and chemically-complex environments. Using hydrodynamics as an organizing framework, we review the biomechanics of bacterial motility and look ahead to future challenges.
Eric Lauga
2015-09-07
Bacteria predate plants and animals by billions of years. Today, they are the world's smallest cells yet they represent the bulk of the world's biomass, and the main reservoir of nutrients for higher organisms. Most bacteria can move on their own, and the majority of motile bacteria are able to swim in viscous fluids using slender helical appendages called flagella. Low-Reynolds-number hydrodynamics is at the heart of the ability of flagella to generate propulsion at the micron scale. In fact, fluid dynamic forces impact many aspects of bacteriology, ranging from the ability of cells to reorient and search their surroundings to their interactions within mechanically and chemically-complex environments. Using hydrodynamics as an organizing framework, we review the biomechanics of bacterial motility and look ahead to future challenges.
Colorado State University Hydrodynamics | Open Energy Information
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Pennsylvania State University Hydrodynamics | Open Energy Information
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Hydrodynamics of vegetated channels
Nepf, Heidi
This paper highlights some recent trends in vegetation hydrodynamics, focusing on conditions within channels and spanning spatial scales from individual blades, to canopies or vegetation patches, to the channel reach. At ...
Skew resisting hydrodynamic seal
Conroy, William T. (Pearland, TX); Dietle, Lannie L. (Sugar Land, TX); Gobeli, Jeffrey D. (Houston, TX); Kalsi, Manmohan S. (Houston, TX)
2001-01-01
A novel hydrodynamically lubricated compression type rotary seal that is suitable for lubricant retention and environmental exclusion. Particularly, the seal geometry ensures constraint of a hydrodynamic seal in a manner preventing skew-induced wear and provides adequate room within the seal gland to accommodate thermal expansion. The seal accommodates large as-manufactured variations in the coefficient of thermal expansion of the sealing material, provides a relatively stiff integral spring effect to minimize pressure-induced shuttling of the seal within the gland, and also maintains interfacial contact pressure within the dynamic sealing interface in an optimum range for efficient hydrodynamic lubrication and environment exclusion. The seal geometry also provides for complete support about the circumference of the seal to receive environmental pressure, as compared the interrupted character of seal support set forth in U.S. Pat. Nos. 5,873,576 and 6,036,192 and provides a hydrodynamic seal which is suitable for use with non-Newtonian lubricants.
Vortex-Based Aero- and Hydrodynamic Estimation
Hemati, Maziar Sam
2013-01-01
Vortex-Based Aero- and Hydrodynamic Estimation . . . . . .2 Aero- andbenefit from vortex-based aero- and hydrodynamic estimation.
University of New Hampshire Hydrodynamics | Open Energy Information
AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page on Google Bookmark EERE: Alternative Fuels Data Center Home Page on QA:QA J-E-1 SECTION J APPENDIX ECoop IncIowa (Utility Company) JumpGTZ ClimateFeed JumpAlbertaUniversity of New
On the universal identity in second order hydrodynamics
Sašo Grozdanov; Andrei O. Starinets
2014-12-29
We compute the 't Hooft coupling correction to the infinite coupling expression for the second order transport coefficient $\\lambda_2$ in ${\\cal N}=4$ $SU(N_c)$ supersymmetric Yang-Mills theory at finite temperature in the limit of infinite $N_c$, which originates from the $R^4$ terms in the low energy effective action of the dual type IIB string theory. Using this result, we show that the identity involving the three second order transport coefficients, $2 \\eta \\tau_\\Pi - 4 \\lambda_1 - \\lambda_2 =0$, previously shown by Haack and Yarom to hold universally in relativistic conformal field theories with string dual descriptions to leading order in supergravity approximation, holds also at next to leading order in this theory. We also compute corrections to transport coefficients in a (hypothetical) strongly interacting conformal fluid arising from the generic curvature squared terms in the corresponding dual gravity action (in particular, Gauss-Bonnet action), and show that the identity holds to linear order in the higher-derivative couplings. We discuss potential implications of these results for the near-equilibrium entropy production rate at strong coupling.
Hydrodynamic noise and Bjorken expansion
J. I. Kapusta; B. Müller; M. Stephanov
2012-11-14
Using the Bjorken expansion model we study the effect of intrinsic hydrodynamic noise on the correlations observed in heavy-ion collisions.
Hydrodynamic interactions in colloidal crystals
Weeber, Rudolf
2011-01-01
In dense colloids it is commonly assumed that hydrodynamic interactions do not play a role. However, a found theoretical quantification is often missing. We present computer simulations that are motivated by experiments where a large colloidal particle is dragged through a colloidal crystal. To qualify the influence of long-ranged hydrodynamics, we model the setup by conventional Langevin dynamics simulations and by an improved scheme with limited hydrodynamic interactions. This scheme significantly improves our results and allows to show that hydrodynamics strongly impacts on the development of defects, the crystal regeneration as well as on the jamming behavior.
Load responsive hydrodynamic bearing
Kalsi, Manmohan S. (Houston, TX); Somogyi, Dezso (Sugar Land, TX); Dietle, Lannie L. (Stafford, TX)
2002-01-01
A load responsive hydrodynamic bearing is provided in the form of a thrust bearing or journal bearing for supporting, guiding and lubricating a relatively rotatable member to minimize wear thereof responsive to relative rotation under severe load. In the space between spaced relatively rotatable members and in the presence of a liquid or grease lubricant, one or more continuous ring shaped integral generally circular bearing bodies each define at least one dynamic surface and a plurality of support regions. Each of the support regions defines a static surface which is oriented in generally opposed relation with the dynamic surface for contact with one of the relatively rotatable members. A plurality of flexing regions are defined by the generally circular body of the bearing and are integral with and located between adjacent support regions. Each of the flexing regions has a first beam-like element being connected by an integral flexible hinge with one of the support regions and a second beam-like element having an integral flexible hinge connection with an adjacent support region. A least one local weakening geometry of the flexing region is located intermediate the first and second beam-like elements. In response to application of load from one of the relatively rotatable elements to the bearing, the beam-like elements and the local weakening geometry become flexed, causing the dynamic surface to deform and establish a hydrodynamic geometry for wedging lubricant into the dynamic interface.
Landau Hydrodynamics Reexamined
Cheuk-Yin Wong
2008-11-06
We review the formulation of Landau hydrodynamics and find that the rapidity distribution of produced particles in the center-of-mass system should be more appropriately modified as dN/dy \\exp[\\sqrt{y_b^2-y^2}], where y_b=\\ln[\\sqrt{s_{NN}}/m_p] is the beam nucleon rapidity, instead of Landau's original distribution, dN/dy(Landau) \\exp[\\sqrt{L^2-y^2}], where L=\\ln[\\sqrt{s_{NN}}/2m_p]. The modified distribution agrees better with experimental dN/dy data than the original Landau distribution and can be represented well by the Gaussian distribution, dN/dy(Gaussian) \\exp[-y^2/2L]. Past successes of the Gaussian distribution in explaining experimental rapidity data can be understood, not because it is an approximation of the original Landau distribution, but because it is in fact a close representation of the modified distribution. Predictions for pp and AA collisions at LHC energies in Landau hydrodynamics are presented.
Lectures on Landau Hydrodynamics
Cheuk-Yin Wong
2008-09-02
Landau hydrodynamics is a plausible description for the evolution of the dense hot matter produced in high-energy heavy-ion collisions. We review the formulation of Landau hydrodynamics to pave the way for its application in high-energy heavy-ion collisions. It is found that Landau's rapidity distribution needs to be modified to provide a better quantitative description. In particular, the rapidity distribution in the center-of-mass system should be more appropriately given as dN/dy \\exp{\\sqrt{y_b^2-y^2}}, where y_b=\\ln{\\sqrt{s_NN}/m_p} is the beam nucleon rapidity, instead of Landau's original result of dN/dy({Landau}) \\exp{\\sqrt{L^2-y^2}} where L=\\ln{\\sqrt{s_NN}/2m_p}. The modified distribution is compared with the Landau distribution and experimental data. It is found that the modified distribution agrees better with experimental $dN/dy$ data than the Landau distribution and it differs only slightly from the Landau Gaussian distribution dN/dy(Landau-Gaussian) \\exp{-y^2/2L}. Past successes of the Gaussian distribution in explaining experimental rapidity data arises, not because it is an approximation of the original Landau distribution, but because it is in fact a close representation of the modified distribution.
Lifshitz Superfluid Hydrodynamics
Shira Chapman; Carlos Hoyos; Yaron Oz
2014-10-09
We construct the first order hydrodynamics of quantum critical points with Lifshitz scaling and a spontaneously broken symmetry. The fluid is described by a combination of two flows, a normal component that carries entropy and a super-flow which has zero viscosity and carries no entropy. We analyze the new transport effects allowed by the lack of boost invariance and constrain them by the local second law of thermodynamics. Imposing time-reversal invariance, we find eight new parity even transport coefficients. The formulation is applicable, in general, to any superfluid/superconductor with an explicit breaking of boost symmetry, in particular to high $T_c$ superconductors. We discuss possible experimental signatures.
An implicit numerical algorithm general relativistic hydrodynamics
A. Hujeirat
2008-01-09
An implicit numerical algorithm general relativistic hydrodynamics This article has been replaced by arXiv:0801.1017
Millifluidics: Capillarity and Interfacial Hydrodynamics
Bico,José
Millifluidics: Capillarity and Interfacial Hydrodynamics José Bico PMMH-ESPCI-ParisTech-P6-P7 www Pa ~ 10-2 atm cavitation bubble: R ~ 0.5 !m, # ~ 50 mN/m $P ~ 105 Pa ~ 1 atm He bubbles (irradiated
Topological groundwater hydrodynamics Garrison Sposito
Chen, Yiling
Topological groundwater hydrodynamics Garrison Sposito Department of Civil and Environmental; received in revised form 10 November 2000; accepted 15 November 2000 Abstract Topological groundwater, the topological characteristics of groundwater ¯ows governed by the Darcy law are studied. It is demonstrated that
Hydrodynamic Lyapunov Modes in Translation Invariant Systems
Hydrodynamic Lyapunov Modes in Translation Invariant Systems JeanÂPierre Eckmann and Omri Gat De modes in the slowly growing part of the Lyapunov spectrum, which are analogous to the hydrodynamic modes)]. The hydrodynamic Lyapunov vectors loose the typical random structure and exhibit instead the structure of weakly
Hydrodynamic Lyapunov Modes in Translation Invariant Systems
Eckmann, Jean-Pierre
Hydrodynamic Lyapunov Modes in Translation Invariant Systems JeanPierre Eckmann and Omri Gat De modes in the slowly growing part of the Lyapunov spectrum, which are analogous to the hydrodynamic modes)]. The hydrodynamic Lyapunov vectors loose the typical random structure and exhibit instead the structure of weakly
Some open questions in hydrodynamics
Mateusz Dyndal; Laurent Schoeffel
2014-12-16
When speaking of unsolved problems in physics, this is surprising at first glance to discuss the case of fluid mechanics. However, there are many deep open questions that come with the theory of fluid mechanics. In this paper, we discuss some of them that we classify in two categories, the long term behavior of solutions of equations of hydrodynamics and the definition of initial (boundary) conditions. The first set of questions come with the non-relativistic theory based on the Navier-Stokes equations. Starting from smooth initial conditions, the purpose is to understand if solutions of Navier-Stokes equations remain smooth with the time evolution. Existence for just a finite time would imply the evolution of finite time singularities, which would have a major influence on the development of turbulent phenomena. The second set of questions come with the relativistic theory of hydrodynamics. There is an accumulating evidence that this theory may be relevant for the description of the medium created in high energy heavy-ion collisions. However, this is not clear that the fundamental hypotheses of hydrodynamics are valid in this context. Also, the determination of initial conditions remains questionable. The purpose of this paper is to explore some ideas related to these questions, both in the non-relativistic and relativistic limits of fluid mechanics. We believe that these ideas do not concern only the theory side but can also be useful for interpreting results from experimental measurements.
Foundation of Hydrodynamics of Strongly Interacting Systems
Cheuk-Yin Wong
2014-04-03
Hydrodynamics and quantum mechanics have many elements in common, as the density field and velocity fields are common variables that can be constructed in both descriptions. Starting with the Schroedinger equation and the Klein-Gordon for a single particle in hydrodynamical form, we examine the basic assumptions under which a quantum system of particles interacting through their mean fields can be described by hydrodynamics.
Foundation of Hydrodynamics of Strongly Interacting Systems
Wong, Cheuk-Yin
2014-01-01
Hydrodynamics and quantum mechanics have many elements in common, as the density field and velocity fields are common variables that can be constructed in both descriptions. Starting with the Schroedinger equation and the Klein-Gordon for a single particle in hydrodynamical form, we examine the basic assumptions under which a quantum system of particles interacting through their mean fields can be described by hydrodynamics.
Annual Report: Hydrodynamics and Radiative Hydrodynamics with Astrophysical Applications
R. Paul Drake
2005-12-01
We report the ongoing work of our group in hydrodynamics and radiative hydrodynamics with astrophysical applications. During the period of the existing grant, we have carried out two types of experiments at the Omega laser. One set of experiments has studied radiatively collapsing shocks, obtaining high-quality scaling data using a backlit pinhole and obtaining the first (ever, anywhere) Thomson-scattering data from a radiative shock. Other experiments have studied the deeply nonlinear development of the Rayleigh-Taylor (RT) instability from complex initial conditions, obtaining the first (ever, anywhere) dual-axis radiographic data using backlit pinholes and ungated detectors. All these experiments have applications to astrophysics, discussed in the corresponding papers either in print or in preparation. We also have obtained preliminary radiographs of experimental targets using our x-ray source. The targets for the experiments have been assembled at Michigan, where we also prepare many of the simple components. The above activities, in addition to a variety of data analysis and design projects, provide good experience for graduate and undergraduates students. In the process of doing this research we have built a research group that uses such work to train junior scientists.
Dual Axis Radiographic Hydrodynamic Test Facility | National...
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Dual Axis Radiographic Hydrodynamic Test Facility | National Nuclear Security Administration Facebook Twitter Youtube Flickr RSS People Mission Managing the Stockpile Preventing...
Effects on the Physical Environment (Hydrodynamics, Sediment...
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Sediment Transport, and Water Quality) Effects on the Physical Environment (Hydrodynamics, Sediment Transport, and Water Quality) Effects on the Physical Environment...
COMBINED MODELING OF ACCELERATION, TRANSPORT, AND HYDRODYNAMIC...
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COMBINED MODELING OF ACCELERATION, TRANSPORT, AND HYDRODYNAMIC RESPONSE IN SOLAR FLARES. I. THE NUMERICAL MODEL Citation Details In-Document Search Title: COMBINED MODELING OF...
Notes 00. Introduction to Hydrodynamic Lubrication
San Andres, Luis
2010-01-01
The basic laws of friction. Fluid Film Bearings. Basic Operational Principles. Hydrodynamic and Hydrostatic Bearing Configurations. Example of rotordynamic study. Performance objectives....
Collision-dominated nonlinear hydrodynamics in graphene
Briscot, U; Gornyi, I V; Titov, M; Narozhny, B N; Mirlin, A D
2015-01-01
We present an effective hydrodynamic theory of electronic transport in graphene in the interaction-dominated regime. We derive the emergent hydrodynamic description from the microscopic Boltzmann kinetic equation taking into account dissipation due to Coulomb interaction and find the viscosity of Dirac fermions in graphene for arbitrary densities. The viscous terms have a dramatic effect on transport coefficients in clean samples at high temperatures. Within linear response, we show that viscosity manifests itself in the nonlocal conductivity as well as dispersion of hydrodynamic plasmons. Beyond linear response, we apply the derived nonlinear hydrodynamics to the problem of hot spot relaxation in graphene.
Disruptive Innovation in Numerical Hydrodynamics
Waltz, Jacob I.
2012-09-06
We propose the research and development of a high-fidelity hydrodynamic algorithm for tetrahedral meshes that will lead to a disruptive innovation in the numerical modeling of Laboratory problems. Our proposed innovation has the potential to reduce turnaround time by orders of magnitude relative to Advanced Simulation and Computing (ASC) codes; reduce simulation setup costs by millions of dollars per year; and effectively leverage Graphics Processing Unit (GPU) and future Exascale computing hardware. If successful, this work will lead to a dramatic leap forward in the Laboratory's quest for a predictive simulation capability.
Hydrodynamics on non-commutative space --A step toward hydrodynamics of granular materials--
Mayumi Saitou; Kazuharu Bamba; Akio Sugamoto
2014-09-16
Hydrodynamics on non-commutative space is studied based on a formulation of hydrodynamics by Y. Nambu in terms of Poisson and Nambu brackets. Replacing these brackets by Moyal brackets with a parameter $\\theta$, a new hydrodynamics on non-commutative space is derived. It may be a step toward to find the hydrodynamics of granular materials whose minimum volume is given by $\\theta$. To clarify this minimum volume, path integral quantization and uncertainty relation of Nambu dynamics are examined.
Hydrodynamics and phases of flocks
Toner, John [Institute of Theoretical Science, Department of Physics, University of Oregon, Eugene, OR 97403-5203 (United States); Tu Yuhai [IBM T. J. Watson Research Center, P.O. Box 218, Yorktown Heights, NY 10598 (United States)]. E-mail: yuhai@us.ibm.com; Ramaswamy, Sriram [Centre for Condensed Matter Theory, Department of Physics, Indian Institute of Science, Bangalore 560012 (India)
2005-07-01
We review the past decade's theoretical and experimental studies of flocking: the collective, coherent motion of large numbers of self-propelled 'particles' (usually, but not always, living organisms). Like equilibrium condensed matter systems, flocks exhibit distinct 'phases' which can be classified by their symmetries. Indeed, the phases that have been theoretically studied to date each have exactly the same symmetry as some equilibrium phase (e.g., ferromagnets, liquid crystals). This analogy with equilibrium phases of matter continues in that all flocks in the same phase, regardless of their constituents, have the same 'hydrodynamic'-that is, long-length scale and long-time behavior, just as, e.g., all equilibrium fluids are described by the Navier-Stokes equations. Flocks are nonetheless very different from equilibrium systems, due to the intrinsically nonequilibrium self-propulsion of the constituent 'organisms'. This difference between flocks and equilibrium systems is most dramatically manifested in the ability of the simplest phase of a flock, in which all the organisms are, on average moving in the same direction (we call this a 'ferromagnetic' flock; we also use the terms 'vector-ordered' and 'polar-ordered' for this situation) to exist even in two dimensions (i.e., creatures moving on a plane), in defiance of the well-known Mermin-Wagner theorem of equilibrium statistical mechanics, which states that a continuous symmetry (in this case, rotation invariance, or the ability of the flock to fly in any direction) can not be spontaneously broken in a two-dimensional system with only short-ranged interactions. The 'nematic' phase of flocks, in which all the creatures move preferentially, or are simply oriented preferentially, along the same axis, but with equal probability of moving in either direction, also differs dramatically from its equilibrium counterpart (in this case, nematic liquid crystals). Specifically, it shows enormous number fluctuations, which actually grow with the number of organisms faster than the N 'law of large numbers' obeyed by virtually all other known systems. As for equilibrium systems, the hydrodynamic behavior of any phase of flocks is radically modified by additional conservation laws. One such law is conservation of momentum of the background fluid through which many flocks move, which gives rise to the 'hydrodynamic backflow' induced by the motion of a large flock through a fluid. We review the theoretical work on the effect of such background hydrodynamics on three phases of flocks-the ferromagnetic and nematic phases described above, and the disordered phase in which there is no order in the motion of the organisms. The most surprising prediction in this case is that 'ferromagnetic' motion is always unstable for low Reynolds-number suspensions. Experiments appear to have seen this instability, but a quantitative comparison is awaited. We conclude by suggesting further theoretical and experimental work to be done.
Hydrodynamic enhanced dielectrophoretic particle trapping
Miles, Robin R.
2003-12-09
Hydrodynamic enhanced dielectrophoretic particle trapping carried out by introducing a side stream into the main stream to squeeze the fluid containing particles close to the electrodes producing the dielelectrophoretic forces. The region of most effective or the strongest forces in the manipulating fields of the electrodes producing the dielectrophoretic forces is close to the electrodes, within 100 .mu.m from the electrodes. The particle trapping arrangement uses a series of electrodes with an AC field placed between pairs of electrodes, which causes trapping of particles along the edges of the electrodes. By forcing an incoming flow stream containing cells and DNA, for example, close to the electrodes using another flow stream improves the efficiency of the DNA trapping.
Increasing Hydrodynamic Efficiency by Reducing Cross-Beam Energy...
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Increasing Hydrodynamic Efficiency by Reducing Cross-Beam Energy Transfer in Direct-Drive-Implosion Experiments Citation Details In-Document Search Title: Increasing Hydrodynamic...
NOAA Fisheries Protocols For Hydro-dynamic Dredge Surveys
NOAA Fisheries Protocols For Hydro-dynamic Dredge Surveys: Surf Clams and Ocean Quahogs December 19..................................................................................................................................... 1 NOAA Fisheries Hydro-dynamic Clam Dredge Survey Protocols
Effects on the Physical Environment (Hydrodynamics, and Water...
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and Water Quality Food Web) Effects on the Physical Environment (Hydrodynamics, and Water Quality Food Web) Effects on the Physical Environment (Hydrodynamics, and Water Quality...
Hydrodynamic interactions in metal rod-like particle suspensions...
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Journal Article: Hydrodynamic interactions in metal rod-like particle suspensions due to induced charge electroosmosis Citation Details In-Document Search Title: Hydrodynamic...
DARHT: Dual-Axis Radiographic Hydrodynamic Test Facility
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DARHT: Dual-Axis Radiographic Hydrodynamic Test Facility DARHT: Dual-Axis Radiographic Hydrodynamic Test Facility DARHT, supports a critical component of LANL's primary mission: to...
MHD duct flows under hydrodynamic “slip” condition
Smolentsev, S.
2009-01-01
two-dimensional turbulence in MHD duct ?ows, CTR, Stanfordow in rectangular ducts. J. Fluid Mech. 21, 577–590 (1965)C L E S. Smolentsev MHD duct ?ows under hydrodynamic “slip”
Shear viscosity, cavitation and hydrodynamics at LHC
Bhatt, Jitesh R; Sreekanth, V
2011-01-01
We study evolution of quark-gluon matter in the ultrarelativistic heavy-ion collisions within the frame work of relativistic second-order viscous hydrodynamics. In particular, by using the various prescriptions of a temperature-dependent shear viscosity to the entropy ratio, we show that the hydrodynamic description of the relativistic fluid become invalid due to the phenomenon of cavitation. For most of the initial conditions relevant for LHC, the cavitation sets in very early during the evolution of the hydrodynamics in time $\\lesssim 2 $fm/c. The cavitation in this case is entirely driven by the large values of shear viscosity. Moreover we also demonstrate that the conformal term used in equations of the relativistic dissipative hydrodynamic can influence the cavitation time.
Shear viscosity, cavitation and hydrodynamics at LHC
Jitesh R. Bhatt; Hiranmaya Mishra; V. Sreekanth
2011-09-28
We study evolution of quark-gluon matter in the ultrarelativistic heavy-ion collisions within the frame work of relativistic second-order viscous hydrodynamics. In particular, by using the various prescriptions of a temperature-dependent shear viscosity to the entropy ratio, we show that the hydrodynamic description of the relativistic fluid become invalid due to the phenomenon of cavitation. For most of the initial conditions relevant for LHC, the cavitation sets in very early during the evolution of the hydrodynamics in time $\\lesssim 2 $fm/c. The cavitation in this case is entirely driven by the large values of shear viscosity. Moreover we also demonstrate that the conformal term used in equations of the relativistic dissipative hydrodynamic can influence the cavitation time.
General Relativistic Hydrodynamics on Overlapping Curvilinear Grids
Blakely, P. M.; Nikiforakis, N.; Henshaw, W. D.
2015-03-04
the simplification of the equation for conservation of energy and momentum, T ??;? = 0, to the linear wave equation ?;? ? = 0 (although we note that not all solutions of the linear wave equation result in physically valid stiff-fluid solutions). 2.2. Ideal fluid... disks – hydrodynamics – shock waves 1. Introduction The simulation of general relativistic hydrodynamical (GRHD) problems is of great importance to the astrophysics commu- nity. Although special relativistic and post Newtonian approx- imations can...
Non-hydrodynamic transport in trapped unitary Fermi gases
Jasmine Brewer; Paul Romatschke
2015-08-05
Many strongly coupled fluids are known to share similar hydrodynamic transport properties. In this work we argue that this similarity could extend beyond hydrodynamics to transient dynamics through the presence of non-hydrodynamic modes. We review non-hydrodynamic modes in kinetic theory and gauge/gravity duality and discuss their signatures in trapped Fermi gases close to unitarity. Reanalyzing previously published experimental data, we find hints of non-hydrodynamic modes in cold Fermi gases in two and three dimensions.
Non-hydrodynamic transport in trapped unitary Fermi gases
Brewer, Jasmine
2015-01-01
Many strongly coupled fluids are known to share similar hydrodynamic transport properties. In this work we argue that this similarity could extend beyond hydrodynamics to transient dynamics through the presence of non-hydrodynamic modes. We review non-hydrodynamic modes in kinetic theory and gauge/gravity duality and discuss their signatures in trapped Fermi gases close to unitarity. Reanalyzing previously published experimental data, we find hints of non-hydrodynamic modes in cold Fermi gases in two and three dimensions.
On the hydrodynamics of swimming enzymes
Xiaoyu Bai; Peter G. Wolynes
2015-10-07
Several recent experiments suggest that rather generally the diffusion of enzymes may be augmented through their activity. We demonstrate that such swimming motility can emerge from the interplay between the enzyme energy landscape and the hydrodynamic coupling of the enzyme to its environment. Swimming thus occurs during the transit time of a transient allosteric change. We estimate the velocity during the transition. The analysis of such a swimming motion suggests the final stroke size is limited by the hydrodynamic size of the enzyme. This limit is quite a bit smaller than the values that can be inferred from the recent experiments. We also show that one proposed explanation of the experiments based on reaction heat effects can be ruled out using an extended hydrodynamic analysis. These results lead us to propose an alternate explanation of the fluorescence correlation measurements.
A powerful hydrodynamic booster for relativistic jets
Miguel A. Aloy; Luciano Rezzolla
2006-02-20
Velocities close to the speed of light are a robust observational property of the jets observed in microquasars and AGNs, and are expected to be behind much of the phenomenology of GRBs. Yet, the mechanism boosting relativistic jets to such large Lorentz factors is still essentially unknown. Building on recent general-relativistic, multidimensional simulations of progenitors of short GRBs, we discuss a new effect in relativistic hydrodynamics which can act as an efficient booster in jets. This effect is purely hydrodynamical and occurs when large velocities tangential to a discontinuity are present in the flow, yielding Lorentz factors $\\Gamma \\sim 10^2-10^3$ or larger in flows with moderate initial Lorentz factors. Although without a Newtonian counterpart, this effect can be explained easily through the most elementary hydrodynamical flow: i.e., a relativistic Riemann problem.
Parity Breaking Transport in Lifshitz Hydrodynamics
Carlos Hoyos; Adiel Meyer; Yaron Oz
2015-08-31
We derive the constitutive relations of first order charged hydrodynamics for theories with Lifshitz scaling and broken parity in $2+1$ and $3+1$ spacetime dimensions. In addition to the anomalous (in $3+1$) or Hall (in $2+1$) transport of relativistic hydrodynamics, there is an additional non-dissipative transport allowed by the absence of boost invariance. We analyze the non-relativistic limit and use a phenomenological model of a strange metal to argue that these effects can be measured in principle by using electromagnetic fields with non-zero gradients.
Bounce-free spherical hydrodynamic implosion
Kagan, Grigory; Tang Xianzhu; Hsu, Scott C.; Awe, Thomas J. [Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)
2011-12-15
In a bounce-free spherical hydrodynamic implosion, the post-stagnation hot core plasma does not expand against the imploding flow. Such an implosion scheme has the advantage of improving the dwell time of the burning fuel, resulting in a higher fusion burn-up fraction. The existence of bounce-free spherical implosions is demonstrated by explicitly constructing a family of self-similar solutions to the spherically symmetric ideal hydrodynamic equations. When applied to a specific example of plasma liner driven magneto-inertial fusion, the bounce-free solution is found to produce at least a factor of four improvement in dwell time and fusion energy gain.
Physical and Hydrodynamic Properties of Flocs Produced During Biological
Physical and Hydrodynamic Properties of Flocs Produced During Biological Hydrogen Production Jian in continuous culture bioreactors used for hydrogen production, but the fractal and hydrodynamic properties imperme- able flocs are produced in biohydrogen reactors that have settling properties in reasonable
General Relativity as Geometro-Hydrodynamics
B. L. Hu
1996-07-29
In the spirit of Sakharov's `metric elasticity' proposal, we draw a loose analogy between general relativity and the hydrodynamic state of a quantum gas. In the `top-down' approach, we examine the various conditions which underlie the transition from some candidate theory of quantum gravity to general relativity. Our emphasis here is more on the `bottom-up' approach, where one starts with the semiclassical theory of gravity and examines how it is modified by graviton and quantum field excitations near and above the Planck scale. We mention three aspects based on our recent findings: 1) Emergence of stochastic behavior of spacetime and matter fields depicted by an Einstein-Langevin equation. The backreaction of quantum fields on the classical background spacetime manifests as a fluctuation-dissipation relation. 2) Manifestation of stochastic behavior in effective theories below the threshold arising from excitations above. The implication for general relativity is that such Planckian effects, though exponentially suppressed, is in principle detectable at sub-Planckian energies. 3) Decoherence of correlation histories and quantum to classical transition. From Gell-Mann and Hartle's observation that the hydrodynamic variables which obey conservation laws are most readily decohered, one can, in the spirit of Wheeler, view the conserved Bianchi identity obeyed by the Einstein tensor as an indication that general relativity is a hydrodynamic theory of geometry. Many outstanding issues surrounding the transition to general relativity are of a nature similar to hydrodynamics and mesoscopic physics.
Dilepton production in schematic causal viscous hydrodynamics
Song, Taesoo; Han, Kyong Chol; Ko, Che Ming.
2011-01-01
transversal to the reaction plane, we derive a set of schematic equations from the Isreal-Stewart causal viscous hydrodynamics. These equations are then used to describe the evolution dynamics of relativistic heavy-ion collisions by taking the shear viscosity...
HYDRODYNAMICS OF UNDULATORY PROPULSION GEORGE V. LAUDER
Lauder, George V.
of a quantitative nature. The combination of highresolution highspeed video systems, high powered continuous wave11 HYDRODYNAMICS OF UNDULATORY PROPULSION GEORGE V. LAUDER ERIC D. TYTELL I. Introduction II. Classical Modes of Undulatory Propulsion III. Theory of Undulatory Propulsion A. Resistive Models B
Stabilizing geometry for hydrodynamic rotary seals
Dietle, Lannie L. (Houston, TX); Schroeder, John E. (Richmond, TX)
2010-08-10
A hydrodynamic sealing assembly including a first component having first and second walls and a peripheral wall defining a seal groove, a second component having a rotatable surface relative to said first component, and a hydrodynamic seal comprising a seal body of generally ring-shaped configuration having a circumference. The seal body includes hydrodynamic and static sealing lips each having a cross-sectional area that substantially vary in time with each other about the circumference. In an uninstalled condition, the seal body has a length defined between first and second seal body ends which varies in time with the hydrodynamic sealing lip cross-sectional area. The first and second ends generally face the first and second walls, respectively. In the uninstalled condition, the first end is angulated relative to the first wall and the second end is angulated relative to the second wall. The seal body has a twist-limiting surface adjacent the static sealing lip. In the uninstalled condition, the twist-limiting surface is angulated relative to the peripheral wall and varies along the circumference. A seal body discontinuity and a first component discontinuity mate to prevent rotation of the seal body relative to the first component.
Adiabatic hydrodynamics: The eightfold way to dissipation
Felix M. Haehl; R. Loganayagam; Mukund Rangamani
2015-03-17
We provide a complete solution to hydrodynamic transport at all orders in the gradient expansion compatible with the second law constraint. The key new ingredient we introduce is the notion of adiabaticity, which allows us to take hydrodynamics off-shell. Adiabatic fluids are such that off-shell dynamics of the fluid compensates for entropy production. The space of adiabatic fluids is quite rich, and admits a decomposition into seven distinct classes. Together with the dissipative class this establishes the eightfold way of hydrodynamic transport. Furthermore, recent results guarantee that dissipative terms beyond leading order in the gradient expansion are agnostic of the second law. While this completes a transport taxonomy, we go on to argue for a new symmetry principle, an Abelian gauge invariance that guarantees adiabaticity in hydrodynamics. We suggest that this symmetry is the macroscopic manifestation of the microscopic KMS invariance. We demonstrate its utility by explicitly constructing effective actions for adiabatic transport. The theory of adiabatic fluids, we speculate, provides a useful starting point for a new framework to describe non-equilibrium dynamics, wherein dissipative effects arise by Higgsing the Abelian symmetry.
Hydrodynamic Flow Patterns and Synchronization of Beating Cilia Andrej Vilfan*
Jülicher, Frank
Hydrodynamic Flow Patterns and Synchronization of Beating Cilia Andrej Vilfan* J. Stefan Institute 2006) We calculate the hydrodynamic flow field generated far from a cilium which is attached to a surface and beats periodically. In the case of two beating cilia, hydrodynamic interactions can lead
Vacuum energy: quantum hydrodynamics vs quantum gravity
G. E. Volovik
2005-09-09
We compare quantum hydrodynamics and quantum gravity. They share many common features. In particular, both have quadratic divergences, and both lead to the problem of the vacuum energy, which in the quantum gravity transforms to the cosmological constant problem. We show that in quantum liquids the vacuum energy density is not determined by the quantum zero-point energy of the phonon modes. The energy density of the vacuum is much smaller and is determined by the classical macroscopic parameters of the liquid including the radius of the liquid droplet. In the same manner the cosmological constant is not determined by the zero-point energy of quantum fields. It is much smaller and is determined by the classical macroscopic parameters of the Universe dynamics: the Hubble radius, the Newton constant and the energy density of matter. The same may hold for the Higgs mass problem: the quadratically divergent quantum correction to the Higgs potential mass term is also cancelled by the microscopic (trans-Planckian) degrees of freedom due to thermodynamic stability of the whole quantum vacuum.
Effective Hydrodynamic Boundary Conditions for Corrugated Surfaces
Mongruel, Anne; Asmolov, Evgeny S; Vinogradova, Olga I
2012-01-01
We report measurements of the hydrodynamic drag force acting on a smooth sphere falling down under gravity to a plane decorated with microscopic periodic grooves. Both surfaces are lyophilic, so that a liquid (silicone oil) invades the surface texture being in the Wenzel state. A significant decrease in the hydrodynamic resistance force as compared with that predicted for two smooth surfaces is observed. To quantify the effect of roughness we use the effective no-slip boundary condition, which is applied at the imaginary smooth homogeneous isotropic surface located at an intermediate position between top and bottom of grooves. Such an effective condition fully characterizes the force reduction measured with the real surface, and the location of this effective plane is related to geometric parameters of the texture by a simple analytical formula.
Heat capacity of liquids: A hydrodynamic approach
T. Bryk; T. Scopigno; G. Ruocco
2015-04-06
We study autocorrelation functions of energy, heat and entropy densities obtained by molecular dynamics simulations of supercritical Ar and compare them with the predictions of the hydrodynamic theory. It is shown that the predicted by the hydrodynamic theory single-exponential shape of the entropy density autocorrelation functions is perfectly reproduced for small wave numbers by the molecular dynamics simulations and permits the calculation of the wavenumber-dependent specific heat at constant pressure. The estimated wavenumber-dependent specific heats at constant volume and pressure, $C_{v}(k)$ and $C_{p}(k)$, are shown to be in the long-wavelength limit in good agreement with the macroscopic experimental values of $C_{v}$ and $C_{p}$ for the studied thermodynamic points of supercritical Ar.
Hydrodynamic Interactions of Self-Propelled Swimmers
John J. Molina; Yasuya Nakayama; Ryoichi Yamamoto
2013-01-12
The hydrodynamic interactions of a suspension of self-propelled particles are studied using a direct numerical simulation method which simultaneously solves for the host fluid and the swimming particles. A modified version of the "Smoothed Profile" method (SPM) is developed to simulate microswimmers as squirmers, which are spherical particles with a specified surface-tangential slip velocity between the particles and the fluid. This simplified swimming model allows one to represent different types of propulsion (pullers and pushers) and is thus ideal to study the hydrodynamic interactions among swimmers. We use the SPM to study the diffusive behavior which arises due to the swimming motion of the particles, and show that there are two basic mechanisms responsible for this phenomena: the hydrodynamic interactions caused by the squirming motion of the particles, and the particle-particle collisions. This dual nature gives rise to two distinct time- and length- scales, and thus to two diffusion coefficients, which we obtain by a suitable analysis of the swimming motion. We show that the collisions between swimmers can be interpreted in terms of binary collisions, in which the effective collision radius is reduced due to the collision dynamics of swimming particles in viscous fluids. At short time-scales, the dynamics of the swimmer is analogous to that of an inert tracer particle in a swimming suspension, in which the diffusive motion is caused by fluid-particle collisions. Our results, along with the simulation method we have introduced, will allow us to gain a better understanding of the complex hydrodynamic interactions of self-propelled swimmers.
HydrodynamicallyBased Overshoot Treatment and Nucleosynthesis
HydrodynamicallyÂBased Overshoot Treatment and Nucleosynthesis in AGB Stars F. Herwig 1 , T. Bl dominated by 12 C. This leads to the nucleosynthesis of 13 C via 12 C(p; fl) 13 N(fi; + Å¡) 13 C and is probÂ ably the major source of neutrons ( 13 C(ff; n) 16 O) for subsequent sÂprocess nucleosynthesis. We
Consistent description of kinetics and hydrodynamics of dusty plasma
Markiv, B.; Tokarchuk, M.; National University “Lviv Polytechnic,” 12 Bandera St., 79013 Lviv
2014-02-15
A consistent statistical description of kinetics and hydrodynamics of dusty plasma is proposed based on the Zubarev nonequilibrium statistical operator method. For the case of partial dynamics, the nonequilibrium statistical operator and the generalized transport equations for a consistent description of kinetics of dust particles and hydrodynamics of electrons, ions, and neutral atoms are obtained. In the approximation of weakly nonequilibrium process, a spectrum of collective excitations of dusty plasma is investigated in the hydrodynamic limit.
Longitudinal Viscous Hydrodynamic Evolution for the Shattered Colour Glass Condensate
Akihiko Monnai; Tetsufumi Hirano
2011-02-24
We investigate hydrodynamic evolution of the quark gluon plasma for the colour glass condensate type initial conditions. We solve full second-order viscous hydrodynamic equations in the longitudinal direction to find that non-boost invariant expansion leads to visible deformation on the initial rapidity distribution. The results indicate that hydrodynamic evolution with viscosity plays an important role in determining parameters for the initial distributions.
13.024 Numerical Marine Hydrodynamics, Spring 2003
Milgram, Jerome H.
Introduction to numerical methods: interpolation, differentiation, integration, systems of linear equations. Solution of differential equations by numerical integration, partial differential equations of inviscid hydrodynamics: ...
Assessing Thermo-Hydrodynamic-Chemical Processes at the Dixie...
Sainsbury,Joe Iovenitti,B. Mack Kennedy. 2013. Assessing Thermo-Hydrodynamic-Chemical Processes at the Dixie Valley Geothermal Area- A Reactive Transport Modeling...
Compressible hydrodynamic flow of liquid crystals in 1-D
2009-08-17
We consider the equation modeling the compressible hydrodynamic flow ... In this paper, we consider the one dimensional initial-boundary value problem for.
Particle-Based Mesoscale Hydrodynamic Techniques
Hiroshi Noguchi; Norio Kikuchi; Gerhard Gompper
2006-10-31
Dissipative particle dynamics (DPD) and multi-particle collision (MPC) dynamics are powerful tools to study mesoscale hydrodynamic phenomena accompanied by thermal fluctuations. To understand the advantages of these types of mesoscale simulation techniques in more detail, we propose new two methods, which are intermediate between DPD and MPC -- DPD with a multibody thermostat (DPD-MT), and MPC-Langevin dynamics (MPC-LD). The key features are applying a Langevin thermostat to the relative velocities of pairs of particles or multi-particle collisions, and whether or not to employ collision cells. The viscosity of MPC-LD is derived analytically, in very good agreement with the results of numerical simulations.
Hydrodynamic Testing Facilities Database | Open Energy Information
AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page on Google Bookmark EERE: Alternative Fuels Data Center Home Page on QA:QAsource History View NewTexas: Energy Resources JumpNewTexas: EnergyHunterdonHutto,Fuel CellHydrodynamic Testing
Hydrodynamic Testing Facilities Database | Open Energy Information
AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page on Google Bookmark EERE: Alternative Fuels Data Center Home Page on QA:QA J-E-1 SECTION J APPENDIX E LIST OFAMERICA'SHeavy ElectricalsFTLTechnology SrlWindHydrodynamic Testing Facilities
Supernova Hydrodynamics on the Omega Laser
R. Paul Drake
2004-01-16
(B204)The fundamental motivation for our work is that supernovae are not well understood. Recent observations have clarified the depth of our ignorance, by producing observed phenomena that current theory and computer simulations cannot reproduce. Such theories and simulations involve, however, a number of physical mechanisms that have never been studied in isolation. We perform experiments, in compressible hydrodynamics and radiation hydrodynamics, relevant to supernovae and supernova remnants. These experiments produce phenomena in the laboratory that are believed, based on simulations, to be important to astrophysics but that have not been directly observed in either the laboratory or in an astrophysical system. During the period of this grant, we have focused on the scaling of an astrophysically relevant, radiative-precursor shock, on preliminary studies of collapsing radiative shocks, and on the multimode behavior and the three-dimensional, deeply nonlinear evolution of the Rayleigh-Taylor (RT) instability at a decelerating, embedded interface. These experiments required strong compression and decompression, strong shocks (Mach {approx}10 or greater), flexible geometries, and very smooth laser beams, which means that the 60-beam Omega laser is the only facility capable of carrying out this program.
Technical Report 2010-2 Smoothed Particle Hydrodynamics in Acoustic
Negrut, Dan
and architectural acoustics can be addressed by solving the linear wave equation with an appropriate numericalTechnical Report 2010-2 Smoothed Particle Hydrodynamics in Acoustic Simulations Philipp Hahn, Dan Lagrangian technique, called Smoothed Particle Hydrodynamics (SPH), as a method for acoustic simulation
RESEARCH ARTICLE Hydrodynamic sensing and behavior by oyster larvae in
Fuchs, Heidi L.
were achieved through an increase in propulsive force and power output that would carry a highRESEARCH ARTICLE Hydrodynamic sensing and behavior by oyster larvae in turbulence and waves Heidi L Hydrodynamic signals from turbulence and waves may provide marine invertebrate larvae with behavioral cues
LINEAR STABILITY OF ELECTRON-FLOW HYDRODYNAMICS IN UNGATED SEMICONDUCTORS
Sen, Mihir
LINEAR STABILITY OF ELECTRON-FLOW HYDRODYNAMICS IN UNGATED SEMICONDUCTORS A Dissertation Submitted All Rights Reserved #12;LINEAR STABILITY OF ELECTRON-FLOW HYDRODYNAMICS IN UNGATED SEMICONDUCTORS Abstract by Williams R. CalderÂ´on Mu~noz Semiconductors play an important role in modern electronic
Hydrodynamic Tesla Wheel Flume for Model and Prototype Testing
Wood, Stephen L.
The Tesla turbine, U.S. Patent 1,061,206 -- May 6, 1913 was invented by Nikola Tesla as a means to extractHydrodynamic Tesla Wheel Flume for Model and Prototype Testing Spencer Jenkins, Chris Scott, Jacob Engineering department at Florida Institute of Technology (Florida Tech) has developed a Hydrodynamic Tesla
Hydrodynamical random walker with chemotactic memory
H. Mohammady; B. Esckandariun; A. Najafi
2014-10-01
A three-dimensional hydrodynamical model for a micro random walker is combined with the idea of chemotactic signaling network of E. coli. Diffusion exponents, orientational correlation functions and their dependence on the geometrical and dynamical parameters of the system are analyzed numerically. Because of the chemotactic memory, the walker shows superdiffusing displacements in all directions with the largest diffusion exponent for a direction along the food gradient. Mean square displacements and orientational correlation functions show that the chemotactic memory washes out all the signatures due to the geometrical asymmetry of the walker and statistical properties are asymmetric only with respect to the direction of food gradient. For different values of the memory time, the Chemotactic index (CI) is also calculated.
An Owner's Guide to Smoothed Particle Hydrodynamics
T. J. Martin; F. R. Pearce; P. A. Thomas
1993-10-13
We present a practical guide to Smoothed Particle Hydrodynamics (\\SPH) and its application to astrophysical problems. Although remarkably robust, \\SPH\\ must be used with care if the results are to be meaningful since the accuracy of \\SPH\\ is sensitive to the arrangement of the particles and the form of the smoothing kernel. In particular, the initial conditions for any \\SPH\\ simulation must consist of particles in dynamic equilibrium. We describe some of the numerical difficulties that may be encountered when using \\SPH, and how these may be overcome. Through our experience in using \\SPH\\ code to model convective stars, galaxy clusters and large scale structure problems we have developed many diagnostic tests. We give these here as an aid to rapid identification of errors, together with a list of basic prerequisites for the most efficient implementation of \\SPH.
Nonlinear hydrodynamic response confronts LHC data
Yan, Li; Ollitrault, Jean-Yves
2016-01-01
Higher order harmonic flow $v_n$ (with $n\\ge4$) in heavy-ion collisions can be measured either with respect to their own plane, or with respect to a plane constructed using lower-order harmonics. By assuming that higher flow harmonics are the superposition of medium nonlinear and linear responses to initial anisotropies, we propose a set of nonlinear response coefficients $\\chi_n$'s, which are independent of initial state by construction. In experiments, $\\chi_n$'s can be extracted as the ratio between higher order harmonic flow measured in the plane constructed by $v_2$ and $v_3$, and moments of lower order harmonic flow. Simulations with single-shot hydrodynamics and AMPT model lead to results of these nonlinear response coefficients in good agreement with the experimental data at the LHC energy. Predictions for $v_7$ and $v_8$ measured with respect to plane of lower order harmonics are given accordingly.
Klein-Gordon Equation in Hydrodynamical Form
Cheuk-Yin Wong
2010-12-22
We follow and modify the Feshbach-Villars formalism by separating the Klein-Gordon equation into two coupled time-dependent Schroedinger equations for particle and antiparticle wave function components with positive probability densities. We find that the equation of motion for the probability densities is in the form of relativistic hydrodynamics where various forces have their classical counterparts, with the additional element of the quantum stress tensor that depends on the derivatives of the amplitude of the wave function. We derive the equation of motion for the Wigner function and we find that its approximate classical weak-field limit coincides with the equation of motion for the distribution function in the collisionless kinetic theory.
Hydrodynamic models for slurry bubble column reactors
Gidaspow, D. [IIT Center, Chicago, IL (United States)
1995-12-31
The objective of this investigation is to convert a {open_quotes}learning gas-solid-liquid{close_quotes} fluidization model into a predictive design model. This model is capable of predicting local gas, liquid and solids hold-ups and the basic flow regimes: the uniform bubbling, the industrially practical churn-turbulent (bubble coalescence) and the slugging regimes. Current reactor models incorrectly assume that the gas and the particle hold-ups (volume fractions) are uniform in the reactor. They must be given in terms of empirical correlations determined under conditions that radically differ from reactor operation. In the proposed hydrodynamic approach these hold-ups are computed from separate phase momentum balances. Furthermore, the kinetic theory approach computes the high slurry viscosities from collisions of the catalyst particles. Thus particle rheology is not an input into the model.
Fluctuating hydrodynamics of multispecies mixtures. I. Non-reacting Flows Kaushik Balakrishnan,1
Bell, John B.
of hydrodynamic fluctuations is not restricted to mesoscale phenomena. Laboratory experiments involving gases
Characterizing Flow in Oil Reservoir Rock Using Smooth Particle Hydrodynamics
Holmes, David W.
In this paper, a 3D Smooth Particle Hydrodynamics (SPH) simulator for modeling grain scale fluid flow in porous rock is presented. The versatility of the SPH method has driven its use in increasingly complex areas of flow ...
The hydrodynamics of water-walking insects and spiders
Hu, David L., 1979-
2006-01-01
We present a combined experimental and theoretical investigation of the numerous hydrodynamic propulsion mechanisms employed by water-walking arthropods (insects and spiders). In our experimental study, high speed ...
Hydrodynamics and sediment transport in natural and beneficial use marshes
Kushwaha, Vaishali
2006-10-30
or siltation. The research reported here applies an engineering approach to analysis of tidal creeks in natural and beneficial use marshes of Galveston Bay. The hydrodynamic numerical model, DYNLET, was used to assess circulation in marsh channels. A...
Bulk viscosity and cavitation in boost-invariant hydrodynamic expansion
Rajagopal, Krishna
We solve second order relativistic hydrodynamics equations for a boost-invariant 1+1-dimensional expanding fluid with an equation of state taken from lattice calculations of the thermodynamics of strongly coupled quark-gluon ...
Hydrodynamic analysis of the offshore floating nuclear power plant
Strother, Matthew Brian
2015-01-01
Hydrodynamic analysis of two models of the Offshore Floating Nuclear Plant [91 was conducted. The OFNP-300 and the OFNP-1100 were both exposed to computer simulated sea states in the computer program OrcaFlex: first to ...
A GPU Accelerated Smoothed Particle Hydrodynamics Capability For Houdini
Sanford, Mathew
2012-10-19
on the desired result. One common fluid simulation technique is the Smoothed Particle Hydrodynamics (SPH) method. This method is highly parellelizable. I have implemented a method to integrate a Graphics Processor Unit (GPU) accelerated SPH capability into the 3D...
Foundation of Hydrodynamics for Systems with Strong Interactions
Cheuk-Yin Wong
2010-11-30
For a dense and strongly interacting system, such as a nucleus or a strongly-coupled quark-gluon plasma, the foundation of hydrodynamics can be better found in the quantum description of constituents moving in the strong mean fields generated by all other particles. Using the result that the Schroedinger equation and the Klein-Gordon equation can be written in hydrodynamical forms, we find that the probability currents of the many-body system in the mean-field description obey a hydrodynamical equation with stress tensors arising from many contributions: quantum effects, mean-field interactions, and thermal fluctuations. The influence of various contributions to the hydrodynamical motion is expected to vary with the temperature, as the quantum and mean-field stress tensors playing more important roles at low and moderate temperatures.
EIS-0228: Dual Axis Radiographic Hydrodynamic Test (DARHT) Facility
Broader source: Energy.gov [DOE]
This EIS evaluates the potential environmental impact of a proposal to construct and operate the Dual Axis Radiographic Hydrodynamic Test (DARHT) facility at Los Alamos National Laboratory (LANL)...
Triangular flow in hydrodynamics and transport theory
Alver, Burak Han [Laboratory for Nuclear Science, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139-4307 (United States); Gombeaud, Clement; Luzum, Matthew; Ollitrault, Jean-Yves [CNRS, URA2306, IPhT, Institut de physique theorique de Saclay, F-91191 Gif-sur-Yvette (France)
2010-09-15
In ultrarelativistic heavy-ion collisions, the Fourier decomposition of the relative azimuthal angle, {Delta}{phi}, distribution of particle pairs yields a large cos(3{Delta}{phi}) component, extending to large rapidity separations {Delta}{eta}>1. This component captures a significant portion of the ridge and shoulder structures in the {Delta}{phi} distribution, which have been observed after contributions from elliptic flow are subtracted. An average finite triangularity owing to event-by-event fluctuations in the initial matter distribution, followed by collective flow, naturally produces a cos(3{Delta}{phi}) correlation. Using ideal and viscous hydrodynamics and transport theory, we study the physics of triangular (v{sub 3}) flow in comparison to elliptic (v{sub 2}), quadrangular (v{sub 4}), and pentagonal (v{sub 5}) flow. We make quantitative predictions for v{sub 3} at RHIC and LHC as a function of centrality and transverse momentum. Our results for the centrality dependence of v{sub 3} show a quantitative agreement with data extracted from previous correlation measurements by the STAR collaboration. This study supports previous results on the importance of triangular flow in the understanding of ridge and shoulder structures. Triangular flow is found to be a sensitive probe of initial geometry fluctuations and viscosity.
Hamiltonian Hydrodynamics and Irrotational Binary Inspiral
Charalampos M. Markakis
2014-10-28
Gravitational waves from neutron-star and black-hole binaries carry valuable information on their physical properties and probe physics inaccessible to the laboratory. Although development of black-hole gravitational-wave templates in the past decade has been revolutionary, the corresponding work for double neutron-star systems has lagged. Neutron stars can be well-modelled as simple barotropic fluids during the part of binary inspiral most relevant to gravitational wave astronomy, but the crucial geometric and mathematical consequences of this simplification have remained computationally unexploited. In particular, Carter and Lichnerowicz have described barotropic fluid motion via classical variational principles as conformally geodesic. Moreover, Kelvin's circulation theorem implies that initially irrotational flows remain irrotational. Applied to numerical relativity, these concepts lead to novel Hamiltonian or Hamilton-Jacobi schemes for evolving relativistic fluid flows. Hamiltonian methods can conserve not only flux, but also circulation and symplecticity, and moreover do not require addition of an artificial atmosphere typically required by standard conservative methods. These properties can allow production of high-precision gravitational waveforms at low computational cost. This canonical hydrodynamics approach is applicable to a wide class of problems involving theoretical or computational fluid dynamics.
A new three-dimensional general-relativistic hydrodynamics code
Luca Baiotti; Ian Hawke; Pedro J. Montero; Luciano Rezzolla
2010-04-22
We present a new three-dimensional general relativistic hydrodynamics code, the Whisky code. This code incorporates the expertise developed over the past years in the numerical solution of Einstein equations and of the hydrodynamics equations in a curved spacetime, and is the result of a collaboration of several European Institutes. We here discuss the ability of the code to carry out long-term accurate evolutions of the linear and nonlinear dynamics of isolated relativistic stars.
Screening of hydrodynamic interactions for polyelectrolytes in salt solution
Jens Smiatek; Friederike Schmid
2008-09-30
We provide numerical evidence that hydrodynamic interactions are screened for charged polymers in salt solution on time scales below the Zimm time. At very short times, a crossover to hydrodynamic behavior is observed. Our conclusions are drawn from extensive coarse-grained computer simulations of polyelectrolytes in explicit solvent and explicit salt, and discussed in terms of analytical arguments based on the Debye-Hueckel approximation.
Fluctuating hydrodynamics approach to equilibrium time correlations for anharmonic chains
Herbert Spohn
2015-05-22
Linear fluctuating hydrodynamics is a useful and versatile tool for describing fluids, as well as other systems with conserved fields, on a mesoscopic scale. In one spatial dimension, however, transport is anomalous, which requires to develop a nonlinear extension of fluctuating hydrodynamics. The relevant nonlinearity turns out to be the quadratic part of the Euler currents when expanding relative to a uniform background. We outline the theory and compare with recent molecular dynamics simulations.
Sedimentation of pairs of hydrodynamically interacting semiflexible filaments
Isaac Llopis; Ignacio Pagonabarraga; Marco Cosentino Lagomarsino; Christopher P. Lowe
2007-10-08
We describe the effect of hydrodynamic interactions in the sedimentation of a pair of inextensible semiflexible filaments under a uniform constant force at low Reynolds numbers. We have analyzed the different regimes and the morphology of such polymers in simple geometries, which allow us to highlight the peculiarities of the interplay between elastic and hydrodynamic stresses. Cooperative and symmetry breaking effects associated to the geometry of the fibers gives rise to characteristic motion which give them distinct properties from rigid and elastic filaments.
Annual Report 2006 for Hydrodynamics and Radiation Hydrodynamics with Astrophysical Applications
R. Paul Drake
2007-04-05
We report the ongoing work of our group in hydrodynamics and radiation hydrodynamics with astrophysical applications. During the period of the existing grant, we have carried out two types of experiments at the Omega laser. One set of experiments has studied radiatively collapsing shocks, obtaining data using a backlit pinhole with a 100 ps backlighter and beginning to develop the ability to look into the shock tube with optical or x-ray diagnostics. Other experiments have studied the deeply nonlinear development of the Rayleigh-Taylor (RT) instability from complex initial conditions, using dual-axis radiographic data with backlit pinholes and ungated detectors to complete the data set for a Ph.D. student. We lead a team that is developing a proposal for experiments at the National Ignition Facility and are involved in experiments at NIKE and LIL. All these experiments have applications to astrophysics, discussed in the corresponding papers. We assemble the targets for the experiments at Michigan, where we also prepare many of the simple components. We also have several projects underway in our laboratory involving our x-ray source. The above activities, in addition to a variety of data analysis and design projects, provide good experience for graduate and undergraduates students. In the process of doing this research we have built a research group that uses such work to train junior scientists.
Early hydrodynamic evolution of a stellar collision
Kushnir, Doron; Katz, Boaz [Institute for Advanced Study, Einstein Drive, Princeton, NJ 08540 (United States)
2014-04-20
The early phase of the hydrodynamic evolution following the collision of two stars is analyzed. Two strong shocks propagate from the contact surface and move toward the center of each star at a velocity that is a small fraction of the velocity of the approaching stars. The shocked region near the contact surface has a planar symmetry and a uniform pressure. The density vanishes at the (Lagrangian) surface of contact, and the speed of sound diverges there. The temperature, however, reaches a finite value, since as the density vanishes, the finite pressure is radiation dominated. For carbon-oxygen white dwarf (CO WD) collisions, this temperature is too low for any appreciable nuclear burning shortly after the collision, which allows for a significant fraction of the mass to be highly compressed to the density required for efficient {sup 56}Ni production in the detonation wave that follows. This property is crucial for the viability of collisions of typical CO WD as progenitors of type Ia supernovae, since otherwise only massive (>0.9 M {sub ?}) CO WDs would have led to such explosions (as required by all other progenitor models). The divergence of the speed of sound limits numerical studies of stellar collisions, as it makes convergence tests exceedingly expensive unless dedicated schemes are used. We provide a new one-dimensional Lagrangian numerical scheme to achieve this. A self-similar planar solution is derived for zero-impact parameter collisions between two identical stars, under some simplifying assumptions (including a power-law density profile), which is the planar version of previous piston problems that were studied in cylindrical and spherical symmetries.
Hydrodynamic construction of the electromagnetic field
Peter Holland
2014-10-03
We present an alternative Eulerian hydrodynamic model for the electromagnetic field in which the discrete vector indices in Maxwell\\s equations are replaced by continuous angular freedoms, and develop the corresponding Lagrangian picture in which the fluid particles have rotational and translational freedoms. This enables us to extend to the electromagnetic field the exact method of state construction proposed previously for spin 0 systems, in which the time-dependent wavefunction is computed from a single-valued continuum of deterministic trajectories where two spacetime points are linked by at most a single orbit. The deduction of Maxwell\\s equations from continuum mechanics is achieved by generalizing the spin 0 theory to a general Riemannian manifold from which the electromagnetic construction is extracted as a special case. In particular, the flat-space Maxwell equations are represented as a curved-space Schr\\"odinger equation for a massive system. The Lorentz covariance of the Eulerian field theory is obtained from the non-covariant Lagrangian-coordinate model as a kind of collective effect. The method makes manifest the electromagnetic analogue of the quantum potential that is tacit in Maxwell\\s equations. This implies a novel definition of the \\classical limit\\ of Maxwell\\s equations that differs from geometrical optics. It is shown that Maxwell\\s equations may be obtained by canonical quantization of the classical model. Using the classical trajectories a novel expression is derived for the propagator of the electromagnetic field in the Eulerian picture. The trajectory and propagator methods of solution are illustrated for the case of a light wave.
Understanding the Hydrodynamics of Swimming: From Fish Fins to Flexible Propulsors for Autonomous
Lauder, George V.
Understanding the Hydrodynamics of Swimming: From Fish Fins to Flexible Propulsors for Autonomous Corporation, Burlington, MA, USA 2 Department of Mechanical Engineering, Drexel University, Philadelphia, PA, USA 3 Museum of Comparative Zoology, Harvard University, Cambridge, MA, USA 4 Department of Mechanical
Extreme hydrodynamic atmospheric loss near the critical thermal escape regime
Erkaev, N V; Odert, P; Kulikov, Yu N; Kislyakova, K G
2015-01-01
By considering martian-like planetary embryos inside the habitable zone of solar-like stars we study the behavior of the hydrodynamic atmospheric escape of hydrogen for small values of the Jeans escape parameter $\\beta thermal energy. Our study is based on a 1-D hydrodynamic upper atmosphere model that calculates the volume heating rate in a hydrogen dominated thermosphere due to the absorption of the stellar soft X-ray and extreme ultraviolet (XUV) flux. We find that when the $\\beta$ value near the mesopause/homopause level exceeds a critical value of $\\sim$2.5, there exists a steady hydrodynamic solution with a smooth transition from subsonic to supersonic flow. For a fixed XUV flux, the escape rate of the upper atmosphere is an increasing function of the temperature at the lower boundary. Our model results indicate a crucial enhancement of the atmospheric escape rate, when the Jeans escape parameter $\\beta$ decr...
Hydrodynamic Correlations slow down Crystallization of Soft Colloids
Roehm, Dominic; Arnold, Axel
2013-01-01
Crystallization is often assumed to be a quasi-static process that is unaffected by details of particle transport other than the bulk diffusion coefficient. Therefore colloidal suspensions are frequently argued to be an ideal toy model for experimentally more difficult systems such as metal melts. In this letter, we want to challenge this assumption. To this aim, we have considered molecular dynamics simulations of the crystallization in a suspension of Yukawa-type colloids. In order to investigate the role of hydrodynamic interactions (HIs) mediated by the solvent, we modeled the solvent both implicitly and explicitly, using Langevin dynamics and the fluctuating Lattice Boltzmann method, respectively. Our simulations show a dramatic reduction of the crystal growth velocity due to HIs even at moderate hydrodynamic coupling. A detailed analysis shows that this slowdown is due to the wall-like properties of the crystal surface, which reduces the colloidal diffusion towards the crystal surface by hydrodynamic sc...
Anisotropic hydrodynamics for mixture of quark and gluon fluids
Florkowski, Wojciech; Ryblewski, Radoslaw; Tinti, Leonardo
2015-01-01
A system of equations for anisotropic hydrodynamics is derived that describes a mixture of anisotropic quark and gluon fluids. The consistent treatment of the zeroth, first and second moments of the kinetic equations allows us to construct a new framework with more general forms of the anisotropic phase-space distribution functions than those used before. In this way, the main difficiencies of the previous formulations of anisotropic hydrodynamics for mixtures have been overcome and the good agreement with the exact kinetic-theory results is obtained.
Hydrodynamic evolution and jet energy loss in Cu + Cu collisions
Schenke, Bjoern; Jeon, Sangyong; Gale, Charles
2011-04-15
We present results from a hybrid description of Cu + Cu collisions using (3 + 1)-dimensional hydrodynamics (music) for the bulk evolution and a Monte Carlo simulation (martini) for the evolution of high-momentum partons in the hydrodynamical background. We explore the limits of this description by going to small system sizes and determine the dependence on different fractions of wounded nucleon and binary collisions scaling of the initial energy density. We find that Cu + Cu collisions are well described by the hybrid description at least up to 20% central collisions.
Accounting for backflow in hydrodynamic-simulation interfaces
Scott Pratt
2014-01-01
Methods for building a consistent interface between hydrodynamic and simulation modules is presented. These methods account for the backflow across the hydrodynamic/simulation hyper-surface. The algorithms are efficient, relatively straight-forward to implement, and account for conservation laws across the hyper-surface. The methods also account for the spurious interactions between particles in the backflow and other particles by following the subsequent impact of such particles. Since the number of altered trajectories grows exponentially in time, a cutoff is built into the procedure so that the effects of the backflow are ignored beyond a certain number of collisions
3-D HYDRODYNAMIC MODELING IN A GEOSPATIAL FRAMEWORK
Bollinger, J; Alfred Garrett, A; Larry Koffman, L; David Hayes, D
2006-08-24
3-D hydrodynamic models are used by the Savannah River National Laboratory (SRNL) to simulate the transport of thermal and radionuclide discharges in coastal estuary systems. Development of such models requires accurate bathymetry, coastline, and boundary condition data in conjunction with the ability to rapidly discretize model domains and interpolate the required geospatial data onto the domain. To facilitate rapid and accurate hydrodynamic model development, SRNL has developed a pre- and post-processor application in a geospatial framework to automate the creation of models using existing data. This automated capability allows development of very detailed models to maximize exploitation of available surface water radionuclide sample data and thermal imagery.
Benedict, Joshua King
2011-01-01
For the hydrodynamic feature analyzed full cavitation wassignificant cavitation affects as well as hydrodynamic loadcavitation is maintained across the area of this particular macro/micro-feature, an increase in hydrodynamic
Martone, Patrick T.
VARIATION IN ANATOMICAL AND MATERIAL PROPERTIES EXPLAINS DIFFERENCES IN HYDRODYNAMIC PERFORMANCES that material properties of seaweed tissues may influence their fitness. Because hydrodynamic forces are likely difficult to disentangle the effects of materials properties on seaweed performance because size, shape
Palanker, Daniel
Multifocal laser surgery: Cutting enhancement by hydrodynamic interactions between cavitation a single cavitation bubble. We investigate the hydrodynamic interactions between simultaneous cavitation bubbles originating from multiple laser foci. Simultaneous expansion and collapse of cavitation bubbles
Self-Similar Radiation-Hydrodynamics Solutions in the Equilibrium Diffusion Limit
Lane, Taylor Kinsey
2013-01-31
, radiation, and shock waves. These phenomena can be found in supernovae explosions, or in inertial confinement fusion applications. Hydrodynamics Model To begin to understand the complex flows involved with RHD, it is important to first consider hydrodynamics...
Epps, Brenden P
2010-01-01
This thesis presents an impulse framework for analyzing the hydrodynamic forces on bodies in flow. This general theoretical framework is widely applicable, and it is used to address the hydrodynamics of fish propulsion, ...
Event-by-event hydrodynamics: A better tool to study the Quark-Gluon plasma
Grassi, Frederique
2013-03-25
Hydrodynamics has been established as a good tool to describe many data from relativistic heavyion collisions performed at RHIC and LHC. More recently, it has become clear that it is necessary to use event-by-event hydrodynamics (i.e. describe each collision individually using hydrodynamics), an approach first developed in Brazil. In this paper, I review which data require the use of event-by-event hydrodynamics and what more we may learn on the Quark-Gluon Plasma with this.
CHARACTERIZATION OF SURFACE ROUGHNESS AND INITIAL CONDITIONS FOR CYLINDRICAL HYDRODYNAMIC
Barnes, Cris W.
CHARACTERIZATION OF SURFACE ROUGHNESS AND INITIAL CONDITIONS FOR CYLINDRICAL HYDRODYNAMIC AND MIX across a variable density interface, that interface must be well characterized. There exist a number, characterizing, and affecting the surface roughness was driven by Ablative Rayleigh-Taylor work5
Quasi-two Dimensional Hydrodynamics and Interaction of Vortex Tubes
Zakharov, Vladimir
Quasi-two Dimensional Hydrodynamics and Interaction of Vortex Tubes Vladimir Zakharov 1 but a careful study of the dynamics of the vortex tubes or their systems in a real 3-dimentional nonstationary for description of this type of flow looks very timely. Another motivation is the vortex dynamics
A hydrodynamic theory for solutions of nonhomogeneous nematic liquid crystalline
A hydrodynamic theory for solutions of nonhomogeneous nematic liquid crystalline polymers liquid crystalline polymers (LCPs) of spheroidal molecular con#12;gurations is ex- tended to account molar weight liquid crystalline polymers. Although the LE theory was #12;rst developed for rodlike
Generalised hydrodynamic reductions of the kinetic equation for soliton gas
Generalised hydrodynamic reductions of the kinetic equation for soliton gas Gennady A. El1 , Maxim of Russian Academy of Sciences, Moscow, 53 Leninskij Prospekt, Moscow, Russia 3 Laboratory of Geometric, Moscow, Russia 4 Institute for Nuclear Research, National Academy of Sciences of Ukraine, 47 pr. Nauky
Solvent structure and hydrodynamic effects in photoinduced electron transfer
Fayer, Michael D.
Solvent structure and hydrodynamic effects in photoinduced electron transfer S. F. Swallen, Kristin to account for realistic finite-volume solvent effects. This work introduces physically important effects caused by the solvent which fundamentally affect the rates and spatial distribution of charge transfer
Hydrodynamics and Fluctuations Outside of Local Equilibrium: Driven Diffusive Systems
ago by Price between the covariance matrix of electrical current noise and the bulk diffusion matrix¨unchen, Germany 1 #12; Abstract We derive hydrodynamic equations for systems not in local thermodynamic systems(DDS), such as electrical conductors in an applied field with diffusion of charge carriers
Smoothed Particle Hydrodynamics and Magnetohydrodynamics Daniel J. Price
Price, Daniel
Smoothed Particle Hydrodynamics and Magnetohydrodynamics Daniel J. Price Centre for Stellar reviews already exist (e.g. Monaghan, 1992, 2005; Price, 2004; Rosswog, 2009), there remain particularly of the otherwise unpublished material in my PhD thesis (Price, 2004). Email address: daniel.price
Linearly resummed hydrodynamics in a weakly curved spacetime
Yanyan Bu; Michael Lublinsky
2015-02-27
We extend our study of all-order linearly resummed hydrodynamics in a flat space~\\cite{1406.7222,1409.3095} to fluids in weakly curved spaces. The underlying microscopic theory is a finite temperature $\\mathcal{N}=4$ super-Yang-Mills theory at strong coupling. The AdS/CFT correspondence relates black brane solutions of the Einstein gravity in asymptotically \\emph{locally} $\\textrm{AdS}_5$ geometry to relativistic conformal fluids in a weakly curved 4D background. To linear order in the amplitude of hydrodynamic variables and metric perturbations, the fluid's energy-momentum tensor is computed with derivatives of both the fluid velocity and background metric resummed to all orders. We extensively discuss the meaning of all order hydrodynamics by expressing it in terms of the memory function formalism, which is also suitable for practical simulations. In addition to two viscosity functions discussed at length in refs.~\\cite{1406.7222,1409.3095}, we find four curvature induced structures coupled to the fluid via new transport coefficient functions. In ref.~\\cite{0905.4069}, the latter were referred to as gravitational susceptibilities of the fluid. We analytically compute these coefficients in the hydrodynamic limit, and then numerically up to large values of momenta.
Sedimentation, Pclet number, and hydrodynamic screening Kiley Benes,1
Tong, Penger
Sedimentation, Péclet number, and hydrodynamic screening Kiley Benes,1 Penger Tong,2 and Bruce J January 2007; revised manuscript received 7 May 2007; published 8 November 2007 The sedimentation of hard. Two functional forms for the sedimentation velocity as a function of particle concen- tration
Oliinychenko, Dmytro
2015-01-01
Many hybrid models of heavy ion collisions construct the initial state for hydrodynamics from transport models. Hydrodynamics requires that the energy-momentum tensor $T^{\\mu\
Dmytro Oliinychenko; Hannah Petersen
2015-08-18
Many hybrid models of heavy ion collisions construct the initial state for hydrodynamics from transport models. Hydrodynamics requires that the energy-momentum tensor $T^{\\mu\
Chemistry Induced by Hydrodynamic Cavitation Kenneth S. Suslick,* Millan M. Mdleleni, and
Suslick, Kenneth S.
Chemistry Induced by Hydrodynamic Cavitation Kenneth S. Suslick,* Millan M. Mdleleni, and Jeffrey T investigated during recent years,1-5 little is known about the chemical consequences of hydrodynamic cavitation resulted from hydrodynamic cavitation within the fluidizer.11 We describe here conclusive experimental
Pulsed power hydrodynamics : a new application of high magnetic fields.
Reinovsky, R. E. (Robert E.); Anderson, W. E. (Wallace E.); Atchison, W. L. (Walter L.); Faehl, R. J. (Rickey J.); Keinigs, R. K. (Rhonald K.); Lindemuth, I. R.; Scudder, D. W. (David W.); Shlachter, Jack S.; Taylor, Antoinette J.,
2002-01-01
Pulsed Power Hydrodynamics is a new application of high magnetic fields recently developed to explore advanced hydrodynamics, instabilities, fluid turbulences, and material properties in a highly precise, controllable environment at the extremes of pressure and material velocity. The Atlas facility at Los Alamos is the world's first and only laboratory pulsed power system designed specifically to explore this relatively new family of megagauss magnetic field applications. Constructed in 2000 and commissioned in August 2001, Atlas is a 24-MJ high-performance capacitor bank delivering up to 30 MA with a current risetime of 5-6 {micro}sec. The high-precision, cylindrical, imploding liner is the tool most frequently used to convert electrical energy into the hydrodynamic (particle kinetic) energy needed to drive the experiments. For typical liner parameters including initial radius of 5 cm, the peak current of 30 MA delivered by Atlas results in magnetic fields just over 1 MG outside the liner prior to implosion. During the 5 to 10-{micro}sec implosion, the field outside the liner rises to several MG in typical situations. At these fields the rear surface of the liner is melted and it is subject to a variety of complex behaviors including: diffusion dominated andor melt wave field penetration and heating, magneto Raleigh-Taylor sausage mode behavior at the liner/field interface, and azimuthal asymmetry due to perturbations in current drive. The first Atlas liner implosion experiments were conducted in September 2000 and 10-15 experiments are planned in the: first year of operation. Immediate applications of the new pulsed power hydrodynamics techniques include material property topics including: exploration of material strength at high rates of strain, material failure including fracture and spall, and interfacial dynamics at high relative velocities and high interfacial pressures. A variety of complex hydrodynamic geometries will be explored and experiments will be designed to explore uristable perturbation growth and transition to turbulence. This paper will provide an overview of the range of problems to which pulsed power hydrodynamics can be applied and the issues associated with these techniques. Other papers at this Conference will present specifics of individual experiments and elaborate on the liner physics issues.
Numeric spectral radiation hydrodynamic calculations of supernova shock breakouts
Sapir, Nir; Halbertal, Dorri [Department of Particle Physics and Astrophysics, Weizmann Institute of Science, Rehovot 76100 (Israel)
2014-12-01
We present here an efficient numerical scheme for solving the non-relativistic one-dimensional radiation-hydrodynamics equations including inelastic Compton scattering, which is not included in most codes and is crucial for solving problems such as shock breakout. The devised code is applied to the problems of a steady-state planar radiation mediated shock (RMS) and RMS breakout from a stellar envelope. The results are in agreement with those of a previous work on shock breakout, in which Compton equilibrium between matter and radiation was assumed and the 'effective photon' approximation was used to describe the radiation spectrum. In particular, we show that the luminosity and its temporal dependence, the peak temperature at breakout, and the universal shape of the spectral fluence derived in this earlier work are all accurate. Although there is a discrepancy between the spectral calculations and the effective photon approximation due to the inaccuracy of the effective photon approximation estimate of the effective photon production rate, which grows with lower densities and higher velocities, the difference in peak temperature reaches only 30% for the most discrepant cases of fast shocks in blue supergiants. The presented model is exemplified by calculations for supernova 1987A, showing the detailed evolution of the burst spectrum. The incompatibility of the stellar envelope shock breakout model results with observed properties of X-ray flashes (XRFs) and the discrepancy between the predicted and observed rates of XRFs remain unexplained.
Radiation Hydrodynamical Evolution of Primordial H II Regions
Daniel Whalen; Tom Abel; Michael L. Norman
2004-03-02
We simulate the ionization environment of z ~ 20 luminous objects formed within the framework of the current CDM cosmology and compute their UV escape fraction. These objects are likely single very massive stars that are copious UV emitters. We present analytical estimates as well as one--dimensional radiation hydrodynamical calculations of the evolution of these first HII regions in the universe. The initially D--type ionization front evolves to become R--type within $\\lesssim 10^5$ yrs at a distance $\\sim1$ pc. This ionization front then completely overruns the halo, accelerating an expanding shell of gas outward to velocities in excess of 30 km s$^{-1}$, about ten times the escape velocity of the confining dark matter halo. We find that the evolution of the HII region depends only weakly on the assumed stellar ionizing luminosities. Consequently, most of the gas surrounding the first stars will leave the dark halo whether or not the stars produce supernovae. If they form the first massive seed black holes these are unlikely to accrete within a Hubble time after they formed until they are incorporated into larger dark matter halos that contain more gas. Because these I--fronts exit the halo on timescales much shorter than the stars' main sequence lifetimes their host halos have UV escape fractions of $\\gtrsim 0.95$, fixing an important parameter for theoretical studies of cosmological hydrogen reionization.
Soft Photons from transport and hydrodynamics at FAIR energies
Andreas Grimm; Bjørn Bäuchle
2012-11-11
Direct photon spectra from uranium-uranium collisions at FAIR energies (E(lab) = 35 AGeV) are calculated within the hadronic Ultra-relativistic Quantum Molecular Dynamics transport model. In this microscopic model, one can optionally include a macroscopic intermediate hydrodynamic phase. The hot and dense stage of the collision is then modeled by a hydrodynamical calculation. Photon emission from transport-hydro hybrid calculations is examined for purely hadronic matter and matter that has a cross-over phase transition and a critical end point to deconfined and chirally restored matter at high temperatures. We find the photon spectra in both scenarios to be dominated by Bremsstrahlung. Comparing flow of photons in both cases suggests a way to distinguish these two scenarios.
A hydrodynamic approach to non-equilibrium conformal field theories
Denis Bernard; Benjamin Doyon
2015-07-27
We develop a hydrodynamic approach to non-equilibrium conformal field theory. We study non-equilibrium steady states in the context of one-dimensional conformal field theory perturbed by the $T\\bar T$ irrelevant operator. By direct quantum computation, we show, to first order in the coupling, that a relativistic hydrodynamic emerges, which is a simple modification of one-dimensional conformal fluids. We show that it describes the steady state and its approach, and we provide the main characteristics of the steady state, which lies between two shock waves. The velocities of these shocks are modified by the perturbation and equal the sound velocities of the asymptotic baths. Pushing further this approach, we are led to conjecture that the approach to the steady state is generically controlled by the power law $t^{-1/2}$, and that the widths of the shocks increase with time according to $t^{1/3}$.
A hydrodynamic approach to non-equilibrium conformal field theories
Bernard, Denis
2015-01-01
We develop a hydrodynamic approach to non-equilibrium conformal field theory. We study non-equilibrium steady states in the context of one-dimensional conformal field theory perturbed by the $T\\bar T$ irrelevant operator. By direct quantum computation, we show, to first order in the coupling, that a relativistic hydrodynamic emerges, which is a simple modification of one-dimensional conformal fluids. We show that it describes the steady state and its approach, and we provide the main characteristics of the steady state, which lies between two shock waves. The velocities of these shocks are modified by the perturbation and equal the sound velocities of the asymptotic baths. Pushing further this approach, we are led to conjecture that the approach to the steady state is generically controlled by the power law $t^{-1/2}$, and that the widths of the shocks increase with time according to $t^{1/3}$.
A hydrodynamic approach to boost invariant free streaming
Esteban Calzetta
2015-08-10
We consider a family of exact boost invariant solutions of the transport equation for free streaming massless particles, where the one particle distribution function is defi?ned in terms of a function of a single variable. The evolution of second and third moments of the one particle distribution function (the second moment being the energy momentum tensor (EMT) and the third moment the non equilibrium current (NEC)) depends only on two moments of that function. Given those two moments we show how to build a non linear hydrodynamic theory which reproduces the early time evolution of the EMT and the NEC. The structure of these theories may give insight on nonlinear hydrodynamic phenomena on short time scales.
Hydrodynamics of an inelastic gas with implications for sonochemistry
James F. Lutsko
2005-10-09
The hydrodynamics for a gas of hard-spheres which sometimes experience inelastic collisions resulting in the loss of a fixed, velocity-independent, amount of energy $\\Delta $ is investigated with the goal of understanding the coupling between hydrodynamics and endothermic chemistry. The homogeneous cooling state of a uniform system and the modified Navier-Stokes equations are discussed and explicit expressions given for the pressure, cooling rates and all transport coefficients for D-dimensions. The Navier-Stokes equations are solved numerically for the case of a two-dimensional gas subject to a circular piston so as to illustrate the effects of the enegy loss on the structure of shocks found in cavitating bubbles. It is found that the maximal temperature achieved is a sensitive function of $\\Delta $ with a minimum occuring near the physically important value of $\\Delta \\sim 12,000K \\sim 1eV$
Development and Implementation of Radiation-Hydrodynamics Verification Test Problems
Marcath, Matthew J. [Los Alamos National Laboratory; Wang, Matthew Y. [Los Alamos National Laboratory; Ramsey, Scott D. [Los Alamos National Laboratory
2012-08-22
Analytic solutions to the radiation-hydrodynamic equations are useful for verifying any large-scale numerical simulation software that solves the same set of equations. The one-dimensional, spherically symmetric Coggeshall No.9 and No.11 analytic solutions, cell-averaged over a uniform-grid have been developed to analyze the corresponding solutions from the Los Alamos National Laboratory Eulerian Applications Project radiation-hydrodynamics code xRAGE. These Coggeshall solutions have been shown to be independent of heat conduction, providing a unique opportunity for comparison with xRAGE solutions with and without the heat conduction module. Solution convergence was analyzed based on radial step size. Since no shocks are involved in either problem and the solutions are smooth, second-order convergence was expected for both cases. The global L1 errors were used to estimate the convergence rates with and without the heat conduction module implemented.
Low torque hydrodynamic lip geometry for rotary seals
Dietle, Lannie L.; Schroeder, John E.
2015-07-21
A hydrodynamically lubricating geometry for the generally circular dynamic sealing lip of rotary seals that are employed to partition a lubricant from an environment. The dynamic sealing lip is provided for establishing compressed sealing engagement with a relatively rotatable surface, and for wedging a film of lubricating fluid into the interface between the dynamic sealing lip and the relatively rotatable surface in response to relative rotation that may occur in the clockwise or the counter-clockwise direction. A wave form incorporating an elongated dimple provides the gradual convergence, efficient impingement angle, and gradual interfacial contact pressure rise that are conducive to efficient hydrodynamic wedging. Skewed elevated contact pressure zones produced by compression edge effects provide for controlled lubricant movement within the dynamic sealing interface between the seal and the relatively rotatable surface, producing enhanced lubrication and low running torque.
Hydrodynamic model of Fukushima-Daiichi NPP Industrial site flooding
Vaschenko, V N; Gerasimenko, T V; Vachev, B
2014-01-01
While the Fukushima-Daiichi was designed and constructed the maximal tsunami height estimate was about 3 m based on analysis of statistical data including Chile earthquake in 1960. The NPP project industrial site height was 10 m. The further deterministic estimates TPCO-JSCE confirmed the impossibility of the industrial site flooding by a tsunami and therefore confirmed ecological safety of the NPP. However, as a result of beyond design earthquake of 11 March 2011 the tsunami height at the shore near the Fukushima-Daiichi NPP reached 15 m. This led to flooding and severe emergencies having catastrophic environmental consequences. This paper proposes hydrodynamic model of tsunami emerging and traveling based on conservative assumptions. The possibility of a tsunami wave reaching 15 m height at the Fukushima-Daiichi NPP shore was confirmed for deduced hydrodynamic resistance coefficient of 1.8. According to the model developed a possibility of flooding is determined not only by the industrial site height, magni...
Galaxies that Shine: radiation-hydrodynamical simulations of disk galaxies
Rosdahl, Joakim; Teyssier, Romain; Agertz, Oscar
2015-01-01
Radiation feedback is typically implemented using subgrid recipes in hydrodynamical simulations of galaxies. Very little work has so far been performed using radiation-hydrodynamics (RHD), and there is no consensus on the importance of radiation feedback in galaxy evolution. We present RHD simulations of isolated galaxy disks of different masses with a resolution of 18 pc. Besides accounting for supernova feedback, our simulations are the first galaxy-scale simulations to include RHD treatments of photo-ionisation heating and radiation pressure, from both direct optical/UV radiation and multi-scattered, re-processed infrared (IR) radiation. Photo-heating smooths and thickens the disks and suppresses star formation about as much as the inclusion of ("thermal dump") supernova feedback does. These effects decrease with galaxy mass and are mainly due to the prevention of the formation of dense clouds, as opposed to their destruction. Radiation pressure, whether from direct or IR radiation, has little effect, but ...
Hydrodynamic instabilities in beryllium targets for the National Ignition Facility
Yi, S. A., E-mail: austinyi@lanl.gov; Simakov, A. N.; Wilson, D. C.; Olson, R. E.; Kline, J. L.; Batha, S. H. [Los Alamos National Laboratory, P.O. Box 1663, Los Alamos, New Mexico 87545 (United States); Clark, D. S.; Hammel, B. A.; Milovich, J. L.; Salmonson, J. D.; Kozioziemski, B. J. [Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, California 94551 (United States)
2014-09-15
Beryllium ablators offer higher ablation velocity, rate, and pressure than their carbon-based counterparts, with the potential to increase the probability of achieving ignition at the National Ignition Facility (NIF) [E. I. Moses et al., Phys. Plasmas 16, 041006 (2009)]. We present here a detailed hydrodynamic stability analysis of low (NIF Revision 6.1) and high adiabat NIF beryllium target designs. Our targets are optimized to fully utilize the advantages of beryllium in order to suppress the growth of hydrodynamic instabilities. This results in an implosion that resists breakup of the capsule, and simultaneously minimizes the amount of ablator material mixed into the fuel. We quantify the improvement in stability of beryllium targets relative to plastic ones, and show that a low adiabat beryllium capsule can be at least as stable at the ablation front as a high adiabat plastic target.
A new hydrodynamics code for Type Ia Supernovae
Leung, S -C; Lin, L -M
2015-01-01
A two-dimensional hydrodynamics code for Type Ia supernovae (SNIa) simulations is presented. The code includes a fifth-order shock-capturing scheme WENO, detailed nuclear reaction network, flame-capturing scheme and sub-grid turbulence. For post-processing we have developed a tracer particle scheme to record the thermodynamical history of the fluid elements. We also present a one-dimensional radiative transfer code for computing observational signals. The code solves the Lagrangian hydrodynamics and moment-integrated radiative transfer equations. A local ionization scheme and composition dependent opacity are included. Various verification tests are presented, including standard benchmark tests in one and two dimensions. SNIa models using the pure turbulent deflagration model and the delayed-detonation transition model are studied. The results are consistent with those in the literature. We compute the detailed chemical evolution using the tracer particles' histories, and we construct corresponding bolometric...
THE KOZAI-LIDOV MECHANISM IN HYDRODYNAMICAL DISKS
Martin, Rebecca G.; Nixon, Chris; Armitage, Philip J. [JILA, University of Colorado and NIST, UCB 440, Boulder, CO 80309 (United States); Lubow, Stephen H. [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States); Price, Daniel J. [Monash Centre for Astrophysics (MoCA), School of Mathematical Sciences, Monash University, Clayton, Vic. 3800 (Australia); Do?an, Suzan [Department of Astronomy and Space Sciences, University of Ege, Bornova, 35100 ?zmir (Turkey); King, Andrew [Department of Physics and Astronomy, University of Leicester, University Road, Leicester LE1 7RH (United Kingdom)
2014-09-10
We use three-dimensional hydrodynamical simulations to show that a highly misaligned accretion disk around one component of a binary system can exhibit global Kozai-Lidov cycles, where the inclination and eccentricity of the disk are interchanged periodically. This has important implications for accreting systems on all scales, for example, the formation of planets and satellites in circumstellar and circumplanetary disks, outbursts in X-ray binary systems, and accretion onto supermassive black holes.
Skew and twist resistant hydrodynamic rotary shaft seal
Dietle, Lannie (Sugar Land, TX); Kalsi, Manmohan Singh (Houston, TX)
1999-01-01
A hydrodynamically lubricated squeeze packing type rotary shaft seal suitable for lubricant retention and environmental exclusion which incorporates one or more resilient protuberances which and cooperate with the gland walls to hold the seal straight in its installation groove in unpressurized and low pressure lubricant retention applications thereby preventing skew-induced wear caused by impingement of abrasive contaminants present in the environment, and which also serve as radial bearings to prevent tipping of the seal within its installation gland.
Skew and twist resistant hydrodynamic rotary shaft seal
Dietle, L.; Kalsi, M.S.
1999-02-23
A hydrodynamically lubricated squeeze packing type rotary shaft seal suitable for lubricant retention and environmental exclusion which incorporates one or more resilient protuberances which cooperate with the gland walls to hold the seal straight in its installation groove in unpressurized and low pressure lubricant retention applications thereby preventing skew-induced wear caused by impingement of abrasive contaminants present in the environment, and which also serve as radial bearings to prevent tipping of the seal within its installation gland. 14 figs.
Hydrodynamic equations for an electron gas in graphene
Luigi Barletti
2015-09-16
In this paper we review, and extend to the non-isothermal case, the results published in [L. Barletti, J. Math. Phys. 55, 083303 (2014)], concerning the application of the maximum entropy closure technique to the derivation of hydrodynamic equations for particles with spin-orbit interaction and Fermi-Dirac statistics. In the second part of the paper we treat in more details the case of electrons on a graphene sheet and investigate various asymptotic regimes
Hydrodynamically Lubricated Rotary Shaft Having Twist Resistant Geometry
Dietle, Lannie (Houston, TX); Gobeli, Jeffrey D. (Houston, TX)
1993-07-27
A hydrodynamically lubricated squeeze packing type rotary shaft with a cross-sectional geometry suitable for pressurized lubricant retention is provided which, in the preferred embodiment, incorporates a protuberant static sealing interface that, compared to prior art, dramatically improves the exclusionary action of the dynamic sealing interface in low pressure and unpressurized applications by achieving symmetrical deformation of the seal at the static and dynamic sealing interfaces. In abrasive environments, the improved exclusionary action results in a dramatic reduction of seal and shaft wear, compared to prior art, and provides a significant increase in seal life. The invention also increases seal life by making higher levels of initial compression possible, compared to prior art, without compromising hydrodynamic lubrication; this added compression makes the seal more tolerant of compression set, abrasive wear, mechanical misalignment, dynamic runout, and manufacturing tolerances, and also makes hydrodynamic seals with smaller cross-sections more practical. In alternate embodiments, the benefits enumerated above are achieved by cooperative configurations of the seal and the gland which achieve symmetrical deformation of the seal at the static and dynamic sealing interfaces. The seal may also be configured such that predetermined radial compression deforms it to a desired operative configuration, even through symmetrical deformation is lacking.
Constructing higher-order hydrodynamics: The third order
Sašo Grozdanov; Nikolaos Kaplis
2015-07-19
Hydrodynamics can be formulated as the gradient expansion of conserved currents in terms of the fundamental fields describing the near-equilibrium fluid flow. In the relativistic case, the Navier-Stokes equations follow from the conservation of the stress-energy tensor to first order in derivatives. In this paper, we go beyond the presently understood second-order hydrodynamics and discuss the systematisation of obtaining the hydrodynamic expansion to an arbitrarily high order. As an example of the algorithm that we present, we fully classify the gradient expansion at third order for neutral fluids in four dimensions, thus finding the most general next-to-leading-order corrections to the relativistic Navier-Stokes equations in curved space-time. In the process, we list $20$ new transport coefficients in the conformal and $68$ in the non-conformal case, without considering any constraints that could potentially arise from the entropy current analysis. We also obtain the third-order corrections to the linear dispersion relations that describe the propagation of diffusion and sound waves in relativistic fluids. We apply our results to the energy-momentum transport in the $\\mathcal{N}=4$ supersymmetric Yang-Mills fluid at infinite 't Hooft coupling and infinite number of colours, to find the values of two new conformal transport coefficients.
Constructing higher-order hydrodynamics: The third order
Grozdanov, Sašo
2015-01-01
Hydrodynamics can be formulated as the gradient expansion of conserved currents, in terms of the fundamental fields describing the near-equilibrium fluid flow. In the relativistic case, the Navier-Stokes equations follow from the conservation of the stress-energy tensor to first order in derivatives. In this paper, we go beyond the presently understood second-order hydrodynamics and discuss the systematisation of obtaining the hydrodynamic expansion to an arbitrarily high order. As an example, we fully classify the gradient expansion at third order for neutral fluids in four dimensions, thus finding the most general next-to-leading-order corrections to the relativistic Navier-Stokes equations. In the process, we list $20$ new transport coefficients in the conformal and $68$ in the non-conformal case. We also obtain the third-order corrections to the linear dispersion relations that describe the propagation of diffusion and sound waves in relativistic fluids. We apply our results to the energy-momentum transpo...
RAM: a Relativistic Adaptive Mesh Refinement Hydrodynamics Code
Zhang, Wei-Qun; MacFadyen, Andrew I.; /Princeton, Inst. Advanced Study
2005-06-06
The authors have developed a new computer code, RAM, to solve the conservative equations of special relativistic hydrodynamics (SRHD) using adaptive mesh refinement (AMR) on parallel computers. They have implemented a characteristic-wise, finite difference, weighted essentially non-oscillatory (WENO) scheme using the full characteristic decomposition of the SRHD equations to achieve fifth-order accuracy in space. For time integration they use the method of lines with a third-order total variation diminishing (TVD) Runge-Kutta scheme. They have also implemented fourth and fifth order Runge-Kutta time integration schemes for comparison. The implementation of AMR and parallelization is based on the FLASH code. RAM is modular and includes the capability to easily swap hydrodynamics solvers, reconstruction methods and physics modules. In addition to WENO they have implemented a finite volume module with the piecewise parabolic method (PPM) for reconstruction and the modified Marquina approximate Riemann solver to work with TVD Runge-Kutta time integration. They examine the difficulty of accurately simulating shear flows in numerical relativistic hydrodynamics codes. They show that under-resolved simulations of simple test problems with transverse velocity components produce incorrect results and demonstrate the ability of RAM to correctly solve these problems. RAM has been tested in one, two and three dimensions and in Cartesian, cylindrical and spherical coordinates. they have demonstrated fifth-order accuracy for WENO in one and two dimensions and performed detailed comparison with other schemes for which they show significantly lower convergence rates. Extensive testing is presented demonstrating the ability of RAM to address challenging open questions in relativistic astrophysics.
A decoupled energy stable scheme for a hydrodynamic phase-field ...
2015-12-02
Oct 21, 2015 ... We develop a linear, first-order, decoupled, energy-stable scheme for a binary hydrodynamic phase field model of mixtures of nematic liquid ...
Dancing Volvox: Hydrodynamic Bound States of Swimming Algae
Knut Drescher; Kyriacos C. Leptos; Idan Tuval; Takuji Ishikawa; Timothy J. Pedley; Raymond E. Goldstein
2009-01-14
The spherical alga Volvox swims by means of flagella on thousands of surface somatic cells. This geometry and its large size make it a model organism for studying the fluid dynamics of multicellularity. Remarkably, when two nearby Volvox swim close to a solid surface, they attract one another and can form stable bound states in which they "waltz" or "minuet" around each other. A surface-mediated hydrodynamic attraction combined with lubrication forces between spinning, bottom-heavy Volvox explains the formation, stability and dynamics of the bound states. These phenomena are suggested to underlie observed clustering of Volvox at surfaces.
Electron magneto-hydrodynamic waves bounded by magnetic bubble
Anitha, V. P.; Sharma, D.; Banerjee, S. P.; Mattoo, S. K. [Institute for Plasma Research, Bhat, Gandhinagar 382428 (India)
2012-08-15
The propagation of electron magneto-hydrodynamic (EMHD) waves is studied experimentally in a 3-dimensional region of low magnetic field surrounded by stronger magnetic field at its boundaries. We report observations where bounded left hand polarized Helicon like EMHD waves are excited, localized in the region of low magnetic field due to the boundary effects generated by growing strengths of the ambient magnetic field rather than a conducting or dielectric material boundary. An analytical model is developed to include the effects of radially nonuniform magnetic field in the wave propagation. The bounded solutions are compared with the experimentally obtained radial wave magnetic field profiles explaining the observed localized propagation of waves.
Maxwell-Chern-Simons Hydrodynamics for the Chiral Magnetic Effect
Sener Ozonder
2011-07-20
The rate of vacuum changing topological solutions of the gluon field, sphalerons, is estimated to be large at the typical temperatures of heavy-ion collisions, particularly at the Relativistic Heavy Ion Collider. Such windings in the gluon field are expected to produce parity-odd bubbles, which cause separation of positively and negatively charged quarks along the axis of the external magnetic field. This chiral magnetic effect can be mimicked by Chern-Simons modified electromagnetism. Here we present a model of relativistic hydrodynamics including the effects of axial anomalies via the Chern-Simons term.
Skew And Twist Resistant Hydrodynamic Rotary Shaft Seal
Dietle, Lannie (Sugar Land, TX); Kalsi, Manmohan Singh (Houston, TX)
2000-03-14
A hydrodynamically lubricated squeeze packing type rotary shaft seal suitable for lubricant retention and environmental exclusion which incorporates one or more resilient protuberances which and cooperate with the gland walls to hold the seal straight in its installation groove in unpressurized and low pressure lubricant retention applications thereby preventing skew-induced wear caused by impingement of abrasive contaminants present in the environment, and which also serve as radial bearings to prevent tipping of the seal within its installation gland. Compared to prior art, this invention provides a dramatic reduction of seal and shaft wear in abrasive environments and provides a significant increase in seal life.
On freeze-out problem in relativistic hydrodynamics
Ivanov, Yu. B., E-mail: Y.Ivanov@gsi.de; Russkikh, V. N. [Gesellschaft fuer Schwerionenforschung mbH (Germany)
2009-07-15
A finite unbound system which is equilibrium in one reference frame is in general nonequilibrium in another frame. This is a consequence of the relative character of the time synchronization in the relativistic physics. This puzzle was a prime motivation of the Cooper-Frye approach to the freeze-out in relativistic hydrodynamics. Solution of the puzzle reveals that the Cooper-Frye recipe is far not a unique phenomenological method that meets requirements of energy-momentum conservation. Alternative freeze-out recipes are considered and discussed.
Second-Order Accurate Method for Solving Radiation-Hydrodynamics
Edwards, Jarrod Douglas
2013-11-12
to hydrodynamics, shocks, and asymptotics and has generously included me in very exciting research opportunities that expanded my knowledge of the field. Over the years, his advice has been invaluable to me in my rad-hydro research. I would also like to acknowledge... method that was first derived in [2]. 1 There is actually a family of such schemes, but one member of the family can be shown to be optimal in a certain sense. In Section 3, we compare in detail a simple, near-optimal version of the TR/BDF2 method...
Hydrodynamic effects on coalescence. (Technical Report) | SciTech Connect
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Hydrodynamic Focusing Micropump Module with PDMS/Nickel Particle
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Los Alamos conducts important hydrodynamic experiment in Nevada
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AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Homesum_a_epg0_fpd_mmcf_m.xls" ,"Available from WebQuantity ofkandz-cm11 Outreach Home Room NewsInformationJesse BergkampCentermillion to local Unitedto STEMLANL conducts hydrodynamic
Multi-Thread Hydrodynamic Modeling of a Solar Flare
Harry P. Warren
2005-07-13
Past hydrodynamic simulations have been able to reproduce the high temperatures and densities characteristic of solar flares. These simulations, however, have not been able to account for the slow decay of the observed flare emission or the absence of blueshifts in high spectral resolution line profiles. Recent work has suggested that modeling a flare as an sequence of independently heated threads instead of as a single loop may resolve the discrepancies between the simulations and observations. In this paper we present a method for computing multi-thread, time-dependent hydrodynamic simulations of solar flares and apply it to observations of the Masuda flare of 1992 January 13. We show that it is possible to reproduce the temporal evolution of high temperature thermal flare plasma observed with the instruments on the \\textit{GOES} and \\textit{Yohkoh} satellites. The results from these simulations suggest that the heating time-scale for a individual thread is on the order of 200 s. Significantly shorter heating time scales (20 s) lead to very high temperatures and are inconsistent with the emission observed by \\textit{Yohkoh}.
Refining a relativistic, hydrodynamic solver: Admitting ultra-relativistic flows
J. P. Bernstein; P. A. Hughes
2009-07-23
We have undertaken the simulation of hydrodynamic flows with bulk Lorentz factors in the range 10^2--10^6. We discuss the application of an existing relativistic, hydrodynamic primitive-variable recovery algorithm to a study of pulsar winds, and, in particular, the refinement made to admit such ultra-relativistic flows. We show that an iterative quartic root finder breaks down for Lorentz factors above 10^2 and employ an analytic root finder as a solution. We find that the former, which is known to be robust for Lorentz factors up to at least 50, offers a 24% speed advantage. We demonstrate the existence of a simple diagnostic allowing for a hybrid primitives recovery algorithm that includes an automatic, real-time toggle between the iterative and analytical methods. We further determine the accuracy of the iterative and hybrid algorithms for a comprehensive selection of input parameters and demonstrate the latter's capability to elucidate the internal structure of ultra-relativistic plasmas. In particular, we discuss simulations showing that the interaction of a light, ultra-relativistic pulsar wind with a slow, dense ambient medium can give rise to asymmetry reminiscent of the Guitar nebula leading to the formation of a relativistic backflow harboring a series of internal shockwaves. The shockwaves provide thermalized energy that is available for the continued inflation of the PWN bubble. In turn, the bubble enhances the asymmetry, thereby providing positive feedback to the backflow.
Modelling the Mechanics and Hydrodynamics of Swimming E. coli
Jinglei Hu; Mingcheng Yang; Gerhard Gompper; Roland G. Winkler
2015-08-04
The swimming properties of an E. coli-type model bacterium are investigated by mesoscale hy- drodynamic simulations, combining molecular dynamics simulations of the bacterium with the multiparticle particle collision dynamics method for the embedding fluid. The bacterium is com- posed of a spherocylindrical body with attached helical flagella, built up from discrete particles for an efficient coupling with the fluid. We measure the hydrodynamic friction coefficients of the bacterium and find quantitative agreement with experimental results of swimming E. coli. The flow field of the bacterium shows a force-dipole-like pattern in the swimming plane and two vor- tices perpendicular to its swimming direction arising from counterrotation of the cell body and the flagella. By comparison with the flow field of a force dipole and rotlet dipole, we extract the force- dipole and rotlet-dipole strengths for the bacterium and find that counterrotation of the cell body and the flagella is essential for describing the near-field hydrodynamics of the bacterium.
Dynamic mesoscale model of dipolar fluids via fluctuating hydrodynamics
Persson, Rasmus A. X.; Chu, Jhih-Wei, E-mail: jwchu@nctu.edu.tw [Institute of Bioinformatics and Systems Biology, National Chiao Tung University, Hsinchu 30068, Taiwan (China); Department of Biological Science and Technology, National Chiao Tung University, Hsinchu 30068, Taiwan (China); Voulgarakis, Nikolaos K. [Department of Mathematics, Washington State University, Richland, Washington 99372 (United States)
2014-11-07
Fluctuating hydrodynamics (FHD) is a general framework of mesoscopic modeling and simulation based on conservational laws and constitutive equations of linear and nonlinear responses. However, explicit representation of electrical forces in FHD has yet to appear. In this work, we devised an Ansatz for the dynamics of dipole moment densities that is linked with the Poisson equation of the electrical potential ? in coupling to the other equations of FHD. The resulting ?-FHD equations then serve as a platform for integrating the essential forces, including electrostatics in addition to hydrodynamics, pressure-volume equation of state, surface tension, and solvent-particle interactions that govern the emergent behaviors of molecular systems at an intermediate scale. This unique merit of ?-FHD is illustrated by showing that the water dielectric function and ion hydration free energies in homogeneous and heterogenous systems can be captured accurately via the mesoscopic simulation. Furthermore, we show that the field variables of ?-FHD can be mapped from the trajectory of an all-atom molecular dynamics simulation such that model development and parametrization can be based on the information obtained at a finer-grained scale. With the aforementioned multiscale capabilities and a spatial resolution as high as 5 Å, the ?-FHD equations represent a useful semi-explicit solvent model for the modeling and simulation of complex systems, such as biomolecular machines and nanofluidics.
Bulk Viscosity and Cavitation in Boost-Invariant Hydrodynamic Expansion
Krishna Rajagopal; Nilesh Tripuraneni
2010-02-16
We solve second order relativistic hydrodynamics equations for a boost-invariant 1+1-dimensional expanding fluid with an equation of state taken from lattice calculations of the thermodynamics of strongly coupled quark-gluon plasma. We investigate the dependence of the energy density as a function of proper time on the values of the shear viscosity, the bulk viscosity, and second order coefficients, confirming that large changes in the values of the latter have negligible effects. Varying the shear viscosity between zero and a few times s/(4 pi), with s the entropy density, has significant effects, as expected based on other studies. Introducing a nonzero bulk viscosity also has significant effects. In fact, if the bulk viscosity peaks near the crossover temperature Tc to the degree indicated by recent lattice calculations in QCD without quarks, it can make the fluid cavitate -- falling apart into droplets. It is interesting to see a hydrodynamic calculation predicting its own breakdown, via cavitation, at the temperatures where hadronization is thought to occur in ultrarelativistic heavy ion collisions.
Bulk Viscosity and Cavitation in Boost-Invariant Hydrodynamic Expansion
Rajagopal, Krishna
2009-01-01
We solve second order relativistic hydrodynamics equations for a boost-invariant 1+1-dimensional expanding fluid with an equation of state taken from lattice calculations of the thermodynamics of strongly coupled quark-gluon plasma. We investigate the dependence of the energy density as a function of proper time on the values of the shear viscosity, the bulk viscosity, and second order coefficients, confirming that large changes in the values of the latter have negligible effects. Varying the shear viscosity between zero and a few times s/(4 pi), with s the entropy density, has significant effects, as expected based on other studies. Introducing a nonzero bulk viscosity also has significant effects. In fact, if the bulk viscosity peaks near the crossover temperature Tc to the degree indicated by recent lattice calculations in QCD without quarks, it can make the fluid cavitate -- falling apart into droplets. It is interesting to see a hydrodynamic calculation predicting its own breakdown, via cavitation, at th...
Radiation Hydrodynamics Test Problems with Linear Velocity Profiles
Hendon, Raymond C. [Los Alamos National Laboratory; Ramsey, Scott D. [Los Alamos National Laboratory
2012-08-22
As an extension of the works of Coggeshall and Ramsey, a class of analytic solutions to the radiation hydrodynamics equations is derived for code verification purposes. These solutions are valid under assumptions including diffusive radiation transport, a polytropic gas equation of state, constant conductivity, separable flow velocity proportional to the curvilinear radial coordinate, and divergence-free heat flux. In accordance with these assumptions, the derived solution class is mathematically invariant with respect to the presence of radiative heat conduction, and thus represents a solution to the compressible flow (Euler) equations with or without conduction terms included. With this solution class, a quantitative code verification study (using spatial convergence rates) is performed for the cell-centered, finite volume, Eulerian compressible flow code xRAGE developed at Los Alamos National Laboratory. Simulation results show near second order spatial convergence in all physical variables when using the hydrodynamics solver only, consistent with that solver's underlying order of accuracy. However, contrary to the mathematical properties of the solution class, when heat conduction algorithms are enabled the calculation does not converge to the analytic solution.
Hydrodynamic model for electron-hole plasma in graphene
D. Svintsov; V. Vyurkov; S. Yurchenko; T. Otsuji; V. Ryzhii
2012-01-03
We propose a hydrodynamic model describing steady-state and dynamic electron and hole transport properties of graphene structures which accounts for the features of the electron and hole spectra. It is intended for electron-hole plasma in graphene characterized by high rate of intercarrier scattering compared to external scattering (on phonons and impurities), i.e., for intrinsic or optically pumped (bipolar plasma), and gated graphene (virtually monopolar plasma). We demonstrate that the effect of strong interaction of electrons and holes on their transport can be treated as a viscous friction between the electron and hole components. We apply the developed model for the calculations of the graphene dc conductivity, in particular, the effect of mutual drag of electrons and holes is described. The spectra and damping of collective excitations in graphene in the bipolar and monopolar limits are found. It is shown that at high gate voltages and, hence, at high electron and low hole densities (or vice-versa), the excitations are associated with the self-consistent electric field and the hydrodynamic pressure (plasma waves). In intrinsic and optically pumped graphene, the waves constitute quasineutral perturbations of the electron and hole densities (electron-hole sound waves) with the velocity being dependent only on the fundamental graphene constants.
Numerical simulation of the hydrodynamical combustion to strange quark matter
Niebergal, Brian; Ouyed, Rachid; Jaikumar, Prashanth
2010-12-15
We present results from a numerical solution to the burning of neutron matter inside a cold neutron star into stable u,d,s quark matter. Our method solves hydrodynamical flow equations in one dimension with neutrino emission from weak equilibrating reactions, and strange quark diffusion across the burning front. We also include entropy change from heat released in forming the stable quark phase. Our numerical results suggest burning front laminar speeds of 0.002-0.04 times the speed of light, much faster than previous estimates derived using only a reactive-diffusive description. Analytic solutions to hydrodynamical jump conditions with a temperature-dependent equation of state agree very well with our numerical findings for fluid velocities. The most important effect of neutrino cooling is that the conversion front stalls at lower density (below {approx_equal}2 times saturation density). In a two-dimensional setting, such rapid speeds and neutrino cooling may allow for a flame wrinkle instability to develop, possibly leading to detonation.
Hydrodynamic and hydromagnetic energy spectra from large eddy simulations
N. E. L. Haugen; A. Brandenburg
2006-06-29
Direct and large eddy simulations of hydrodynamic and hydromagnetic turbulence have been performed in an attempt to isolate artifacts from real and possibly asymptotic features in the energy spectra. It is shown that in a hydrodynamic turbulence simulation with a Smagorinsky subgrid scale model using 512^3 meshpoints two important features of the 4096^3 simulation on the Earth simulator (Kaneda et al. 2003, Phys. Fluids 15, L21) are reproduced: a k^{-0.1} correction to the inertial range with a k^{-5/3} Kolmogorov slope and the form of the bottleneck just before the dissipative subrange. Furthermore, it is shown that, while a Smagorinsky-type model for the induction equation causes an artificial and unacceptable reduction in the dynamo efficiency, hyper-resistivity yields good agreement with direct simulations. In the large-scale part of the inertial range, an excess of the spectral magnetic energy over the spectral kinetic energy is confirmed. However, a trend towards spectral equipartition at smaller scales in the inertial range can be identified. With magnetic fields, no explicit bottleneck effect is seen.
The dynamics of polymers in solution with hydrodynamic memory
V. Lisy; J. Tothova; B. Brutovsky; A. V Zatovsky
2005-09-15
The theory of the dynamics of polymers in solution is developed coming from the hydrodynamic theory of the Brownian motion (BM) and the Rouse-Zimm (RZ) model. It is shown that the time correlation functions describing the polymer motion essentially differ from those in the previous RZ models based on the Einstein theory of BM. The MSD of the polymer coil is at short times proportional to t^2 (instead of t). At long times it contains additional (to the Einstein term) contributions, the leading of which is ~ t^{1/2}. The relaxation of the internal normal modes of the polymer differs from the traditional exponential decay. This is displayed in the tails of their correlation functions, the longest-lived being ~ t^{-3/2} in the Rouse limit and t^{-5/2} in the Zimm case when the hydrodynamic interaction is strong. It is discussed that the found peculiarities, in particular a slower diffusion of the coil, should be observable in dynamic scattering experiments. The dynamic structure factor and the first cumulant of the polymer coil are calculated. The theory is extended to the situation when the dynamics of the studied polymer is influenced by the presence of other polymers in dilute solution.
Hydrodynamic forces due to waves and a current induced on a pipeline placed in an open trench
Lee, Jaeyoung
1991-01-01
HYDRODYNAMIC FORCES DUE TO WAVES AND A CURRENT INDUCED ON A PIPELINE PLACED IN AN OPEN TRENCH A Thesis by JAEYOUNG LEE Submitted to the Office of Graduate Studies of Texas A&M University in partial fulfillment of the requirements... for the degree of MASTER OF SCIENCE December 1991 Major Subject: Ocean Engineering HYDRODYNAMIC FORCES DUE TO WAVES AND A CURRENT INDUCED ON A PIPELINE PLACED IN AN OPEN TRENCH A Thesis by JAEYOUNG LEE Approved as to style and content by: John B...
Falcke, Heino
of the wind's kinetic energy at the disk's surface. In applying our results to the Galactic Center black holeAccretion Disk Evolution with Wind Infall II. Results of 3D Hydrodynamical Simulations, Auf dem HÂ¨ugel 69, DÂ53121, Bonn, Germany. (hfalcke@mpifrÂbonn.mpg.de) Steward Observatory, University
Alvaro Domínguez
2014-10-10
It has been shown recently that the coefficient of collective diffusion in a colloidal monolayer is divergent due to the hydrodynamic interactions mediated by the ambient fluid in bulk. The analysis is extended to allow for time--dependent hydrodynamic interactions. Novel observational features specific to this time dependency are predicted. The possible experimental detection in the dynamics of the monolayer is discussed.
Cross, J. E.; Gregori, G. [Clarendon Laboratory, University of Oxford, Parks Road, Oxford OX1 3PU (United Kingdom); Reville, B., E-mail: j.e.cross@physics.ox.ac.uk [Centre for Plasma Physics, Queen's University Belfast, University Road, Belfast BT7 1NN (United Kingdom)
2014-11-01
We introduce the equations of magneto-quantum-radiative hydrodynamics. By rewriting them in a dimensionless form, we obtain a set of parameters that describe scale-dependent ratios of characteristic hydrodynamic quantities. We discuss how these dimensionless parameters relate to the scaling between astrophysical observations and laboratory experiments.
Jones, Douglas L.
augment sonar and vision systems. We show that the artificial lateral line can successfully perform dipoleDistant touch hydrodynamic imaging with an artificial lateral line Coombs, Douglas L. Jones reprints, see: Notes: #12;Distant touch hydrodynamic imaging with an artificial lateral line Yingchen Yang
Shashkov, Mikhail
A Pressure Relaxation Closure Model for One-Dimensional, Two-Material Lagrangian Hydrodynamics Laboratory, Los Alamos, NM USA Abstract. Despite decades of development, Lagrangian hydrodynamics of strength of assigning sub-cell pressures to the physics associ- ated with the local, dynamic evolution. We package our
Hydrodynamic modeling of tsunamis from the Currituck landslide Eric L. Geist a,
Lynett, Patrick
Hydrodynamic modeling of tsunamis from the Currituck landslide Eric L. Geist a, , Patrick J. Lynett: Accepted 24 September 2008 Keywords: tsunami landslide hydrodynamic runup numerical model sensitivity analysis Tsunami generation from the Currituck landslide offshore North Carolina and propagation of waves
Hydrodynamic oscillations and tunable swimming speed in squirmers close to repulsive walls
Lintuvuori, Juho S; Stratford, Kevin; Marenduzzo, Davide
2015-01-01
We present a lattice Boltzmann study of the hydrodynamics of a fully resolved squirmer, radius R, confined in a slab of fluid between two no-slip walls. We show that the coupling between hydrodynamics and short-range repulsive interactions between the swimmer and the surface can lead to hydrodynamic trapping of both pushers and pullers at the wall, and to hydrodynamic oscillations in the case of a pusher. We further show that a pusher moves significantly faster when close to a surface than in the bulk, whereas a puller undergoes a transition between fast motion and a dynamical standstill according to the range of the repulsive interaction. Our results critically require near-field hydrodynamics; they further suggest that it should be possible to control density and speed of squirmers at a surface by tuning the range of steric and electrostatic swimmer-wall interactions.
. Environmental engineering, mixing and transport, water quality, ocean thermal energy conversion, hydrogen. GENO engineering, hydrodynamics, computational methods, water wave mechanics, sediment transport. R. CENGIZ ERTEKIN Professor, PhD 1984, UC Berkeley. Hydrodynamics/elasticity, computational methods, nonlinear water waves
Hydrodynamics of the physical vacuum: dark matter is an illusion
Sbitnev, Valeriy I
2015-01-01
The relativistic hydrodynamical equations are being examined with the aim of extracting the quantum-mechanical equations (the relativistic Klein-Gordon equation and the Schr\\"odinger equation in the non-relativistic limit). In both cases it is required to get the quantum potential, which follows from pressure gradients within a superfluid vacuum medium. This special fluid, endowed with viscosity allows to describe emergence of the flat orbital speeds of spiral galaxies. The viscosity averaged on time vanishes, but its variance is different from zero. It is a function fluctuating about zero. Therefore the flattening is the result of the energy exchange of the torque with zero-point fluctuations of the physical vacuum on the ultra-low frequencies.
Hydrodynamics of stratified epithelium: steady state and linearized dynamics
Wei-Ting Yeh; Hsuan-Yi Chen
2015-08-07
A theoretical model for stratified epithelium is presented. The viscoelastic properties of the tissue is assumed to be dependent on the spatial distribution of proliferative and differentiated cells. Based on this assumption, a hydrodynamic description for tissue dynamics at long-wavelength, long-time limit is developed, and the analysis reveals important insight for the dynamics of an epithelium close to its steady state. When the proliferative cells occupy a thin region close to the basal membrane, the relaxation rate towards the steady state is enhanced by cell division and cell apoptosis. On the other hand, when the region where proliferative cells reside becomes sufficiently thick, a flow induced by cell apoptosis close to the apical surface could enhance small perturbations. This destabilizing mechanism is general for continuous self-renewal multi-layered tissues, it could be related to the origin of certain tissue morphology and developing pattern.
Hydro-dynamical models for the chaotic dripping faucet
P. Coullet; L. Mahadevan; C. S. Riera
2004-08-20
We give a hydrodynamical explanation for the chaotic behaviour of a dripping faucet using the results of the stability analysis of a static pendant drop and a proper orthogonal decomposition (POD) of the complete dynamics. We find that the only relevant modes are the two classical normal forms associated with a Saddle-Node-Andronov bifurcation and a Shilnikov homoclinic bifurcation. This allows us to construct a hierarchy of reduced order models including maps and ordinary differential equations which are able to qualitatively explain prior experiments and numerical simulations of the governing partial differential equations and provide an explanation for the complexity in dripping. We also provide a new mechanical analogue for the dripping faucet and a simple rationale for the transition from dripping to jetting modes in the flow from a faucet.
Hydro-dynamical models for the chaotic dripping faucet
Coullet, P; Riera, C S
2004-01-01
We give a hydrodynamical explanation for the chaotic behaviour of a dripping faucet using the results of the stability analysis of a static pendant drop and a proper orthogonal decomposition (POD) of the complete dynamics. We find that the only relevant modes are the two classical normal forms associated with a Saddle-Node-Andronov bifurcation and a Shilnikov homoclinic bifurcation. This allows us to construct a hierarchy of reduced order models including maps and ordinary differential equations which are able to qualitatively explain prior experiments and numerical simulations of the governing partial differential equations and provide an explanation for the complexity in dripping. We also provide a new mechanical analogue for the dripping faucet and a simple rationale for the transition from dripping to jetting modes in the flow from a faucet.
Hydrodynamic analysis of laser-driven cylindrical implosions
Ramis, R. [E.T.S.I. Aeronáuticos, Universidad Politécnica de Madrid (Spain)] [E.T.S.I. Aeronáuticos, Universidad Politécnica de Madrid (Spain)
2013-08-15
Three-dimensional hydrodynamic simulations are performed to study laser-driven cylindrical implosions in the context of experiments (F. Perez et al., Plasma Phys. Controlled Fusion 51, 124035 (2009)) carried out at the Rutherford Appleton Laboratory in the framework of the HiPER project. The analysis is carried out by using the 3D version of the hydrocode MULTI (R. Ramis et al., Comput. Phys. Commun. 49, 475-505 (1988)). The influence of the main laser parameters on implosion performance and symmetry is consistently studied and compared with the results of 2D analysis. Furthermore, the effects of uncertainties in laser irradiation (pointing, focusing, power balance, and time jitter) on implosion performance (average peak density and temperature) are studied by means of statistical analysis.
Hydrodynamics of the physical vacuum: dark matter is an illusion
Valeriy I. Sbitnev
2015-06-23
The relativistic hydrodynamical equations are being examined with the aim of extracting the quantum-mechanical equations (the relativistic Klein-Gordon equation and the Schr\\"odinger equation in the non-relativistic limit). In both cases it is required to get the quantum potential, which follows from pressure gradients within a superfluid vacuum medium. This special fluid, endowed with viscosity allows to describe emergence of the flat orbital speeds of spiral galaxies. The viscosity averaged on time vanishes, but its variance is different from zero. It is a function fluctuating about zero. Therefore the flattening is the result of the energy exchange of the torque with zero-point fluctuations of the physical vacuum on the ultra-low frequencies.
Flow harmonics within an analytically solvable viscous hydrodynamic model
Yoshitaka Hatta; Jorge Noronha; Giorgio Torrieri; Bo-Wen Xiao
2014-10-01
Based on a viscous hydrodynamic model with anisotropically perturbed Gubser flow and isothermal Cooper-Frye freezeout at early times, we analytically compute the flow harmonics $v_n(p_T)$ and study how they scale with the harmonic number $n$ and transverse momentum, as well as the system size, shear and bulk viscosity coefficients, and collision energy. In particular, we find that the magnitude of shear viscous corrections grows linearly with $n$. The mixing between different harmonics is also discussed. While this model is rather simple as compared to realistic heavy-ion collisions, we argue that the scaling results presented here may be meaningfully compared to experimental data collected over many energies, system sizes, and geometries.
Anisotropic flow in transport+hydrodynamics hybrid approaches
Hannah Petersen
2014-11-26
This contribution to the focus issue covers anisotropic flow in hybrid approaches. The historical development of hybrid approaches and their impact on the interpretation of flow measurements is reviewed. The major ingredients of a hybrid approach and the transition criteria between transport and hydrodynamics are discussed. The results for anisotropic flow in (event-by-event) hybrid approaches are presented. Some hybrid approaches rely on hadronic transport for the late stages for the reaction (so called afterburner) and others employ transport approaches for the early non equilibrium evolution. In addition, there are 'full' hybrid calculations where a fluid evolution is dynamically embedded in a transport simulation. After demonstrating the success of hybrid approaches at high RHIC and LHC energies, existing hybrid caluclations for collective flow observables at lower beam energies are discussed and remaining challenges outlined.
Quasi-periodic oscillations from relativistic hydrodynamical slender tori
Mishra, B; Manousakis, A; Fragile, P C; Paumard, T; Klu?niak, W
2015-01-01
We simulate an oscillating purely hydrodynamical torus with constant specific angular mo- mentum around a Schwarzschild black hole. The goal is to search for quasi-periodic oscil- lations (QPOs) in the light curve of the torus. The initial torus setup is subjected to radial, vertical and diagonal (combination of radial and vertical) velocity perturbations. The hydro- dynamical simulations are performed using the general relativistic magnetohydrodynamics code Cosmos++ and ray-traced using the GYOTO code. We found that a horizontal velocity perturbation triggers the radial and plus modes, while a vertical velocity perturbation trig- gers the vertical and X modes. The diagonal perturbation gives a combination of the modes triggered in the radial and vertical perturbations.
Hydrodynamic instabilities in shear flows of cohesive granular particles
Kuniyasu Saitoh; Satoshi Takada; Hisao Hayakawa
2015-05-15
We extend the dynamic van der Waals model introduced by A. Onuki [Phys. Rev. Lett. 94, 054501 (2005)] to the description of cohesive granular flows under a plane shear to study their hydrodynamic instabilities. Numerically solving the dynamic van der Waals model, we observe various heterogeneous structures of the density in steady states, where the viscous heating is balanced with the energy dissipation caused by inelastic collisions. Based on the linear stability analysis, we find that the spatial structures are determined by the mean volume fraction, the applied shear rate, and the inelasticity, where the instability is triggered if the system is thermodynamically unstable, i.e. the pressure, $p$, and the volume fraction, $\\phi$, satisfy $\\partial p/\\partial\\phi<0$.
An Eulerian PPM & PIC Code for Cosmological Hydrodynamics
A. Sornborger; B. Fryxell; K. Olson; P. MacNeice
1996-08-05
We present a method for integrating the cosmological hydrodynamical equations including a collisionless dark matter component. For modelling the baryonic matter component, we use the Piecewise Parabolic Method (PPM) which is a high-accuracy shock capturing technique. The dark matter component is modeled using gravitationally interacting particles whose evolution is determined using standard particle-in-cell techniques. We discuss details of the inclusion of gravity and expansion in the PPM code and give results of a number of tests of the code. This code has been developed for a massively parallel, SIMD supercomputer: the MasPar MP-2 parallel processor. We present details of the techniques we have used to implement the code for this architecture and discuss performance of the code on the MP-2. The code processes $5.0 \\times 10^4$ grid zones per second and requires 53 seconds of machine time for a single timestep in a $128^3$ simulation.
Simulated VLBI Images From Relativistic Hydrodynamic Jet Models
Amy J. Mioduszewski; Philip A. Hughes; G. Comer Duncan
1996-06-03
A series of simulated maps showing the appearance in total intensity of flows computed using a recently developed relativistic hydrodynamic code (Duncan \\& Hughes 1994: ApJ, 436, L119) are presented. The radiation transfer calculations were performed by assuming the flow is permeated by a magnetic field and fast particle distribution in energy equipartition, with energy density proportional to the hydrodynamic energy density (i.e., pressure). We find that relativistic flows subject to strong perturbations exhibit a density structure consisting of a series of nested bow shocks, and that this structure is evident in the intensity maps for large viewing angles. However, for viewing angles $<30^{\\circ}$, differential Doppler boosting leads to a series of axial knots of emission, similar to the pattern exhibited by many VLBI sources. The appearance of VLBI knots is determined primarily by the Doppler boosting of parts of a more extended flow. To study the evolution of a perturbed jet, a time series of maps was produced and an integrated flux light curve created. The light curve shows features characteristic of a radio loud AGN: small amplitude variations and a large outburst. We find that in the absence of perturbations, jets with a modest Lorentz factor ($\\sim 5$) exhibit complex intensity maps, while faster jets (Lorentz factor $\\sim 10$) are largely featureless. We also study the appearance of kiloparsec jet-counterjet pairs by producing simulated maps at relatively large viewing angles; we conclude that observed hot spot emission is more likely to be associated with the Mach disk than with the outer, bow shock.
Hydrodynamical Description of the QCD Dirac Spectrum at Finite Chemical Potential
Liu, Yizhuang; Zahed, Ismail
2015-01-01
We present a hydrodynamical description of the QCD Dirac spectrum at finite chemical potential as an uncompressible droplet in the complex eigenvalue space. For a large droplet, the fluctuation spectrum around the hydrostatic solution is gapped by a longitudinal Coulomb plasmon, and exhibits a frictionless odd viscosity. The stochastic relaxation time for the restoration/breaking of chiral symmetry is set by twice the plasmon frequency. The leading droplet size correction to the relaxation time is fixed by a universal odd viscosity to density ratio $\\eta_O/\\rho_0=(\\beta-1)/2$ for the three Dyson ensembles $\\beta=1,2,4$.
Dudukovic, M.P.; Fan, L.S.; Chang, Min
1997-05-01
The objective of this cooperative research effort between Washington University, Ohio State University and Exxon Research and Engineering Company is to improve the basis for scale-up and operation of slurry bubble column reactors for syngas conversion and other coal conversion processes by increased reliance on experimentally verified hydrodynamic models. The first year of this three year program was spent on developing and tuning the experimental tools that can provide accurate measurement of pertinent hydrodynamic quantities, such as velocity field and holdup distribution, for validation of hydrodynamic models. Advances made in preparing the unique Computer Automated Radioactive Particle Tracing (CARPT) technique for use in high pressure systems are described in this report The work done on developing a reliable beat transfer coefficient measurement probe at operating conditions of interest is also described. Finally, the work done in preparing the Exxon pilot plant facilities for high pressure runs and pertinent hydrodynamic measurements is outlined together with preliminary studies of matching the fluid dynamics program predictions and data in a two dimensional column.
Effect of Second-Order Hydrodynamics on a Floating Offshore Wind Turbine
Roald, L.; Jonkman, J.; Robertson, A.
2014-05-01
The design of offshore floating wind turbines uses design codes that can simulate the entire coupled system behavior. At the present, most codes include only first-order hydrodynamics, which induce forces and motions varying with the same frequency as the incident waves. Effects due to second- and higher-order hydrodynamics are often ignored in the offshore industry, because the forces induced typically are smaller than the first-order forces. In this report, first- and second-order hydrodynamic analysis used in the offshore oil and gas industry is applied to two different wind turbine concepts--a spar and a tension leg platform.
Rajarshi Chakrabarti
2011-05-04
Based on the Wilemski-Fixman approach (J. Chem. Phys. 60, 866 (1974)) we showed that for a flexible chain in theta solvent hydrodynamic interaction treated with an pre-averaging approximation makes ring closing faster if the chain is not very short. Only for a very short chain the ring closing is slower with hydrodynamic interaction on. We have also shown that the ring closing time for a chain with hydrodynamic interaction in theta solvent scales with the chain length (N) as N^(1.527), in good agreement with previous renormalization group calculation based prediction by Freidman et al. (Phys. Rev. A. 40, 5950 (1989)).
Importance of hydrodynamic shielding for the dynamic behavior of short polyelectrolyte chains
Kai Grass; Ute Böhme; Ulrich Scheler; Hervé Cottet; Christian Holm
2008-05-14
The dynamic behavior of polyelectrolyte chains in the oligomer range is investigated with coarse-grained molecular dynamics simulation and compared to data obtained by two different experimental methods, namely capillary electrophoresis and electrophoresis NMR. We find excellent agreement of experiments and simulations when hydrodynamic interactions are accounted for in the simulations. We show that the electrophoretic mobility exhibits a maximum in the oligomer range and for the first time illustrate that this maximum is due to the hydrodynamical shielding between the chain monomers. Our findings demonstrate convincingly that it is possible to model dynamic behavior of polyelectrolytes using coarse grained models for both, the polyelectrolyte chains and the solvent induced hydrodynamic interactions.
Goldstein, Raymond E.
Hydrodynamic Synchronization and Metachronal Waves on the Surface of the Colonial Alga Volvox of metachronal waves on the surface of the colonial alga Volvox carteri, whose large size and ease
Purely hydrodynamic ordering of rotating disks at a finite Reynolds number
Goto, Yusuke
2015-01-01
Self-organization of moving objects in hydrodynamic environments has recently attracted considerable attention in connection to natural phenomena and living systems. However, the underlying physical mechanism is much less clear due to the intrinsically nonequilibrium nature, compared with self-organization of thermal systems. Hydrodynamic interactions are believed to play a crucial role in such phenomena. To elucidate the fundamental physical nature of many-body hydrodynamic interactions at a finite Reynolds number, here we study a system of co-rotating hard disks in a two-dimensional viscous fluid at zero temperature. Despite the absence of thermal noise, this system exhibits rich phase behaviours, including a fluid state with diffusive dynamics, a cluster state, a hexatic state, a glassy state, a plastic crystal state and phase demixing.We reveal that these behaviours are induced by the off-axis and many-body nature of nonlinear hydrodynamic interactions and the finite time required for propagating the inte...
Hydrodynamic growth of shell modulations in the deceleration phase of spherical direct. Se´guin Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge .2 The unstable growth of target nonuniformities is the most significant factor disrupting
Maertens, Audrey (Audrey Paulette Solange)
2015-01-01
When walking, driving or riding a bicycle, we mostly rely on vision to avoid obstacles and evaluate optimal paths. Underwater, vision is usually limited, but flow structures resulting from the hydrodynamic interactions ...
Lu, Chang
Characterizing osmotic lysis kinetics under microfluidic hydrodynamic focusing for erythrocyte microfluidic tool for examining erythrocyte fragility based on characterizing osmotic lysis kinetics deformability include osmotic fragility tests,1820 filtration,21,22 ektacytometry,2325 rheoscopy,26
Measurements of static loading characteristics of a Flexurepivot Tilt Pad Hydrodynamic Bearing
Walton, Nicholas Van Edward
1995-01-01
An experimental investigation examining the static loading characteristics of a four-pad, KMC FLEXUREPIVOT Tilt Pad Hydrodynamic Bearing is presented. Tests are conducted on the TRACE Fluid Film Bearing Element Test Rig for journal speeds ranging...
Physico-chemical hydrodynamics of droplets on textured surfaces with engineered micro/nanostructures
Park, Kyoo Chul
2013-01-01
Understanding physico-chemical hydrodynamics of droplets on textured surfaces is of fundamental and practical significance for designing a diverse range of engineered surfaces such as low-reflective, self-cleaning or ...
Matha, D.; Schlipf, M.; Cordle, A.; Pereira, R.; Jonkman, J.
2011-10-01
This paper presents the current major modeling challenges for floating offshore wind turbine design tools and describes aerodynamic and hydrodynamic effects due to rotor and platform motions and usage of non-slender support structures.
Mendelson, Leah Rose
2013-01-01
Abstract This thesis details the implementation of a three-dimensional PIV system to study the hydrodynamics of freely swimming Giant Danio (Danio aequipinnatus). Volumetric particle fields are reconstructed using synthetic ...
Pandoe, Wahyu Widodo
2004-09-30
provides a basis for determining how the water circulation three-dimensionally controls the hydrodynamics of the system and ultimately transports the suspended and soluble materials due to combined currents and waves. A three-dimensional circulation model...
Using Genetic Algorithms to Optimize Bathymetric Surveys for Hydrodynamic Model Input
Manian, Dinesh
2010-07-14
The first part of this thesis deals with studying the effect of the specified bathymetric resolution and ideal bathymetric form parameters on the output from the wave and hydrodynamic modules of Delft-3D. This thesis then describes the use...
Venkataraman, Balaji
1995-01-01
of these pumps depend significantly on the rotordynamic features of hardware elements such as the seals and bearings. The focus of this research effort is to develop a comprehensive thermo-elasto-hydrodynamic analysis of turbulent liquid annular seals...
The hydrodynamic stability of crossflow vortices in the Bdewadt boundary layer
The hydrodynamic stability of crossflow vortices in the Bödewadt boundary layer N. A. Culverhouse the critical Reynolds number. extends the laminar flow region. decreasing the magnitude of the crossflow
Laverty, Stephen Michael
2005-01-01
This thesis looks at the hydrodynamics of spherical projectiles impacting the free surface using a unique experimental WebLab facility. Experiments were performed to determine the force impact coefficients of spheres and ...
Hydrodynamics and heat transfer during flow boiling instabilities in a single microchannel
Aussillous, Pascale
Hydrodynamics and heat transfer during flow boiling instabilities in a single microchannel July 2008 Keywords: Boiling Microchannels Visualisation Flow boiling instabilities Heat transfer a b intensification heat removal. Flow boiling heat transfer in microchannel geometry and the associated flow
Hydrodynamically-driven colloidal assembly in the thin-film entrainment regime
Carlos E. Colosqui; Jeffrey F. Morris; Howard A. Stone
2012-10-01
We study numerically the hydrodynamics of dip coating from a suspension and report a mechanism for colloidal assembly and pattern formation on smooth and uniform substrates. Below a critical withdrawal speed of the substrate, capillary forces required to deform the meniscus prevent colloidal particles from entering the coating film. Capillary forces are overcome by hydrodynamic drag only after a minimum number of particles organize in a close-packed formation within the meniscus. Once within the film, the formed assembly moves at nearly the withdrawal speed and rapidly separates from the next assembly. The interplay between hydrodynamic and capillary forces can thus produce periodic and regular structures within the curved meniscus that extends below the withdrawn film. The hydrodynamically-driven assembly documented here is consistent with stripe pattern formations observed experimentally in the so-called thin-film entrainment regime.
A Model for the Dynamic User-Equilibrium Problem Using a Hydrodynamic Theory Approach
Perakis, Georgia
In this paper we study the dynamic user-equilibrium problem. The development of Intelligent Vehicle Highway Systems (IVHS) has made this problem very popular in the recent years. In this paper we take a hydrodynamic theory ...
Driven cavity flow: from molecular dynamics to continuum hydrodynamics
Tiezheng Qian; Xiao-Ping Wang
2004-03-06
Molecular dynamics (MD) simulations have been carried out to investigate the slip of fluid in the lid driven cavity flow where the no-slip boundary condition causes unphysical stress divergence. The MD results not only show the existence of fluid slip but also verify the validity of the Navier slip boundary condition. To better understand the fluid slip in this problem, a continuum hydrodynamic model has been formulated based upon the MD verification of the Navier boundary condition and the Newtonian stress. Our model has no adjustable parameter because all the material parameters (density, viscosity, and slip length) are directly determined from MD simulations. Steady-state velocity fields from continuum calculations are in quantitative agreement with those from MD simulations, from the molecular-scale structure to the global flow. The main discovery is as follows. In the immediate vicinity of the corners where moving and fixed solid surfaces intersect, there is a core partial-slip region where the slippage is large at the moving solid surface and decays away from the intersection quickly. In particular, the structure of this core region is nearly independent of the system size. On the other hand, for sufficiently large system, an additional partial-slip region appears where the slippage varies as $1/r$ with $r$ denoting the distance from the corner along the moving solid surface. The existence of this wide power-law region is in accordance with the asymptotic $1/r$ variation of stress and the Navier boundary condition.
Simulating Magnetized Laboratory Plasmas with Smoothed Particle Hydrodynamics
Johnson, J N
2009-07-02
The creation of plasmas in the laboratory continues to generate excitement in the physics community. Despite the best efforts of the intrepid plasma diagnostics community, the dynamics of these plasmas remains a difficult challenge to both the theorist and the experimentalist. This dissertation describes the simulation of strongly magnetized laboratory plasmas with Smoothed Particle Hydrodynamics (SPH), a method born of astrophysics but gaining broad support in the engineering community. We describe the mathematical formulation that best characterizes a strongly magnetized plasma under our circumstances of interest, and we review the SPH method and its application to astrophysical plasmas based on research by Phillips [1], Buerve [2], and Price and Monaghan [3]. Some modifications and extensions to this method are necessary to simulate terrestrial plasmas, such as a treatment of magnetic diffusion based on work by Brookshaw [4] and by Atluri [5]; we describe these changes as we turn our attention toward laboratory experiments. Test problems that verify the method are provided throughout the discussion. Finally, we apply our method to the compression of a magnetized plasma performed by the Compact Toroid Injection eXperiment (CTIX) [6] and show that the experimental results support our computed predictions.
A DENSITY-INDEPENDENT FORMULATION OF SMOOTHED PARTICLE HYDRODYNAMICS
Saitoh, Takayuki R.; Makino, Junichiro
2013-05-01
The standard formulation of the smoothed particle hydrodynamics (SPH) assumes that the local density distribution is differentiable. This assumption is used to derive the spatial derivatives of other quantities. However, this assumption breaks down at the contact discontinuity. At the contact discontinuity, the density of the low-density side is overestimated while that of the high-density side is underestimated. As a result, the pressure of the low-density (high-density) side is overestimated (underestimated). Thus, unphysical repulsive force appears at the contact discontinuity, resulting in the effective surface tension. This tension suppresses fluid instabilities. In this paper, we present a new formulation of SPH, which does not require the differentiability of density. Instead of the mass density, we adopt the internal energy density (pressure) and its arbitrary function, which are smoothed quantities at the contact discontinuity, as the volume element used for the kernel integration. We call this new formulation density-independent SPH (DISPH). It handles the contact discontinuity without numerical problems. The results of standard tests such as the shock tube, Kelvin-Helmholtz and Rayleigh-Taylor instabilities, point-like explosion, and blob tests are all very favorable to DISPH. We conclude that DISPH solved most of the known difficulties of the standard SPH, without introducing additional numerical diffusion or breaking the exact force symmetry or energy conservation. Our new SPH includes the formulation proposed by Ritchie and Thomas as a special case. Our formulation can be extended to handle a non-ideal gas easily.
Thermal and hydrodynamic effects in the ordering of lamellar fluids
G. Gonnella; A. Lamura; A. Tiribocchi
2011-02-15
Phase separation in a complex fluid with lamellar order has been studied in the case of cold thermal fronts propagating diffusively from external walls. The velocity hydrodynamic modes are taken into account by coupling the convection-diffusion equation for the order parameter to a generalised Navier-Stokes equation. The dynamical equations are simulated by implementing a hybrid method based on a lattice Boltzmann algorithm coupled to finite difference schemes. Simulations show that the ordering process occurs with morphologies depending on the speed of the thermal fronts or, equivalently, on the value of the thermal conductivity {\\xi}. At large value of {\\xi}, as in instantaneous quenching, the system is frozen in entangled configurations at high viscosity while consists of grains with well ordered lamellae at low viscosity. By decreasing the value of {\\xi}, a regime with very ordered lamellae parallel to the thermal fronts is found. At very low values of {\\xi} the preferred orientation is perpendicular to the walls in d = 2, while perpendicular order is lost moving far from the walls in d = 3.
Entropy production in non-equilibrium fluctuating hydrodynamics
Giacomo Gradenigo; Andrea Puglisi; Alessandro Sarracino
2012-05-16
Fluctuating entropy production is studied for a set of linearly coupled complex fields. The general result is applied to non-equilibrium fluctuating hydrodynamic equations for coarse-grained fields (density, temperature and velocity), in the framework of model granular fluids. We find that the average entropy production, obtained from the microscopic stochastic description, can be expressed in terms of macroscopic quantities, in analogy with linear non-equilibrium thermodynamics. We consider the specific cases of driven granular fluids with two different kinds of thermostat and the homogeneous cooling regime. In all cases, the average entropy production turns out to be the product of a thermodynamic force and a current: the former depends on the specific energy injection mechanism, the latter takes always the form of a static correlation between fluctuations of density and temperature time-derivative. Both vanish in the elastic limit. The behavior of the entropy production is studied at different length scales and the qualitative differences arising for the different granular models are discussed.
Onset and cessation of motion in hydrodynamically sheared granular beds
Abram H. Clark; Mark D. Shattuck; Nicholas T. Ouellette; Corey S. O'Hern
2015-10-06
We performed molecular dynamics simulations of granular beds driven by a model hydrodynamic shear flow to elucidate general grain-scale mechanisms that determine the onset and cessation of sediment transport. By varying the Shields number (the nondimensional shear stress at the top of the bed) and particle Reynolds number (the ratio of particle inertia to viscous damping), we explore how variations of the fluid flow rate, particle inertia, and fluid viscosity affect the onset and cessation of bed motion. For low to moderate particle Reynolds numbers, a critical boundary separates mobile and static states. Transition times between these states diverge as this boundary is approached both from above and below. At high particle Reynolds number, inertial effects become dominant, and particle motion can be sustained well below flow rates at which mobilization of a static bed occurs. We also find that the onset of bed motion (for both low and high particle Reynolds numbers) is described by Weibullian weakest-link statistics, and thus is crucially dependent on the packing structure of the granular bed, even deep beneath the surface.
Density-shear instability in electron magneto-hydrodynamics
Wood, T. S. Hollerbach, R.; Lyutikov, M.
2014-05-15
We discuss a novel instability in inertia-less electron magneto-hydrodynamics (EMHD), which arises from a combination of electron velocity shear and electron density gradients. The unstable modes have a lengthscale longer than the transverse density scale, and a growth-rate of the order of the inverse Hall timescale. We suggest that this density-shear instability may be of importance in magnetic reconnection regions on scales smaller than the ion skin depth, and in neutron star crusts. We demonstrate that the so-called Hall drift instability, previously argued to be relevant in neutron star crusts, is a resistive tearing instability rather than an instability of the Hall term itself. We argue that the density-shear instability is of greater significance in neutron stars than the tearing instability, because it generally has a faster growth-rate and is less sensitive to geometry and boundary conditions. We prove that, for uniform electron density, EMHD is “at least as stable” as regular, incompressible MHD, in the sense that any field configuration that is stable in MHD is also stable in EMHD. We present a connection between the density-shear instability in EMHD and the magneto-buoyancy instability in anelastic MHD.
C. Noel; Y. Busegnies; M. V. Papalexandris; V. Deledicque; A. El Messoudi
2007-05-18
Aims. This work presents a new hydrodynamical algorithm to study astrophysical detonations. A prime motivation of this development is the description of a carbon detonation in conditions relevant to superbursts, which are thought to result from the propagation of a detonation front around the surface of a neutron star in the carbon layer underlying the atmosphere. Methods. The algorithm we have developed is a finite-volume method inspired by the original MUSCL scheme of van Leer (1979). The algorithm is of second-order in the smooth part of the flow and avoids dimensional splitting. It is applied to some test cases, and the time-dependent results are compared to the corresponding steady state solution. Results. Our algorithm proves to be robust to test cases, and is considered to be reliably applicable to astrophysical detonations. The preliminary one-dimensional calculations we have performed demonstrate that the carbon detonation at the surface of a neutron star is a multiscale phenomenon. The length scale of liberation of energy is $10^6$ times smaller than the total reaction length. We show that a multi-resolution approach can be used to solve all the reaction lengths. This result will be very useful in future multi-dimensional simulations. We present also thermodynamical and composition profiles after the passage of a detonation in a pure carbon or mixed carbon-iron layer, in thermodynamical conditions relevant to superbursts in pure helium accretor systems.
Development of a Hydrodynamic Model of Puget Sound and Northwest Straits
Yang, Zhaoqing; Khangaonkar, Tarang P.
2007-12-10
The hydrodynamic model used in this study is the Finite Volume Coastal Ocean Model (FVCOM) developed by the University of Massachusetts at Dartmouth. The unstructured grid and finite volume framework, as well as the capability of wetting/drying simulation and baroclinic simulation, makes FVCOM a good fit to the modeling needs for nearshore restoration in Puget Sound. The model domain covers the entire Puget Sound, Strait of Juan de Fuca, San Juan Passages, and Georgia Strait at the United States-Canada Border. The model is driven by tide, freshwater discharge, and surface wind. Preliminary model validation was conducted for tides at various locations in the straits and Puget Sound using National Oceanic and Atmospheric Administration (NOAA) tide data. The hydrodynamic model was successfully linked to the NOAA oil spill model General NOAA Operational Modeling Environment model (GNOME) to predict particle trajectories at various locations in Puget Sound. Model results demonstrated that the Puget Sound GNOME model is a useful tool to obtain first-hand information for emergency response such as oil spill and fish migration pathways.
Preparing for an explosion: Hydrodynamic instabilities and turbulence in presupernovae
Smith, Nathan; Arnett, W. David, E-mail: nathans@as.arizona.edu, E-mail: darnett@as.arizona.edu [Steward Observatory, University of Arizona, Tucson, AZ 85721 (United States)
2014-04-20
Both observations and numerical simulations are discordant with predictions of conventional stellar evolution codes for the latest stages of a massive star's life before core collapse. The most dramatic example of this disconnect is in the eruptive mass loss occurring in the decade preceding Type IIn supernovae. We outline the key empirical evidence that indicates severe pre-supernova instability in massive stars, and we suggest that the chief reason that these outbursts are absent in stellar evolution models may lie in the treatment of turbulent convection in these codes. The mixing length theory that is used ignores (1) finite amplitude fluctuations in velocity and temperature and (2) their nonlinear interaction with nuclear burning. Including these fluctuations is likely to give rise to hydrodynamic instabilities in the latest burning sequences, which prompts us to discuss a number of far-reaching implications for the fates of massive stars. In particular, we explore connections to enhanced pre-supernova mass loss, unsteady nuclear burning and consequent eruptions, swelling of the stellar radius that may trigger violent interactions with a companion star, and potential modifications to the core structure that could dramatically alter calculations of the core-collapse explosion mechanism itself. These modifications may also impact detailed nucleosynthesis and measured isotopic anomalies in meteorites, as well as the interpretation of young core-collapse supernova remnants. Understanding these critical instabilities in the final stages of evolution may make possible the development of an early warning system for impending core collapse, if we can identify their asteroseismological or eruptive signatures.
Effects of Second-Order Hydrodynamics on a Semisubmersible Floating Offshore Wind Turbine: Preprint
Bayati, I.; Jonkman, J.; Robertson, A.; Platt, A.
2014-07-01
The objective of this paper is to assess the second-order hydrodynamic effects on a semisubmersible floating offshore wind turbine. Second-order hydrodynamics induce loads and motions at the sum- and difference-frequencies of the incident waves. These effects have often been ignored in offshore wind analysis, under the assumption that they are significantly smaller than first-order effects. The sum- and difference-frequency loads can, however, excite eigenfrequencies of the system, leading to large oscillations that strain the mooring system or vibrations that cause fatigue damage to the structure. Observations of supposed second-order responses in wave-tank tests performed by the DeepCwind consortium at the MARIN offshore basin suggest that these effects might be more important than originally expected. These observations inspired interest in investigating how second-order excitation affects floating offshore wind turbines and whether second-order hydrodynamics should be included in offshore wind simulation tools like FAST in the future. In this work, the effects of second-order hydrodynamics on a floating semisubmersible offshore wind turbine are investigated. Because FAST is currently unable to account for second-order effects, a method to assess these effects was applied in which linearized properties of the floating wind system derived from FAST (including the 6x6 mass and stiffness matrices) are used by WAMIT to solve the first- and second-order hydrodynamics problems in the frequency domain. The method has been applied to the OC4-DeepCwind semisubmersible platform, supporting the NREL 5-MW baseline wind turbine. The loads and response of the system due to the second-order hydrodynamics are analysed and compared to first-order hydrodynamic loads and induced motions in the frequency domain. Further, the second-order loads and induced response data are compared to the loads and motions induced by aerodynamic loading as solved by FAST.
Cornell University Hydrodynamics | Open Energy Information
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Oregon State University Hydrodynamics | Open Energy Information
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University of Maine Hydrodynamics | Open Energy Information
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University of Michigan Hydrodynamics | Open Energy Information
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Hydrodynamic Interactions between Two Forced Objects of Arbitrary Shape: I Effect on Alignment
Tomer Goldfriend; Haim Diamant; Thomas A. Witten
2015-02-01
We study the properties and symmetries governing the hydrodynamic interaction between two identical, arbitrarily shaped objects, driven through a viscous fluid. We treat analytically the leading (dipolar) terms of the pair-mobility matrix, affecting the instantaneous relative linear and angular velocities of the two objects at large separation. We find that the ability to align asymmetric objects by an external time-dependent drive [Moths and Witten, Phys. Rev. Lett. 110, 028301 (2013)] is degraded by the hydrodynamic interaction. The effects of hydrodynamic interactions are explicitly demonstrated through numerically calculated time-dependent trajectories of model alignable objects composed of four stokeslets. In addition to the orientational effect, we find that the two objects generally repel each other, thus restoring full alignment at long times.
Jonkman, J. M.; Sclavounos, P. D.
2006-01-01
Aeroelastic simulation tools are routinely used to design and analyze onshore wind turbines, in order to obtain cost effective machines that achieve favorable performance while maintaining structural integrity. These tools employ sophisticated models of wind-inflow; aerodynamic, gravitational, and inertial loading of the rotor, nacelle, and tower; elastic effects within and between components; and mechanical actuation and electrical responses of the generator and of control and protection systems. For offshore wind turbines, additional models of the hydrodynamic loading in regular and irregular seas, the dynamic coupling between the support platform motions and wind turbine motions, and the dynamic characterization of mooring systems for compliant floating platforms are also important. Hydrodynamic loading includes contributions from hydrostatics, wave radiation, and wave scattering, including free surface memory effects. The integration of all of these models into comprehensive simulation tools, capable of modeling the fully coupled aeroelastic and hydrodynamic responses of floating offshore wind turbines, is presented.
Huijun Jiang; Zhonghuai Hou
2012-10-23
We investigate the motion of active semiflexible filament with shape kinematics and hydrodynamic interaction including. Three types of filament motion are found: Translation, snaking and rotation. Change of flexibility will induce instability of shape kinematics and further result in asymmetry of shape kinematics respect to the motion of mass center, which are responsible to a continuous-like transition from translation to snaking and a first-order-like transition from snaking to rotation, respectively. Of particular interest, we find that long-range hydrodynamic interaction is not necessary for filament rotation, but can enhance remarkably the parameter region for its appearance. This finding may provide an evidence that the experimentally found collective rotation of active filaments is more likely to arise from the individual property even without the long-range hydrodynamic interaction.
Hydrodynamics of phase transition fronts and the speed of sound in the plasma
Leonardo Leitao; Ariel Megevand
2015-03-06
The growth of bubbles in cosmological first-order phase transitions involves nontrivial hydrodynamics. For that reason, the study of the propagation of phase transition fronts often requires several approximations. A frequently used approximation consists in describing the two phases as being composed only of radiation and vacuum energy (the so-called bag equation of state). We show that, in realistic models, the speed of sound in the low-temperature phase is generally smaller than that of radiation, and we study the hydrodynamics in such a situation. We find in particular that a new kind of hydrodynamical solution may be possible, which does not arise in the bag model. We obtain analytic results for the efficiency of the transfer of latent heat to bulk motions of the plasma, as a function of the speed of sound in each phase.
Pawlik, Andreas H; Vecchia, Claudio Dalla
2015-01-01
We present a suite of cosmological radiation-hydrodynamical simulations of the assembly of galaxies driving the reionization of the intergalactic medium (IGM) at z >~ 6. The simulations account for the hydrodynamical feedback from photoionization heating and the explosion of massive stars as supernovae (SNe). Our reference simulation, which was carried out in a box of size 25 comoving Mpc/h using 2 x 512^3 particles, produces a reasonable reionization history and matches the observed UV luminosity function of galaxies. Simulations with different box sizes and resolutions are used to investigate numerical convergence, and simulations in which either SNe or photoionization heating or both are turned off, are used to investigate the role of feedback from star formation. Ionizing radiation is treated using accurate radiative transfer at the high spatially adaptive resolution at which the hydrodynamics is carried out. SN feedback strongly reduces the star formation rates (SFRs) over nearly the full mass range of s...
Transport Coefficients of Non-Newtonian Fluid and Causal Dissipative Hydrodynamics
T. Koide; T. Kodama
2008-10-20
A new formula to calculate the transport coefficients of the causal dissipative hydrodynamics is derived by using the projection operator method (Mori-Zwanzig formalism) in [T. Koide, Phys. Rev. E75, 060103(R) (2007)]. This is an extension of the Green-Kubo-Nakano (GKN) formula to the case of non-Newtonian fluids, which is the essential factor to preserve the relativistic causality in relativistic dissipative hydrodynamics. This formula is the generalization of the GKN formula in the sense that it can reproduce the GKN formula in a certain limit. In this work, we extend the previous work so as to apply to more general situations.
Statistical Estimation of Two-Body Hydrodynamic Properties Using System Identification
Xie, Chen
2010-01-14
of Liquid Natural Gas (LNG). The offloading operations from the LNG terminal to the LNG carrier are conditioned by the arm-length of LNG off-loading lines and are also somewhat constrained by the fragility of the transportation lines due to extreme low... the hydrodynamic interaction effects in both the first order motions and the mean second order drift forces on a pair of closely positioned FPSO and LNG carrier. It was shown that the simplification of using free floating single body hydrodynamics to study...
Hydrodynamic flow in lower Cretaceous Muddy sandstone, Gas Draw Field, Powder River Basin, Wyoming
Lin, Joseph Tien-Chin
1978-01-01
potentiometric gradient of 32 ft/mi across the field yields a hydrodynamic oil column of 210 ft, whereas capillary-pressure differ- ences due to permeability changes can account for only 38 ft of oil column. The observed oil column over most of the field has a... height somewhat greater than 250 ft. The agreement between total calculated oil column of about 248 ft and the observed oil column demonstrates that the positive hydrodynamic gradient across the reservoir and the decrease in permeability updip...
Centre for Marine Science and Technology: Research Report 2011-02 Aero-Hydrodynamics of an RS example for an overview of sailboard aero-hydrodynamics. The current article brings together previous
Dancing Volvox: Hydrodynamic Bound States of Swimming Algae Knut Drescher,1
Goldstein, Raymond E.
Dancing Volvox: Hydrodynamic Bound States of Swimming Algae Knut Drescher,1 Kyriacos C. Leptos,1 April 2009) The spherical alga Volvox swims by means of flagella on thousands of surface somatic cells marvels [1]. This was the freshwater alga which, years later, in the very last entry of his great work
Lauder, George V.
of hydrodynamic function, from a discrete thrust-generating propulsor acting independently from the body is currently limited by the nature of available ma- terials and mechanical drive trains. But future developments in polymer artificial muscle technology will provide a new approach to propulsor design
Purely hydrodynamic ordering of rotating disks at a finite Reynolds number
Yusuke Goto; Hajime Tanaka
2015-02-18
Self-organization of moving objects in hydrodynamic environments has recently attracted considerable attention in connection to natural phenomena and living systems. However, the underlying physical mechanism is much less clear due to the intrinsically nonequilibrium nature, compared with self-organization of thermal systems. Hydrodynamic interactions are believed to play a crucial role in such phenomena. To elucidate the fundamental physical nature of many-body hydrodynamic interactions at a finite Reynolds number, here we study a system of co-rotating hard disks in a two-dimensional viscous fluid at zero temperature. Despite the absence of thermal noise, this system exhibits rich phase behaviours, including a fluid state with diffusive dynamics, a cluster state, a hexatic state, a glassy state, a plastic crystal state and phase demixing.We reveal that these behaviours are induced by the off-axis and many-body nature of nonlinear hydrodynamic interactions and the finite time required for propagating the interactions by momentum diffusion.
Video Article A Microfluidic-based Hydrodynamic Trap for Single Particles
Schroeder, Charles
opposing laminar streams converge, thereby generating a planar extensional flow with a fluid stagnation-based technique for particle trapping and manipulation based solely on hydrodynamic fluid flow. Using this method of the flow field to maintain particle position at the fluid stagnation point. In this manner, particles
LOW MACH NUMBER MODELING OF TYPE Ia SUPERNOVAE. I. HYDRODYNAMICS A. S. Almgren,1
Bell, John B.
LOW MACH NUMBER MODELING OF TYPE Ia SUPERNOVAE. I. HYDRODYNAMICS A. S. Almgren,1 J. B. Bell,1 C. A. Rendleman,1 and M. Zingale2 Received 2005 August 5; accepted 2005 September 29 ABSTRACT We introduce a low is derived from the fully compressible equations using low Mach number asymptotics, but without any
of Newfoundland, St. John's, Newfoundland, Canada A1B 3X5 a r t i c l e i n f o Article history: Received 23 June statistical design of experiment (DOE) methodologies is proposed for a hydrodynamics experiment where there are a large number of variables. While DA is well-known, DOE is still unfamiliar to most ocean engineers
Characterizing the Hydrodynamics of Bubbling Fluidized Beds with Multivariate Pressure Measurements
Tennessee, University of
Characterizing the Hydrodynamics of Bubbling Fluidized Beds with Multivariate Pressure Measurements mounted on the walls of a bubbling fluidized bed. Our objective was to identify multivariate dynamic of bubbling fluidized beds with multivariate pressure measurements. 2000 AIChE Annual Meeting (Los Angeles
McArthur, Karl Edward
1996-01-01
The U.S. Geological Survey Surface Water Flow and Transport Model in Two-Dimensions (SV*9FT2D) model was applied to the northern half of the Laguna Madre Estuary. SW=D is a two dimensional hydrodynamic and transport model for well-mixed estuaries...
Close-Packed Floating Clusters: Granular Hydrodynamics Beyond the Freezing Point? Baruch Meerson,1
Meerson, Baruch
Close-Packed Floating Clusters: Granular Hydrodynamics Beyond the Freezing Point? Baruch Meerson,1 a simple explanation for the success of NSGH beyond the freezing point. DOI: 10.1103/PhysRevLett.91 the packing fraction approaches the freezing point value f ' 0:49 (in three dimensions) or 0.69 (in two
Hydrodynamic Conditions and Sediment Movement at Port of Port Orfordat Port of Port Orford
US Army Corps of Engineers
Hydrodynamic Conditions and Sediment Movement at Port of Port Orfordat Port of Port Orford Honghai of Engineersy p g Portland District Coastal Sediments 2015 San Diego, California May 14, 2015 US Army Corps OregonPacific g g dredging needs/costs · Define littoral sediment transport pathways that affect shoaling
A microfluidic-based hydrodynamic trap: design and implementation Melikhan Tanyeri,a
Schroeder, Charles
A microfluidic-based hydrodynamic trap: design and implementation Melikhan Tanyeri,a Mikhil Ranka: 10.1039/c0lc00709a We report an integrated microfluidic device for fine-scale manipulation in a monolithic PDMS-based microfluidic device. In this work, we characterize device design parameters enabling
Effect of Second-Order Hydrodynamics on Floating Offshore Wind Turbines: Preprint
Roald, L.; Jonkman, J.; Robertson, A,; Chokani, N.
2013-07-01
Offshore winds are generally stronger and more consistent than winds on land, making the offshore environment attractive for wind energy development. A large part of the offshore wind resource is however located in deep water, where floating turbines are the only economical way of harvesting the energy. The design of offshore floating wind turbines relies on the use of modeling tools that can simulate the entire coupled system behavior. At present, most of these tools include only first-order hydrodynamic theory. However, observations of supposed second-order hydrodynamic responses in wave-tank tests performed by the DeepCwind consortium suggest that second-order effects might be critical. In this paper, the methodology used by the oil and gas industry has been modified to apply to the analysis of floating wind turbines, and is used to assess the effect of second-order hydrodynamics on floating offshore wind turbines. The method relies on combined use of the frequency-domain tool WAMIT and the time-domain tool FAST. The proposed assessment method has been applied to two different floating wind concepts, a spar and a tension-leg-platform (TLP), both supporting the NREL 5-MW baseline wind turbine. Results showing the hydrodynamic forces and motion response for these systems are presented and analysed, and compared to aerodynamic effects.
Hydrodynamical simulations of penetrative convection and generation of internal gravity waves
Stêpieñ, Kazimierz
Hydrodynamical simulations of penetrative convection and generation of internal gravity waves M investigate the generation of internal gravity waves in the stable region below a convective layer by means of angular momentum from the place where the waves are generated to the region of their dissipation, which
XXII ICTAM, 2529 August 2008, Adelaide, Australia PERISTALSIS AND HYDRODYNAMIC INSTABILITIES
Hoepffner, Jérôme
-Ku, Yokohama 223-8522, Japan. Summary Peristaltic pumping is considered in view of early nonlinear mechanisms in hydrodynamic instabilities. A propagating wall deformation generates pressure gradients in the flow, which act a progressive wave of area contraction or expansion propagates along the length of a distensible tube containing
Fischer, Paul F.
-averaged Navier- Stokes) and subchannel models. Our initial study is focused on LES of sodium-cooled fast reactorPetascale Algorithms for Reactor Hydrodynamics Paul Fischer, James Lottes, David Pointer, and Andew describe recent algorithmic developments that have enabled large eddy simulations of reactor flows on up
Basic design and hydrodynamic analysis of three-column TLP and comparison with ISSC TLP
Sebastian, Abhilash
2000-01-01
Three-column TLP is a new design variation of the common four-column TLP. The objective of this study is to find the hydrodynamic feasibility of the three-column TLP. This accomplished by comparing the three-column design to the ISSC TLP. The ISSC...
Vlasov equation and collisionless hydrodynamics adapted to curved I. Y. Dodin and N. J. Fisch
Vlasov equation and collisionless hydrodynamics adapted to curved spacetime I. Y. Dodin and N. J of the Vlasov equation, in its standard form describing a charged particle distribution in the six. The equation accounts simultaneously for the Lorentz force and the effects of general relativity
Hydrodynamic and Structural Performance of the Transverse Horizontal Axis Water Turbine
Gorban, Alexander N.
of Darrieus vertical axis wind turbine (VAWT) through 90 to lie horizontally across a tidal flow · Stretch power (2) · Vertical axis turbines Blue Energy Polo ... 4 other vertical axis devices · HorizontalHydrodynamic and Structural Performance of the Transverse Horizontal Axis Water Turbine Prof. Guy
ASPECTS OF SENSORY CUES AND PROPULSION IN MARINE ZOOPLANKTON HYDRODYNAMIC DISTURBANCES
colleagues (Environmental Fluid Mechanics and Biology graduate students) for their input and adviceASPECTS OF SENSORY CUES AND PROPULSION IN MARINE ZOOPLANKTON HYDRODYNAMIC DISTURBANCES A Thesis Institute of Technology December 2009 #12;ASPECTS OF SENSORY CUES AND PROPULSION IN MARINE ZOOPLANKTON
One dimensional electromagnetic relativistic PIC-hydrodynamic hybrid simulation code H-VLPL
Grimm, Volker
One dimensional electromagnetic relativistic PIC-hydrodynamic hybrid simulation code H-VLPL (Hybrid full electromagnetic relativistic hybrid plasma model. The full kinetic particle-in cell (PIC, there is a demand to simulate high density plasmas, e.g., in the experiments where the laser pulse interacts
Influence of increased gas density on hydrodynamics of bubble-column reactors
Krishna, R.; Swart, J.W.A. de; Hennephof, D.E.; Ellenberger, J.; Hoefsloot, H.C.J. (Univ. of Amsterdam (Netherlands). Dept. of Chemical Engineering)
1994-01-01
A mechanistic background to the understanding of the hydrodynamics of high-pressure bubble column reactors in both the homogeneous and heterogeneous flow regimes is discussed. An important parameter determining the stability of homogeneous bubbly flow in a bubble column is shown to be the Richardson-Zaki exponent in the bubble swarm velocity relationship V[sub swarm] = [upsilon][sub [infinity
Coiling, Entrainment, and Hydrodynamic Coupling of Decelerated Fluid Jets Christopher Dombrowski,1
Goldstein, Raymond E.
Coiling, Entrainment, and Hydrodynamic Coupling of Decelerated Fluid Jets Christopher Dombrowski,1 suspensions to magma upwellings, one finds jets which exhibit complex symmetry-breaking instabilities as they are decelerated by their surroundings. We consider here a model system--a saline jet descending through a salinity
CE-QUAL-W2 Version 3: Hydrodynamic and Water Quality River Basin Modeling
Wells, Scott A.
and Oregon; the Bull Run River basin composed of 3 water sup- ply reservoirs and 2 river sections with a 2CE-QUAL-W2 Version 3: Hydrodynamic and Water Quality River Basin Modeling S. A. Wells Department for deep, long, and narrow waterbodies. The current model, Version 2, has been used in over 200 river
Hydrodynamic and water quality river basin modeling using CE-QUAL-W2 version 3
Wells, Scott A.
of the Lower Snake River in the Northwestern USA; the Bull Run River basin composed of 3 water supplyHydrodynamic and water quality river basin modeling using CE-QUAL-W2 version 3 Scott A. Wells for deep, long, and narrow waterbodies. The current model, Version 2, has been used in over 200 river
Recent Hydrodynamics Improvements to the RELAP5-3D Code
Richard A. Riemke; Cliff B. Davis; Richard.R. Schultz
2009-07-01
The hydrodynamics section of the RELAP5-3D computer program has been recently improved. Changes were made as follows: (1) improved turbine model, (2) spray model for the pressurizer model, (3) feedwater heater model, (4) radiological transport model, (5) improved pump model, and (6) compressor model.
A Phase Field Crystal Model for Colloidal Suspensions with Hydrodynamic Interactions
Praetorius, Simon
2013-01-01
We develop a fully continuous model for colloidal suspensions with hydrodynamic interactions. The Navier Stokes Phase Field Crystal (NS-PFC) model combines ideas of dynamic density functional theory with particulate flow approaches. The proposed dynamical equations are shown to be energy stable. The system is numerically solved using adaptive finite elements. The resulting approach is validated against computational and experimental studies for sedimentation.
The Segmented Height Field and Smoothed Particle Hydrodynamics in Erosion Simulation
Franklin, W. Randolph
Katrina and has been replaced with a cement retaining wall. #12;Terms Erosion - refers to hydraulic erosion, or the physical wearing away or breaking down of a material by running water Earthen dams - walls., Hydraulic Erosion Using Smoothed Particle Hydrodynamics, 2009. #12;Why Use SPH? Not hindered by grid
Volumetric imaging of shark tail hydrodynamics reveals a three-dimensional
Lauder, George V.
Volumetric imaging of shark tail hydrodynamics reveals a three-dimensional dual-ring vortex wake-dimensional, volumetric imaging technique that allows instantaneous capture of wake flow patterns, to a classic problem analyses, and show that the volumetric approach reveals a different vortex wake not previously
A hydrodynamic theory for solutions of nonhomogeneous nematic liquid crystalline polymers of
A hydrodynamic theory for solutions of nonhomogeneous nematic liquid crystalline polymers of di#11 polymers (LCPs) of a variety of molecular con#12;gurations in proximity of spheroids, extending the Doi to be applicable to high molar weight liquid crystalline polymers. Although the LE theory was #12;rst developed
1. Department, course number, title ORE 609 Hydrodynamics of Fluid-Body Interaction
on Offshore Structures 2. Newman: Marine Hydrodynamics 3. Currie: Fundamental Mechanics of Fluids 4. Ippen and Stegun: Handbook of Mathematical Functions 7. Gradshteyn and Ryzhik: Table of Integrals, Series Component Engineering science: 2 credits Engineering design: 1 credit 10. Relationship of the Course
A Godunov-like point-centered essentially Lagrangian hydrodynamic approach
Morgan, Nathaniel R.; Waltz, Jacob I.; Burton, Donald E.; Charest, Marc R.; Canfield, Thomas R.; Wohlbier, John G.
2014-10-28
We present an essentially Lagrangian hydrodynamic scheme suitable for modeling complex compressible flows on tetrahedron meshes. The scheme reduces to a purely Lagrangian approach when the flow is linear or if the mesh size is equal to zero; as a result, we use the term essentially Lagrangian for the proposed approach. The motivation for developing a hydrodynamic method for tetrahedron meshes is because tetrahedron meshes have some advantages over other mesh topologies. Notable advantages include reduced complexity in generating conformal meshes, reduced complexity in mesh reconnection, and preserving tetrahedron cells with automatic mesh refinement. A challenge, however, is tetrahedron meshes do not correctly deform with a lower order (i.e. piecewise constant) staggered-grid hydrodynamic scheme (SGH) or with a cell-centered hydrodynamic (CCH) scheme. The SGH and CCH approaches calculate the strain via the tetrahedron, which can cause artificial stiffness on large deformation problems. To resolve the stiffness problem, we adopt the point-centered hydrodynamic approach (PCH) and calculate the evolution of the flow via an integration path around the node. The PCH approach stores the conserved variables (mass, momentum, and total energy) at the node. The evolution equations for momentum and total energy are discretized using an edge-based finite element (FE) approach with linear basis functions. A multidirectional Riemann-like problem is introduced at the center of the tetrahedron to account for discontinuities in the flow such as a shock. Conservation is enforced at each tetrahedron center. The multidimensional Riemann-like problem used here is based on Lagrangian CCH work [8, 19, 37, 38, 44] and recent Lagrangian SGH work [33-35, 39, 45]. In addition, an approximate 1D Riemann problem is solved on each face of the nodal control volume to advect mass, momentum, and total energy. The 1D Riemann problem produces fluxes [18] that remove a volume error in the PCH discretization. A 2-stage Runge–Kutta method is used to evolve the solution in time. The details of the new hydrodynamic scheme are discussed; likewise, results from numerical test problems are presented.
A Godunov-like point-centered essentially Lagrangian hydrodynamic approach
DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)
Morgan, Nathaniel R.; Waltz, Jacob I.; Burton, Donald E.; Charest, Marc R.; Canfield, Thomas R.; Wohlbier, John G.
2014-10-28
We present an essentially Lagrangian hydrodynamic scheme suitable for modeling complex compressible flows on tetrahedron meshes. The scheme reduces to a purely Lagrangian approach when the flow is linear or if the mesh size is equal to zero; as a result, we use the term essentially Lagrangian for the proposed approach. The motivation for developing a hydrodynamic method for tetrahedron meshes is because tetrahedron meshes have some advantages over other mesh topologies. Notable advantages include reduced complexity in generating conformal meshes, reduced complexity in mesh reconnection, and preserving tetrahedron cells with automatic mesh refinement. A challenge, however, is tetrahedron meshesmore »do not correctly deform with a lower order (i.e. piecewise constant) staggered-grid hydrodynamic scheme (SGH) or with a cell-centered hydrodynamic (CCH) scheme. The SGH and CCH approaches calculate the strain via the tetrahedron, which can cause artificial stiffness on large deformation problems. To resolve the stiffness problem, we adopt the point-centered hydrodynamic approach (PCH) and calculate the evolution of the flow via an integration path around the node. The PCH approach stores the conserved variables (mass, momentum, and total energy) at the node. The evolution equations for momentum and total energy are discretized using an edge-based finite element (FE) approach with linear basis functions. A multidirectional Riemann-like problem is introduced at the center of the tetrahedron to account for discontinuities in the flow such as a shock. Conservation is enforced at each tetrahedron center. The multidimensional Riemann-like problem used here is based on Lagrangian CCH work [8, 19, 37, 38, 44] and recent Lagrangian SGH work [33-35, 39, 45]. In addition, an approximate 1D Riemann problem is solved on each face of the nodal control volume to advect mass, momentum, and total energy. The 1D Riemann problem produces fluxes [18] that remove a volume error in the PCH discretization. A 2-stage Runge–Kutta method is used to evolve the solution in time. The details of the new hydrodynamic scheme are discussed; likewise, results from numerical test problems are presented.« less
Solving 3D relativistic hydrodynamical problems with WENO discontinuous Galerkin methods
Bugner, Marcus; Bernuzzi, Sebastiano; Weyhausen, Andreas; Bruegmann, Bernd
2015-01-01
Discontinuous Galerkin (DG) methods coupled to WENO algorithms allow high order convergence for smooth problems and for the simulation of discontinuities and shocks. In this work, we investigate WENO-DG algorithms in the context of numerical general relativity, in particular for general relativistic hydrodynamics. We implement the standard WENO method at different orders, a compact (simple) WENO scheme, as well as an alternative subcell evolution algorithm. To evaluate the performance of the different numerical schemes, we study non-relativistic, special relativistic, and general relativistic testbeds. We present the first three-dimensional simulations of general relativistic hydrodynamics, albeit for a fixed spacetime background, within the framework of WENO-DG methods. The most important testbed is a single TOV-star in three dimensions, showing that long term stable simulations of single isolated neutron stars can be obtained with WENO-DG methods.
Energy flow between two hydrodynamically coupled particles kept at different effective temperatures
Antoine Bérut; Artyom Petrosyan; Sergio Ciliberto
2015-05-26
We measure the energy exchanged between two hydrodynamically coupled micron-sized Brownian particles trapped in water by two optical tweezers. The system is driven out of equilibrium by random forcing the position of one of the two particles. The forced particle behaves as it has an "effective temperature" higher than that of the other bead. This driving modifies the equilibrium variances and cross-correlation functions of the bead positions: we measure an energy flow between the particles and an instantaneous cross-correlation, proportional to the effective temperature difference between the two particles. A model of the interaction which is based on classical hydrodynamic coupling tensors is proposed. The theoretical and experimental results are in excellent agreement.
Murphy, Jeremiah W
2008-01-01
In this paper, we describe a new hydrodynamics code for 1D and 2D astrophysical simulations, BETHE-hydro, that uses time-dependent, arbitrary, unstructured grids. The core of the hydrodynamics algorithm is an arbitrary Lagrangian-Eulerian (ALE) approach, in which the gradient and divergence operators are made compatible using the support-operator method. We present 1D and 2D gravity solvers that are finite differenced using the support-operator technique, and the resulting system of linear equations are solved using the tridiagonal method for 1D simulations and an iterative multigrid-preconditioned conjugate-gradient method for 2D simulations. Rotational terms are included for 2D calculations using cylindrical coordinates. We document an incompatibility between a subcell pressure algorithm to suppress hourglass motions and the subcell remapping algorithm and present a modified subcell pressure scheme that avoids this problem. Strengths of this code include a straightforward structure, enabling simple inclusio...
The Kozai-Lidov Mechanism in Hydrodynamical Disks - II. Effects of binary and disk parameters
Fu, Wen; Martin, Rebecca G
2015-01-01
Martin et al. (2014b) showed that a substantially misaligned accretion disk around one component of a binary system can undergo global damped Kozai-Lidov oscillations. During these oscillations, the inclination and eccentricity of the disk are periodically exchanged. However, the robustness of this mechanism and its dependence on the system parameters were unexplored. In this paper, we use three-dimensional hydrodynamical simulations to analyze how various binary and disk parameters affect the Kozai-Lidov mechanism in hydrodynamical disks. The simulations include the effect of gas pressure and viscosity, but ignore the effects of disk self-gravity. We describe results for different numerical resolutions, binary mass ratios and orbital eccentricities, initial disk sizes, initial disk surface density profiles, disk sound speeds, and disk viscosities. We show that the Kozai-Lidov mechanism can operate for a wide range of binary-disk parameters. We discuss the applications of our results to astrophysical disks in...
Low torque hydrodynamic lip geometry for bi-directional rotation seals
Dietle, Lannie L. (Houston, TX); Schroeder, John E. (Richmond, TX)
2011-11-15
A hydrodynamically lubricating geometry for the generally circular dynamic sealing lip of rotary seals that are employed to partition a lubricant from an environment. The dynamic sealing lip is provided for establishing compressed sealing engagement with a relatively rotatable surface, and for wedging a film of lubricating fluid into the interface between the dynamic sealing lip and the relatively rotatable surface in response to relative rotation that may occur in the clockwise or the counter-clockwise direction. A wave form incorporating an elongated dimple provides the gradual convergence, efficient impingement angle, and gradual interfacial contact pressure rise that are conducive to efficient hydrodynamic wedging. Skewed elevated contact pressure zones produced by compression edge effects provide for controlled lubricant movement within the dynamic sealing interface between the seal and the relatively rotatable surface, producing enhanced lubrication and low running torque.
Low torque hydrodynamic lip geometry for bi-directional rotation seals
Dietle, Lannie L. (Houston, TX); Schroeder, John E. (Richmond, TX)
2009-07-21
A hydrodynamically lubricating geometry for the generally circular dynamic sealing lip of rotary seals that are employed to partition a lubricant from an environment. The dynamic sealing lip is provided for establishing compressed sealing engagement with a relatively rotatable surface, and for wedging a film of lubricating fluid into the interface between the dynamic sealing lip and the relatively rotatable surface in response to relative rotation that may occur in the clockwise or the counter-clockwise direction. A wave form incorporating an elongated dimple provides the gradual convergence, efficient impingement angle, and gradual interfacial contact pressure rise that are conducive to efficient hydrodynamic wedging. Skewed elevated contact pressure zones produced by compression edge effects provide for controlled lubricant movement within the dynamic sealing interface between the seal and the relatively rotatable surface, producing enhanced lubrication and low running torque.
GPU-accelerated simulation of colloidal suspensions with direct hydrodynamic interactions
Kopp, Michael
2012-01-01
Solvent-mediated hydrodynamic interactions between colloidal particles can significantly alter their dynamics. We discuss the implementation of Stokesian dynamics in leading approximation for streaming processors as provided by the compute unified device architecture (CUDA) of recent graphics processors (GPUs). Thereby, the simulation of explicit solvent particles is avoided and hydrodynamic interactions can easily be accounted for in already available, highly accelerated molecular dynamics simulations. Special emphasis is put on efficient memory access and numerical stability. The algorithm is applied to the periodic sedimentation of a cluster of four suspended particles. Finally, we investigate the runtime performance of generic memory access patterns of complexity $O(N^2)$ for various GPU algorithms relying on either hardware cache or shared memory.
The Kozai-Lidov mechanism in hydrodynamical disks. II. Effects of binary and disk parameters
DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)
Fu, Wen; Lubow, Stephen H.; Martin, Rebecca G.
2015-07-01
Martin et al. (2014b) showed that a substantially misaligned accretion disk around one component of a binary system can undergo global damped Kozai–Lidov (KL) oscillations. During these oscillations, the inclination and eccentricity of the disk are periodically exchanged. However, the robustness of this mechanism and its dependence on the system parameters were unexplored. In this paper, we use three-dimensional hydrodynamical simulations to analyze how various binary and disk parameters affect the KL mechanism in hydrodynamical disks. The simulations include the effect of gas pressure and viscosity, but ignore the effects of disk self-gravity. We describe results for different numerical resolutions,more »binary mass ratios and orbital eccentricities, initial disk sizes, initial disk surface density profiles, disk sound speeds, and disk viscosities. We show that the KL mechanism can operate for a wide range of binary-disk parameters. We discuss the applications of our results to astrophysical disks in various accreting systems.« less
Schaal, Kevin; Chandrashekar, Praveen; Pakmor, Rüdiger; Klingenberg, Christian; Springel, Volker
2015-01-01
Solving the Euler equations of ideal hydrodynamics as accurately and efficiently as possible is a key requirement in many astrophysical simulations. It is therefore important to continuously advance the numerical methods implemented in current astrophysical codes, especially also in light of evolving computer technology, which favours certain computational approaches over others. Here we introduce the new adaptive mesh refinement (AMR) code TENET, which employs a high-order Discontinuous Galerkin (DG) scheme for hydrodynamics. The Euler equations in this method are solved in a weak formulation with a polynomial basis by means of explicit Runge-Kutta time integration and Gauss-Legendre quadrature. This approach offers significant advantages over commonly employed finite volume (FV) solvers. In particular, the higher order capability renders it computationally more efficient, in the sense that the same precision can be obtained at significantly less computational cost. Also, the DG scheme inherently conserves a...
Swaddiwudhipong, S; Liu, Z S
2012-01-01
Finite element method (FEM) suffers from a serious mesh distortion problem when used for high velocity impact analyses. The smooth particle hydrodynamics (SPH) method is appropriate for this class of problems involving severe damages but at considerable computational cost. It is beneficial if the latter is adopted only in severely distorted regions and FEM further away. The coupled smooth particle hydrodynamics - finite element method (SFM) has been adopted in a commercial hydrocode LS-DYNA to study the perforation of Weldox 460E steel and AA5083-H116 aluminum plates with varying thicknesses and various projectile nose geometries including blunt, conical and ogival noses. Effects of the SPH domain size and particle density are studied considering the friction effect between the projectile and the target materials. The simulated residual velocities and the ballistic limit velocities from the SFM agree well with the published experimental data. The study shows that SFM is able to emulate the same failure mechan...
Rominger, Jeffrey T. (Jeffrey Tsaros)
2014-01-01
From the canopy scale to the blade scale, interactions between fluid motion and kelp produce a wide array of hydrodynamic and scalar transport phenomena. At the kilometer scale of the kelp forest, coastal currents transport ...
Paul, Ephraim Udo
2011-02-22
This study was conducted to ascertain the impacts of bed leveling, following ship channel dredging operations, and to also investigate the hydrodynamic flow field around box bed levelers. Laboratory experiments were conducted with bed levelers...
Mosher, Phillip Andrew
1993-01-01
Hybrid (combination hydrostatic and hydrodynamic) bearings have been proposed for use as a support element in cryogenic high speed turbomachinery for primary and auxiliary space power applications because of their long lifetime, low friction...
Alexeev, Boris V
2008-01-01
Quantum solitons are discovered with the help of generalized quantum hydrodynamics (GQH). The solitons have the character of the stable quantum objects in the self consistent electric field. These effects can be considered as explanation of the existence of lightning balls. The delivered theory demonstrates the great possibilities of the generalized quantum hydrodynamics in investigation of the quantum solitons. The paper can be considered also as comments and prolongation of the materials published in the known author`s monograph (Boris V. Alexeev, Generalized Boltzmann Physical Kinetics. Elsevier. 2004). The theory leads to solitons as typical formations in the generalized quantum hydrodynamics. Key words: Foundations of the theory of transport processes; The theory of solitons; Generalized hydrodynamic equations; Foundations of quantum mechanics; The theory of lightning balls. PACS: 67.55.Fa, 67.55.Hc
A Newton-Krylov Solver for Implicit Solution of Hydrodynamics in Core Collapse Supernovae
Reynolds, D R; Swesty, F D; Woodward, C S
2008-06-12
This paper describes an implicit approach and nonlinear solver for solution of radiation-hydrodynamic problems in the context of supernovae and proto-neutron star cooling. The robust approach applies Newton-Krylov methods and overcomes the difficulties of discontinuous limiters in the discretized equations and scaling of the equations over wide ranges of physical behavior. We discuss these difficulties, our approach for overcoming them, and numerical results demonstrating accuracy and efficiency of the method.
Starrfield, S.; Kenyon, S.; Truran, J.W.; Sparks, W.M.
1983-01-01
We have used a Lagrangian, hydrodynamic stellar-evolution computer code to evolve a thermonuclear runaway in the accreted hydrogen rich envelope of a 1.0M, 10-km neutron star. Our simulation produced an outburst which lasted about 2000 sec and peak effective temperature was 3 keV. The peak luminosity exceeded 2 x 10/sup 5/ L. A shock wave caused a precursor in the light curve which lasted 10/sup -5/ sec.
Simulation study of the effect of hydrodynamic forces on oil recovery
Idrobo Hurtado, Eduardo Alejandro
1992-01-01
of entrapment was also investigated. DEDICATION To my wife Angela Maria and my daughter Maria Angelica for their undying love, support, and patience. To my parents: Eduardo Idrobo Mazorra y Maruja Hurtado de Idmbo. ACKNOWLEDGEMENTS I would like to thank... Transmissibility of 0. 2 md-d/stb 52 52 Hydrodynamic Case when a Fault is Present. . . . . . . . . . . 53 CHAPTER V ? SUMMARY AND CONCLUSIONS . Summary. Conclusions NOMENCLATURE REFERENCES . VITA Page 61 . . . 61 . . 62 65 67 69 LIST OF TABLES...
General relativistic radiation hydrodynamics of accretion flows. I: Bondi-Hoyle accretion
Olindo Zanotti; Constanze Roedig; Luciano Rezzolla; Luca Del Zanna
2015-03-10
We present a new code for performing general-relativistic radiation-hydrodynamics simulations of accretion flows onto black holes. The radiation field is treated in the optically-thick approximation, with the opacity contributed by Thomson scattering and thermal bremsstrahlung. Our analysis is concentrated on a detailed numerical investigation of hot two-dimensional, Bondi-Hoyle accretion flows with various Mach numbers. We find significant differences with respect to purely hydrodynamical evolutions. In particular, once the system relaxes to a radiation-pressure dominated regime, the accretion rates become about two orders of magnitude smaller than in the purely hydrodynamical case, remaining however super-Eddington as are the luminosities. Furthermore, when increasing the Mach number of the inflowing gas, the accretion rates become smaller because of the smaller cross section of the black hole, but the luminosities increase as a result a stronger emission in the shocked regions. Overall, our approach provides the first self-consistent calculation of the Bondi-Hoyle luminosity, most of which is emitted within r~100 M from the black hole, with typical values L/L_Edd ~ 1-7, and corresponding energy efficiencies eta_BH ~ 0.09-0.5. The possibility of computing luminosities self-consistently has also allowed us to compare with the bremsstrahlung luminosity often used in modelling the electromagnetic counterparts to supermassive black-hole binaries, to find that in the optically-thick regime these more crude estimates are about 20 times larger than our radiation-hydrodynamics results.
Gidaspow, D.
1996-04-01
The objective of this investigation is to convert our ``learning gas solid-liquid`` fluidization model into a predictive design model. The IIT hydrodynamic model computes the phase velocities and the volume fractions of gas, liquid and particulate phase. Model verification involves a comparison of these computed velocities and volume fractions to experimental values. A hydrodynamic model for multiphase flows, based on the principles of mass, momentum and energy conservation for each phase, was developed and applied to model gas-liquid, gas-liquid-solid fluidization and gas-solid-solid separation. To simulate the industrial slurry bubble column reactors, a computer program based on the hydrodynamic model was written with modules for chemical reactions (e.g. the synthesis of methanol), phase changes and heat exchangers. In the simulations of gas-liquid two phases flow system, the gas hold-ups, computed with a variety of operating conditions such as temperature, pressure, gas and liquid velocities, agree well with the measurements obtained at Air Products` pilot plant. The hydrodynamic model has more flexible features than the previous empirical correlations in predicting the gas hold-up of gas-liquid two-phase flow systems. In the simulations of gas-liquid-solid bubble column reactors with and without slurry circulation, the code computes volume fractions, temperatures and velocity distributions for the gas, the liquid and the solid phases, as well as concentration distributions for the species (CO, H{sub 2}, CH{sub 3}0H, ... ), after startup from a certain initial state. A kinetic theory approach is used to compute a solid viscosity due to particle collisions. Solid motion and gas-liquid-solid mixing are observed on a color PCSHOW movie made from computed time series data. The steady state and time average catalyst concentration profiles, the slurry height and the rates of methanol production agree well with the measurements obtained at an Air Products` pilot plant.
Dynamic Forces between Bubbles and Surfaces and Hydrodynamic Boundary Conditions
Chan, Derek Y C
of Mathematics, National UniVersity of Singapore, 117543 Singapore, Institute of High Performance Computing, 1 of High Performance Computing. | Institute of Chemical and Engineering Sciences. (1) Whitesides, G. M
DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)
Doss, F. W.; Kline, J. L.; Flippo, K. A.; Perry, T. S.; DeVolder, B. G.; Tregillis, I.; Loomis, E. N.; Merritt, E. C.; Murphy, T. J.; Welser-Sherrill, L.; et al
2015-04-17
An indirectly-driven shock tube experiment fielded on the National Ignition Facility (NIF) was used to create a high-energy-density hydrodynamics platform at unprecedented scale. Scaling up a shear-induced mixing experiment previously fielded at OMEGA, the NIF shear platform drives 130 ?m/ns shocks into a CH foam-filled shock tube (~ 60 mg/cc) with interior dimensions of 1.5 mm diameter and 5 mm length. The pulse-shaping capabilities of the NIF are used to extend the drive for >10 ns, and the large interior tube volumes are used to isolate physics-altering edge effects from the region of interest. The scaling of the experiment tomore »the NIF allows for considerable improvement in maximum driving time of hydrodynamics, in fidelity of physics under examination, and in diagnostic clarity. Details of the experimental platform and post-shot simulations used in the analysis of the platform-qualifying data are presented. Hydrodynamic scaling is used to compare shear data from OMEGA with that from NIF, suggesting a possible change in the dimensionality of the instability at late times from one platform to the other.« less
3D hydrodynamical and radiative transfer modeling of Eta Carinae's colliding winds
Madura, Thomas I; Gull, Theodore R; Kruip, Chael J H; Paardekooper, Jan-Pieter; Icke, Vincent
2015-01-01
We present results of full 3D hydrodynamical and radiative transfer simulations of the colliding stellar winds in the massive binary system Eta Carinae. We accomplish this by applying the SimpleX algorithm for 3D radiative transfer on an unstructured Voronoi-Delaunay grid to recent 3D smoothed particle hydrodynamics (SPH) simulations of the binary colliding winds. We use SimpleX to obtain detailed ionization fractions of hydrogen and helium, in 3D, at the resolution of the original SPH simulations. We investigate several computational domain sizes and Luminous Blue Variable primary star mass-loss rates. We furthermore present new methods of visualizing and interacting with output from complex 3D numerical simulations, including 3D interactive graphics and 3D printing. While we initially focus on Eta Car, the methods employed can be applied to numerous other colliding wind (WR 140, WR 137, WR 19) and dusty 'pinwheel' (WR 104, WR 98a) binary systems. Coupled with 3D hydrodynamical simulations, SimpleX simulatio...
Hydrodynamical study of neutrino-driven wind as an r-process site
K. Sumiyoshi; H. Suzuki; K. Otsuki; M. Terasawa; S. Yamada
1999-12-08
We study the neutrino-driven wind from the proto-neutron star by the general relativistic hydrodynamical simulations. We examine the properties of the neutrino-driven wind to explore the possibility of the r-process nucleosynthesis. The numerical simulations with the neutrino heating and cooling processes are performed with the assumption of the constant neutrino luminosity by using realistic profiles of the proto-neutron star (PNS) as well as simplified models. The dependence on the mass of PNS and the neutrino luminosity is studied systematically. Comparisons with the analytic treatment in the previous studies are also done. In the cases with the realistic PNS, we found that the entropy per baryon and the expansion time scale are neither high nor short enough for the r-process within the current assumptions. On the other hand, we found that the expansion time scale obtained by the hydrodynamical simulations is systematically shorter than that in the analytic solutions due to our proper treatment of the equation of state. This fact might lead to the increase of the neutron-to-seed ratio, which is suitable for the r-process in the neutrino-driven wind. Indeed, in the case of massive and compact proto-neutron stars with high neutrino luminosities, the expansion time scale is found short enough in the hydrodynamical simulations and the r-process elements up to A ~ 200 are produced in the r-process network calculation.
A point-centered arbitrary Lagrangian Eulerian hydrodynamic approach for tetrahedral meshes
DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)
Morgan, Nathaniel R.; Waltz, Jacob I.; Burton, Donald E.; Charest, Marc R.; Canfield, Thomas R.; Wohlbier, John G.
2015-02-24
We present a three dimensional (3D) arbitrary Lagrangian Eulerian (ALE) hydrodynamic scheme suitable for modeling complex compressible flows on tetrahedral meshes. The new approach stores the conserved variables (mass, momentum, and total energy) at the nodes of the mesh and solves the conservation equations on a control volume surrounding the point. This type of an approach is termed a point-centered hydrodynamic (PCH) method. The conservation equations are discretized using an edge-based finite element (FE) approach with linear basis functions. All fluxes in the new approach are calculated at the center of each tetrahedron. A multidirectional Riemann-like problem is solved atmore »the center of the tetrahedron. The advective fluxes are calculated by solving a 1D Riemann problem on each face of the nodal control volume. A 2-stage Runge–Kutta method is used to evolve the solution forward in time, where the advective fluxes are part of the temporal integration. The mesh velocity is smoothed by solving a Laplacian equation. The details of the new ALE hydrodynamic scheme are discussed. Results from a range of numerical test problems are presented.« less
Experimental and computational studies of hydrodynamics in three-phase and two-phase fluidized beds
Bahary, M.
1994-12-01
The objective of the present study was to investigate the hydrodynamics of three-phase fluidized beds, their rheology, and experimentally verify a predictive three fluid hydrodynamic model developed at the Illinois Institute of Technology, Chicago. The recent reviews show that there exist no such models in the literature. The IIT hydrodynamic model computes the phase velocities and the volume fractions of gas, liquid, and particulate phases. Model verification involves a comparison of these computed velocities and volume fractions to experimental values. In this thesis, a three fluid model is presented. The input into the model can be particulate viscosities either measured with a Brookfield viscometer or derived using the mathematical techniques of kinetic theory of granular flows pioneered by Savage and others. The computer simulation of a three-phase fluidized bed in an asymmetric mode qualitatively predicts the gas, liquid and solid hold-ups (volume fractions) and flow patterns in the industrially important churn-turbulent (bubbly coalesced) regimes. The computations in a fluidized bed with a symmetric distributor incorrectly showed no bubble coalescence. A combination of X-ray and {gamma}-ray densitometers was used to measure the solids and the liquid volume fractions in a two dimensional bed in the bubble coalesced regime. There is a good agreement between the theory for an asymmetric distributor and the experiments.
V. Yu. Naboka; S. V. Akkelin; Iu. A. Karpenko; Yu. M. Sinyukov
2015-01-14
A key ingredient of hydrodynamical modeling of relativistic heavy ion collisions is thermal initial conditions, an input that is the consequence of a pre-thermal dynamics which is not completely understood yet. In the paper we employ a recently developed energy-momentum transport model of the pre-thermal stage to study influence of the alternative initial states in nucleus-nucleus collisions on flow and energy density distributions of the matter at the starting time of hydrodynamics. In particular, the dependence of the results on isotropic and anisotropic initial states is analyzed. It is found that at the thermalization time the transverse flow is larger and the maximal energy density is higher for the longitudinally squeezed initial momentum distributions. The results are also sensitive to the relaxation time parameter, equation of state at the thermalization time, and transverse profile of initial energy density distribution: Gaussian approximation, Glauber Monte Carlo profiles, etc. Also, test results ensure that the numerical code based on the energy-momentum transport model is capable of providing both averaged and fluctuating initial conditions for the hydrodynamic simulations of relativistic nuclear collisions.
Jeremiah W. Murphy; Adam Burrows
2008-07-09
In this paper, we describe a new hydrodynamics code for 1D and 2D astrophysical simulations, BETHE-hydro, that uses time-dependent, arbitrary, unstructured grids. The core of the hydrodynamics algorithm is an arbitrary Lagrangian-Eulerian (ALE) approach, in which the gradient and divergence operators are made compatible using the support-operator method. We present 1D and 2D gravity solvers that are finite differenced using the support-operator technique, and the resulting system of linear equations are solved using the tridiagonal method for 1D simulations and an iterative multigrid-preconditioned conjugate-gradient method for 2D simulations. Rotational terms are included for 2D calculations using cylindrical coordinates. We document an incompatibility between a subcell pressure algorithm to suppress hourglass motions and the subcell remapping algorithm and present a modified subcell pressure scheme that avoids this problem. Strengths of this code include a straightforward structure, enabling simple inclusion of additional physics packages, the ability to use a general equation of state, and most importantly, the ability to solve self-gravitating hydrodynamic flows on time-dependent, arbitrary grids. In what follows, we describe in detail the numerical techniques employed and, with a large suite of tests, demonstrate that BETHE-hydro finds accurate solutions with 2$^{nd}$-order convergence.
Chiho Nonaka; Eiji Honda; Shin Muroya
2000-07-19
A full (3+1)-dimensional calculation using the Lagrangian hydrodynamics is proposed for relativistic nuclear collisions. The calculation enables us to evaluate anisotropic flow of hadronic matter which appears in non-central and/or asymmetrical relativistic nuclear collisions. Applying hydrodynamical calculations to the deformed uranium collisions at AGS energy region, we discuss the nature of space-time structure and particle distributions in detail.
Linn, Anne Marie
1985-01-01
DEPOSITIONAL ENVIRONMENT AND HYDRODYNAMIC FLOW IN GUADALUPIAN CHERRY CANYON SANDSTONE, WEST FORD AND WEST GERALDINE FIELDS, DELAWARE BASIN, TEXAS A Thesis by Anne Marie Linn Submitted to the Graduate College of Texas ARM Univer sity... in partial fulfillment of the requirement for the degree of MASTER OF SCIENCE August 1985 Major Sub)cot: Geology DEPOSITIONAL ENVIRONMENT AND HYDRODYNAMIC FLOW IN GUADALUPIAN CHERRY CANYON SANDSTONE, WEST FORD AND WEST GERALDINE FIELDS, DELAWARE BASIN...
Web-Based Hydrodynamics Computing Alan Shimoide1
Yoon, Ilmi
University Abstract Proteins are long chains of amino acids that have a definite 3-d conformation through a web browser. 1. Introduction Proteins are long chains of amino acids that have a definite conformation in three dimensions after the chain of amino acids has been folded in a specific fashion. Proteins
Hydrodynamic and numerical modeling of a spherical homogeneous.pdf
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AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Homesum_a_epg0_fpd_mmcf_m.xls" ,"Available from WebQuantityBonneville Power Administration would likeUniverse (JournalvivoHighHussein Khalil Hussein KhalilStatistical Self-Similarity
Hydrodynamic experiment provides key data for Stockpile Stewardship
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AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Homesum_a_epg0_fpd_mmcf_m.xls" ,"Available from WebQuantityBonneville Power Administration would likeUniverse (JournalvivoHighHussein Khalil Hussein KhalilStatistical
Resonances arising from hydrodynamic memory in Brownian motion - The colour of thermal noise
Thomas Franosch; Matthias Grimm; Maxim Belushkin; Flavio Mor; Giuseppe Foffi; László Forró; Sylvia Jeney
2011-08-17
Observation of the Brownian motion of a small probe interacting with its environment is one of the main strategies to characterize soft matter. Essentially two counteracting forces govern the motion of the Brownian particle. First, the particle is driven by the rapid collisions with the surrounding solvent molecules, referred to as thermal noise. Second, the friction between the particle and the viscous solvent damps its motion. Conventionally, the thermal force is assumed to be random and characterized by a white noise spectrum. Friction is assumed to be given by the Stokes drag, implying that motion is overdamped. However, as the particle receives momentum from the fluctuating fluid molecules, it also displaces the fluid in its immediate vicinity. The entrained fluid acts back on the sphere and gives rise to long-range correlation. This hydrodynamic memory translates to thermal forces, which display a coloured noise spectrum. Even 100 years after Perrin's pioneering experiments on Brownian motion, direct experimental observation of this colour has remained elusive. Here, we measure the spectrum of thermal noise by confining the Brownian fluctuations of a microsphere by a strong optical trap. We show that due to hydrodynamic correlations the power spectral density of the spheres positional fluctuations exhibits a resonant peak in strong contrast to overdamped systems. Furthermore, we demonstrate that peak amplification can be achieved through parametric excitation. In analogy to Microcantilever-based sensors our results demonstrate that the particle-fluid-trap system can be considered as a nanomechanical resonator, where the intrinsic hydrodynamic backflow enhances resonance. Therefore, instead of being a disturbance, details in thermal noise can be exploited for the development of new types of sensors and particle-based assays for lab-on-a-chip applications.
Dynamics of suspensions of hydrodynamically structured particles: Analytic theory and experiment
Jonas Riest; Thomas Eckert; Walter Richtering; Gerhard Nägele
2015-01-12
We present an easy-to-use analytic toolbox for the calculation of short-time transport properties of concentrated suspensions of spherical colloidal particles with internal hydrodynamic structure, and direct interactions described by a hard-core or soft Hertz pair potential. The considered dynamic properties include self-diffusion and sedimentation coefficients, the wavenumber-dependent diffusion function determined in dynamic scattering experiments, and the high-frequency shear viscosity. The toolbox is based on the hydrodynamic radius model (HRM) wherein the internal particle structure is mapped on a hydrodynamic radius parameter for unchanged direct interactions, and on an existing simulation data base for solvent-permeable and spherical annulus particles. Useful scaling relations for the diffusion function and self-diffusion coefficient, known to be valid for hard-core interaction, are shown to apply also for soft pair potentials. We further discuss extensions of the toolbox to long-time transport properties including the low-shear zero-frequency viscosity and the long-time self-diffusion coefficient. The versatility of the toolbox is demonstrated by the analysis of a previous light scattering study of suspensions of non-ionic PNiPAM microgels [Eckert et al., J. Chem. Phys., 2008, 129, 124902] in which a detailed theoretical analysis of the dynamic data was left as an open task. By the comparison with Hertz potential based calculations, we show that the experimental data are consistently and accurately described using the Verlet-Weis corrected Percus-Yevick structure factor as input, and for a solvent penetration length equal to three percent of the excluded volume radius. This small solvent permeability of the microgel particles has a significant dynamic effect at larger concentrations.
Lee, Lai Yeng
This paper presents the fabrication of controlled release devices for anticancer drug paclitaxel using supercritical antisolvent method. The thermodynamic and hydrodynamic effects during supercritical antisolvent process ...
Jacquez, Edward B [Los Alamos National Laboratory
2008-01-01
The mission of the Dual Axis Radiograph Hydrodynamic Test (DARHT) Facility is to conduct experiments on dynamic events of extremely dense materials. The PSS control system is designed specifically to prevent personnel from becoming exposed to radiation and explosive hazards during machine operations and/or the firing site operation. This paper will outline the Radiation Safety System (RSS) and the High Explosive Safety System (HESS) which are computer-controlled sets of positive interlocks, warning devices, and other exclusion mechanisms that together form the PSS.
Somasundaram, Deepak S [UNLV; Trabia, Mohamed [UNLV; O'Toole, Brendan [UNLV; Hixson, Robert S [NSTec
2014-01-23
This paper describes our work to characterize the variables affecting the smoothed particle hydrodynamics (SPH) method in the LS-DYNA package for simulating high-velocity flyer plate impact experiments. LS-DYNA simulations are compared with one-dimensional experimental data of an oxygen-free high-conductivity (OFHC) copper flyer plate impacting another plate of the same material. The comparison is made by measuring the velocity of a point on the back surface of the impact plate using the velocity interferometer system for any reflector (VISAR) technique.
Knudsen-Hydrodynamic Crossover in Liquid 3He in High Porosity Aerogel
Takeuchi, H; Nagai, K; Choi, H C; Moon, B H; Masuhara, N; Meisel, M W; Lee, Y; Mulders, N
2012-01-01
We present a combined experimental and theoretical study of the drag force acting on a high porosity aerogel immersed in liquid ${}^3$He and its effect on sound propagation. The drag force is characterized by the Knudsen number, which is defined as the ratio of the quasiparticle mean free path to the radius of an aerogel strand. Evidence of the Knudsen-hydrodynamic crossover is clearly demonstrated by a drastic change in the temperature dependence of ultrasound attenuation in 98% porosity aerogel. Our theoretical analysis shows that the frictional sound damping caused by the drag force is governed by distinct laws in the two regimes, providing excellent agreement with the experimental observation.
Hydrodynamic models for slurry bubble column reactors. Fourth technical progress report
Gidaspow, D.
1995-07-01
The objective of this investigation is to convert our ``learning gas-solid-liquid`` fluidization model into a predictive design model. The IIT hydrodynamic model computes the phase velocities and volume fractions of gas, liquid and particulate phases. Model verification involves a comparison of these computed velocities and volume fractions to experimental values. The simulation of Air Product methanol reactors described in this paper are continuing. Granular temperatures and viscosities have been computed. Preliminary measurements of granular temperatures using the Air Product catalysts were obtained using our CCD camera.
Transport coefficients of off-lattice mesoscale-hydrodynamics simulation techniques
Hiroshi Noguchi; Gerhard Gompper
2008-04-14
The viscosity and self-diffusion constant of particle-based mesoscale hydrodynamic methods, multi-particle collision dynamics (MPC) and dissipative particle dynamics (DPD), are investigated, both with and without angular-momentum conservation. Analytical results are derived for fluids with an ideal-gas equation of state and a finite-time-step dynamics, and compared with simulation data. In particular, the viscosity is derived in a general form for all variants of the MPC method. In general, very good agreement between theory and simulations is obtained.
Goncharov, V. N.; Sangster, T. C.; Betti, R.; Boehly, T. R.; Bonino, M. J.; Collins, T. J. B.; Craxton, R. S.; Delettrez, J. A.; Edgell, D. H.; Epstein, R.; Follett, R. K.; Forrest, C. J.; Froula, D. H.; Glebov, V. Yu.; Harding, D. R.; Henchen, R. J.; Hu, S. X.; Igumenshchev, I. V.; Janezic, R.; Kelly, J. H. [Laboratory for Laser Energetics, University of Rochester, Rochester, New York 14623 (United States); and others
2014-05-15
Reaching ignition in direct-drive (DD) inertial confinement fusion implosions requires achieving central pressures in excess of 100 Gbar. The OMEGA laser system [T. R. Boehly et al., Opt. Commun. 133, 495 (1997)] is used to study the physics of implosions that are hydrodynamically equivalent to the ignition designs on the National Ignition Facility (NIF) [J. A. Paisner et al., Laser Focus World 30, 75 (1994)]. It is shown that the highest hot-spot pressures (up to 40 Gbar) are achieved in target designs with a fuel adiabat of ? ? 4, an implosion velocity of 3.8?×?10{sup 7}?cm/s, and a laser intensity of ?10{sup 15}?W/cm{sup 2}. These moderate-adiabat implosions are well understood using two-dimensional hydrocode simulations. The performance of lower-adiabat implosions is significantly degraded relative to code predictions, a common feature between DD implosions on OMEGA and indirect-drive cryogenic implosions on the NIF. Simplified theoretical models are developed to gain physical understanding of the implosion dynamics that dictate the target performance. These models indicate that degradations in the shell density and integrity (caused by hydrodynamic instabilities during the target acceleration) coupled with hydrodynamics at stagnation are the main failure mechanisms in low-adiabat designs. To demonstrate ignition hydrodynamic equivalence in cryogenic implosions on OMEGA, the target-design robustness to hydrodynamic instability growth must be improved by reducing laser-coupling losses caused by cross beam energy transfer.
Performance evaluation of half-wetted hydrodynamic bearings with DLC coated surfaces.
Eryilmaz, O.; Erdemir, A.; Energy Systems
2008-01-01
In conventional liquid lubrication it is assumed that surfaces are fully wetted and no slip occurs between the fluid and the solid boundary. Under the 'no slip' condition the maximum shear gradient occurs at the fluid-surface interface. When one or both surfaces are non-wetted by the fluid, boundary slip can occur due to weak bonding between the fluid and the solid surface, which reduces shear stresses in the fluid adjacent to the non-wetted surface. A thrust bearing tribometer was used to compare the performance of 'no slip' hydrodynamic thrust bearings with bearings surfaces that were made to slip at the interface between the surface and fluid. Hydrophobic surfaces on both runner and bearing were achieved with the deposition of hydrogenated diamond like carbon (H-DLC) films, produced by plasma-enhanced CVD on titanium alloy surfaces. Hydrophilic surfaces were created through the surface modification of DLC. A mixtures of water and glycerol was used as the lubricant. The tests were conducted using different constant bearing gaps. The normal load and the torque or traction force between the rotating runner and hydrodynamic thrust bearing were measured with load cells. The experimental results confirmed that load support is still possible when surfaces are partially-wetted or nonwetted.
General Relativistic Hydrodynamic Simulation of Accretion Flow from a Stellar Tidal Disruption
Shiokawa, Hotaka; Cheng, Roseanne M; Piran, Tsvi; Noble, Scott C
2015-01-01
We study how the matter dispersed when a supermassive black hole tidally disrupts a star joins an accretion flow. Combining a relativistic hydrodynamic simulation of the stellar disruption with a relativistic hydrodynamics simulation of the tidal debris motion, we track such a system until ~80% of the stellar mass bound to the black hole has settled into an accretion flow. Shocks near the stellar pericenter and also near the apocenter of the most tightly-bound debris dissipate orbital energy, but only enough to make the characteristic radius comparable to the semi-major axis of the most-bound material, not the tidal radius as previously thought. The outer shocks are caused by post-Newtonian effects, both on the stellar orbit during its disruption and on the tidal forces. Accumulation of mass into the accretion flow is non-monotonic and slow, requiring ~3--10x the orbital period of the most tightly-bound tidal streams, while the inflow time for most of the mass may be comparable to or longer than the mass accu...
Selective evaporation of focusing fluid in two-fluid hydrodynamic print head.
Keicher, David M.; Cook, Adam W.
2014-09-01
The work performed in this project has demonstrated the feasibility to use hydrodynamic focusing of two fluid steams to create a novel micro printing technology for electronics and other high performance applications. Initial efforts focused solely on selective evaporation of the sheath fluid from print stream provided insight in developing a unique print head geometry allowing excess sheath fluid to be separated from the print flow stream for recycling/reuse. Fluid flow models suggest that more than 81 percent of the sheath fluid can be removed without affecting the print stream. Further development and optimization is required to demonstrate this capability in operation. Print results using two-fluid hydrodynamic focusing yielded a 30 micrometers wide by 0.5 micrometers tall line that suggests that the cross-section of the printed feature from the print head was approximately 2 micrometers in diameter. Printing results also demonstrated that complete removal of the sheath fluid is not necessary for all material systems. The two-fluid printing technology could enable printing of insulated conductors and clad optical interconnects. Further development of this concept should be pursued.
Peterson, J. L.; Clark, D. S.; Suter, L. J. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States); Masse, L. P. [CEA, DAM, DIF, 91297 Arpajon (France)
2014-09-15
Defects on inertial confinement fusion capsule surfaces can seed hydrodynamic instability growth and adversely affect capsule performance. The dynamics of shocks launched during the early period of x-ray driven National Ignition Facility (NIF) implosions determine whether perturbations will grow inward or outward at peak implosion velocity and final compression. In particular, the strength of the first shock, launched at the beginning of the laser pulse, plays an important role in determining Richtmyer-Meshkov (RM) oscillations on the ablation front. These surface oscillations can couple to the capsule interior through subsequent shocks before experiencing Rayleigh-Taylor (RT) growth. We compare radiation hydrodynamic simulations of NIF implosions to analytic theories of the ablative RM and RT instabilities to illustrate how early time laser strength can alter peak velocity growth. We develop a model that couples the RM and RT implosion phases and captures key features of full simulations. We also show how three key parameters can control the modal demarcation between outward and inward growth.
Optimization of a Two-Fluid Hydrodynamic Model of Churn-Turbulent Flow
Donna Post Guillen
2009-07-01
A hydrodynamic model of two-phase, churn-turbulent flows is being developed using the computational multiphase fluid dynamics (CMFD) code, NPHASE-CMFD. The numerical solutions obtained by this model are compared with experimental data obtained at the TOPFLOW facility of the Institute of Safety Research at the Forschungszentrum Dresden-Rossendorf. The TOPFLOW data is a high quality experimental database of upward, co-current air-water flows in a vertical pipe suitable for validation of computational fluid dynamics (CFD) codes. A five-field CMFD model was developed for the continuous liquid phase and four bubble size groups using mechanistic closure models for the ensemble-averaged Navier-Stokes equations. Mechanistic models for the drag and non-drag interfacial forces are implemented to include the governing physics to describe the hydrodynamic forces controlling the gas distribution. The closure models provide the functional form of the interfacial forces, with user defined coefficients to adjust the force magnitude. An optimization strategy was devised for these coefficients using commercial design optimization software. This paper demonstrates an approach to optimizing CMFD model parameters using a design optimization approach. Computed radial void fraction profiles predicted by the NPHASE-CMFD code are compared to experimental data for four bubble size groups.
Analytical and numerical Gubser solutions of the second-order hydrodynamics
Long-Gang Pang; Yoshitaka Hatta; Xin-Nian Wang; Bo-Wen Xiao
2015-04-25
Evolution of quark-gluon plasma (QGP) near equilibrium can be described by the second-order relativistic viscous hydrodynamic equations. Consistent and analytically verifiable numerical solutions are critical for phenomenological studies of the collective behavior of QGP in high-energy heavy-ion collisions. A novel analytical solution based on the conformal Gubser flow which is a boost-invariant solution with transverse fluid velocity is presented. Due to the non-linear nature of the equation, the analytical solution is non-perturbative and exhibits features that are rather distinct from solutions to usual linear hydrodynamic equations. It is used to verify with high precision the numerical solution with a newly developed state-of-the-art $(3+1)$-dimensional second-order viscous hydro code (CLVisc). The perfect agreement between the analytical and numerical solutions demonstrates the reliability of the numerical simulations with the second-order viscous corrections. This lays the foundation for future phenomenological studies that allow one to gain access to the second-order transport coefficients.
Shao, Yan-Lin Faltinsen, Odd M.
2014-10-01
We propose a new efficient and accurate numerical method based on harmonic polynomials to solve boundary value problems governed by 3D Laplace equation. The computational domain is discretized by overlapping cells. Within each cell, the velocity potential is represented by the linear superposition of a complete set of harmonic polynomials, which are the elementary solutions of Laplace equation. By its definition, the method is named as Harmonic Polynomial Cell (HPC) method. The characteristics of the accuracy and efficiency of the HPC method are demonstrated by studying analytical cases. Comparisons will be made with some other existing boundary element based methods, e.g. Quadratic Boundary Element Method (QBEM) and the Fast Multipole Accelerated QBEM (FMA-QBEM) and a fourth order Finite Difference Method (FDM). To demonstrate the applications of the method, it is applied to some studies relevant for marine hydrodynamics. Sloshing in 3D rectangular tanks, a fully-nonlinear numerical wave tank, fully-nonlinear wave focusing on a semi-circular shoal, and the nonlinear wave diffraction of a bottom-mounted cylinder in regular waves are studied. The comparisons with the experimental results and other numerical results are all in satisfactory agreement, indicating that the present HPC method is a promising method in solving potential-flow problems. The underlying procedure of the HPC method could also be useful in other fields than marine hydrodynamics involved with solving Laplace equation.
Robinson, A. P. L.; Schmitz, H. [Central Laser Facility, STFC Rutherford-Appleton Laboratory, Didcot OX11 0QX (United Kingdom)] [Central Laser Facility, STFC Rutherford-Appleton Laboratory, Didcot OX11 0QX (United Kingdom); Pasley, J. [Central Laser Facility, STFC Rutherford-Appleton Laboratory, Didcot OX11 0QX (United Kingdom) [Central Laser Facility, STFC Rutherford-Appleton Laboratory, Didcot OX11 0QX (United Kingdom); York Plasma Institute, University of York, York YO10 5DD (United Kingdom)
2013-12-15
Resistively guiding laser-generated fast electron beams in targets consisting of a resistive wire embedded in lower Z material should allow one to rapidly heat the wire to over 100 eV over a substantial distance without strongly heating the surrounding material. On the multi-ps timescale, this can drive hydrodynamic motion in the surrounding material. Thus, ultra-intense laser solid interactions have the potential as a controlled driver of radiation hydrodynamics in solid density material. In this paper, we assess the laser and target parameters needed to achieve such rapid and controlled heating of the embedded wire.
Modifications of Carbonate Fracture Hydrodynamic Properties by CO{sub 2}-Acidified Brine Flow
Deng, Hang; Ellis, Brian R.; Peters, Catherine A.; Fitts, Jeffrey P.; Crandall, Dustin; Bromhal, Grant S.
2013-08-01
Acidic reactive flow in fractures is relevant in subsurface activities such as CO{sub 2} geological storage and hydraulic fracturing. Understanding reaction-induced changes in fracture hydrodynamic properties is essential for predicting subsurface flows such as leakage, injectability, and fluid production. In this study, x-ray computed tomography scans of a fractured carbonate caprock were used to create three dimensional reconstructions of the fracture before and after reaction with CO{sub 2}-acidified brine (Ellis et al., 2011, Greenhouse Gases: Sci. Technol., 1:248-260). As expected, mechanical apertures were found to increase substantially, doubling and even tripling in some places. However, the surface geometry evolved in complex ways including ‘comb-tooth’ structures created from preferential dissolution of calcite in transverse sedimentary bands, and the creation of degraded zones, i.e. porous calcite-depleted areas on reacted fracture surfaces. These geometric alterations resulted in increased fracture roughness, as measured by surface Z{sub 2} parameters and fractal dimensions D{sub f}. Computational fluid dynamics (CFD) simulations were conducted to quantify the changes in hydraulic aperture, fracture transmissivity and permeability. The results show that the effective hydraulic apertures are smaller than the mechanical apertures, and the changes in hydraulic apertures are nonlinear. Overestimation of flow rate by a factor of two or more would be introduced if fracture hydrodynamic properties were based on mechanical apertures, or if hydraulic aperture is assumed to change proportionally with mechanical aperture. The differences can be attributed, in part, to the increase in roughness after reaction, and is likely affected by contiguous transverse sedimentary features. Hydraulic apertures estimated by the 1D statistical model and 2D local cubic law (LCL) model are consistently larger than those calculated from the CFD simulations. In addition, a novel ternary segmentation method was devised to handle the degraded zones, allowing for a bounding analysis of the effects on hydraulic properties. We found that the degraded zones account for less than 15% of the fracture volume, but cover 70% to 80% of the fracture surface. When the degraded zones are treated as part of the fracture, the fracture transmissivities are two to four times larger because the fracture surfaces after reaction are not as rough as they would be if one considers the degraded zone as part of the rock. Therefore, while degraded zones created during geochemical reactions may not significantly increase mechanical aperture, this type of feature cannot be ignored and should be treated with prudence when predicting fracture hydrodynamic properties.
Reynolds, Christopher S.
AGN FEEDBACK AND COOLING FLOWS: PROBLEMS WITH SIMPLE HYDRODYNAMIC MODELS John C. Vernaleo the cooling of the virialized intracluster medium (ICM) in the inner regions of galaxy clusters, solving the cooling flow problem and explaining the high-mass truncation of the galaxy luminosity function. We explore
Luding, Stefan
The 7th World Congress on Particle Technology (WCPT7) Towards hydrodynamic simulations of wet !!, !!, !! inner/ split/ outer radius of shear cell [m] ! filling height [m] (r, , z) cylindrical coordinates [m migration across the contacts, affects the shear band structure [6] and different liquid bridge models were
Barz, H.W.; Csernai, L.P.; Greiner, W.
1982-08-01
The collision process is described by hydrodynamical equations. The escape of nucleons which do not take part in the thermal equilibrium are considered by including drain terms in these equations. The energy spectra of the escaped nucleons and of nucleons evaporated after the break up of the fluid are compared.
T. Csorgo; M. I. Nagy; M. Csanad
2007-04-17
A new class of accelerating, exact, explicit and simple solutions of relativistic hydrodynamics is presented. Since these new solutions yield a finite rapidity distribution, they lead to an advanced estimate of the initial energy density and life-time of high energy heavy ion reactions. Accelerating solutions are also given for spherical expansions in arbitrary number of spatial dimensions.
technologies, including surface vessels, underwater vehicles, offshore platforms, and wave-energy converters they will encounter in order to minimize hydrodynamic and structural loads. However, the recent emergence of the wave energy industry has seen the deployment of WECs that are designed specifically to have resonance
Egecioglu, Ömer
1997-01-01
to a problem in kinetic theory, namely, the dynamics of liquid crystalline polymers (LCPs). It is a Lagrangian technique; Liquid crystalline polymers; Smoothed particle hydrodynamics 1. Introduction 1.1. Kinetic theory for the solution of kinetic theory problems Part 1" Method C.V. Chaubal a, A. Srinivasan b, ~). E~ecio~lu b, L
Fish, Frank
1991-01-01
THE JOURNAL OF EXPERIMENTAL ZOOLOGY 258164-173 (1991) Hydrodynamics of the Feet of Fish-Catching Bats: Influence of the Water Surface on Drag and Morphological Design FRANK E. FISH, BRAD R. BLOOD and Pizonyx uiuesi, display similar hind foot mor- phologies specialized for their fish-catching habits
Scaling theory for hydrodynamic lubrication, with application to non-Newtonian lubricants
Patrick B. Warren
2015-02-04
Scaling arguments are developed for the load balance in hydrodynamic lubrication, and applied to non-Newtonian lubricants with a shear-thinning rheology typical of a structured liquid. It is argued that the shear thinning regime may be mechanically unstable in lubrication flow, and consequently the Stribeck (friction) curve should be discontinuous, with possible hysteresis. Further analysis suggests that normal stress and flow transience (stress overshoot) do not destroy this basic picture, although they may provide stabilising mechanisms at higher shear rates. Extensional viscosity is also expected to be insignificant unless the Trouton ratio is large. A possible application to recent theories of shear thickening in non-Brownian particulate suspensions is indicated.
Hydrodynamic Collective Effects of Active Protein Machines in Solution and Lipid Bilayers
Alexander Mikhailov; Raymond Kapral
2015-03-09
The cytoplasm and biomembranes in biological cells contain large numbers of proteins that cyclically change their shapes. They are molecular machines that can function as molecular motors or carry out many other tasks in the cell. We analyze the effects that hydrodynamic flows induced by active proteins have on other passive molecules in solution or membranes. We show that the diffusion constants of passive particles are enhanced substantially. Furthermore, when gradients of active proteins are present, a chemotaxis-like drift of passive particles takes place. In lipid bilayers, the effects are strongly nonlocal, so that active inclusions in the membrane contribute to diffusion enhancement and the drift. The results indicate that the transport properties of passive particles in systems containing active proteins machines operating under nonequilibrium conditions differ from their counterparts in systems at thermal equilibrium.
Shunsuke Yabunaka; Ryuichi Okamoto; Akira Onuki
2015-05-23
We investigate bridging and aggregation of two colloidal particles in a near-critical binary mixture when the fluid far from the particles is outside the coexistence (CX) curve and is rich in the component disfavored by the colloid surfaces. In such situations, the adsorption-induced interaction is enhanced, leading to bridging and aggregation of the particles. We realize bridging firstly by changing the temperature with a fixed interparticle separation and secondly by letting the two particles aggregate. The interparticle attractive force dramatically increases upon bridging. The dynamics is governed by hydrodynamic flow around the colloid surfaces. In aggregation, the adsorption layers move with the particles and squeezing occurs at narrow separation. We take into account the renormalization effect due to the critical fluctuations using the recent local functional theory [J. Chem. Phys. 136, 114704 (2012)].
Toytman, Ilya; Simanovski, Dmitri; Palanker, Daniel
2010-01-01
Transparent biological tissues can be precisely dissected with ultrafast lasers using optical breakdown in the tight focal zone. Typically, tissues are cut by sequential application of pulses, each of which produces a single cavitation bubble. We investigate the hydrodynamic interactions between simultaneous cavitation bubbles originating from multiple laser foci. Simultaneous expansion and collapse of cavitation bubbles can enhance the cutting efficiency by increasing the resulting deformations in tissue, and the associated rupture zone. An analytical model of the flow induced by the bubbles is presented and experimentally verified. The threshold strain of the material rupture is measured in a model tissue. Using the computational model and the experimental value of the threshold strain one can compute the shape of the rupture zone in tissue resulting from application of multiple bubbles. With the threshold strain of 0.7 two simultaneous bubbles produce a continuous cut when applied at the distance 1.35 time...
Complete relativistic second-order dissipative hydrodynamics from the entropy principle
Jaiswal, Amaresh; Pal, Subrata
2013-01-01
We present a new derivation of relativistic dissipative hydrodynamic equations, which invokes the second law of thermodynamics for the entropy four-current expressed in terms of the single-particle phase-space distribution function obtained from Grad's 14-moment approximation. This derivation is complete in the sense that all the second-order transport coefficients are uniquely determined within a single theoretical framework. In particular, this removes the long-standing ambiguity in the relaxation time for bulk viscosity thereby eliminating one of the uncertainties in the extraction of the shear viscosity to entropy density ratio from confrontation with the anisotropic flow data in relativistic heavy-ion collisions. We find that in the one-dimensional scaling expansion, these transport coefficients prevent the occurrence of cavitation even for rather large values of the bulk viscosity estimated in lattice QCD.
Complete relativistic second-order dissipative hydrodynamics from the entropy principle
Amaresh Jaiswal; Rajeev S. Bhalerao; Subrata Pal
2013-02-04
We present a new derivation of relativistic dissipative hydrodynamic equations, which invokes the second law of thermodynamics for the entropy four-current expressed in terms of the single-particle phase-space distribution function obtained from Grad's 14-moment approximation. This derivation is complete in the sense that all the second-order transport coefficients are uniquely determined within a single theoretical framework. In particular, this removes the long-standing ambiguity in the relaxation time for bulk viscosity thereby eliminating one of the uncertainties in the extraction of the shear viscosity to entropy density ratio from confrontation with the anisotropic flow data in relativistic heavy-ion collisions. We find that in the one-dimensional scaling expansion, these transport coefficients prevent the occurrence of cavitation even for rather large values of the bulk viscosity estimated in lattice QCD.
Gan, Yanbiao; Zhang, Guangcai; Succi, Sauro
2015-01-01
A discrete Boltzmann model (DBM) is developed to investigate the hydrodynamic and thermodynamic non-equilibrium (TNE) effects in phase separation process. The interparticle forces drive changes and the gradient force, induced by gradients of macroscopic quantities, oppose them. In this paper we investigate the interplay between them by providing detailed inspection of various non-equilibrium observables. Based on the TNE features, we define a TNE strength which roughly estimates the deviation amplitude from the thermodynamic equilibrium. The time evolution of the TNE intensity provides a convenient and efficient physical criterion to separate the stages of the spinodal decomposition and domain growth. Via the DBM simulation and this criterion, we quantitatively study the effects of latent heat and surface tension on phase separation. It is found that, the TNE strength attains its maximum at the end of the spinodal decomposition stage, and it decreases when the latent heat increases from zero. The surface tens...
On the explanation and calculation of anomalous reflood hydrodynamics in large PWR cores
Rodriguez, S.E.
1985-01-01
Reflood hydrodynamics from large-scale (1:20) test facilities in Japan have yielded apparently anomalous behavior relative to FLECHT tests. Namely, even at reflooding rates below one inch per second, very large liquid volume fractions (10-15%) exist above the quench fronts shortly after flood begins; thus cladding temperature excursions are terminated early in the reflood phase. This paper discusses an explanation for this behavior: liquid films on the core's unheated rods. The experimental findings are shown to be correctly simulated with a new four-field (vapor, films, droplets) version of the best-estimate TRAC-PF1 computer code, TRAC-FF. These experimental and analytical findings have important implications for PWR large-break LOCA licensing.
Abhrajit Laskar; Rajeev Singh; Somdeb Ghose; Gayathri Jayaraman; P. B. Sunil Kumar; R. Adhikari
2013-06-11
Non-equilibrium processes which convert chemical energy into mechanical motion enable the motility of organisms. Bundles of inextensible filaments driven by energy transduction of molecular motors form essential components of micron-scale motility engines like cilia and flagella. The mimicry of cilia-like motion in recent experiments on synthetic active filaments supports the idea that generic physical mechanisms may be sufficient to generate such motion. Here we show, theoretically, that the competition between the destabilising effect of hydrodynamic interactions induced by force-free and torque-free chemomechanically active flows, and the stabilising effect of nonlinear elasticity, provides a generic route to spontaneous oscillations in active filaments. These oscillations, reminiscent of prokaryotic and eukaryotic flagellar motion, are obtained without having to invoke structural complexity or biochemical regulation. This minimality implies that biomimetic oscillations, previously observed only in complex bundles of active filaments, can be replicated in simple chains of generic chemomechanically active beads.
Andronov, V.A.; Zhidov, I.G.; Meskov, E.E.; Nevmerzhitskii, N.V.; Nikiforov, V.V.; Razin, A.N.; Rogatchev, V.G.; Tolshmyakov, A.I.; Yanilkin, Yu.V.
1995-02-01
This report describes an extensive program of investigations conducted at Arzamas-16 in Russia over the past several decades. The focus of the work is on material interface instability and the mixing of two materials. Part 1 of the report discusses analytical and computational studies of hydrodynamic instabilities and turbulent mixing. The EGAK codes are described and results are illustrated for several types of unstable flow. Semiempirical turbulence transport equations are derived for the mixing of two materials, and their capabilities are illustrated for several examples. Part 2 discusses the experimental studies that have been performed to investigate instabilities and turbulent mixing. Shock-tube and jelly techniques are described in considerable detail. Results are presented for many circumstances and configurations.
A review of hydrodynamic investigations into arrays of ocean wave energy converters
De Chowdhury, S; Sanchez, A Madrigal; Fleming, A; Winship, B; Illesinghe, S; Toffoli, A; Babanin, A; Penesis, I; Manasseh, R
2015-01-01
Theoretical, numerical and experimental studies on arrays of ocean wave energy converter are reviewed. The importance of extracting wave power via an array as opposed to individual wave-power machines has long been established. There is ongoing interest in implementing key technologies at commercial scale owing to the recent acceleration in demand for renewable energy. To date, several reviews have been published on the science and technology of harnessing ocean-wave power. However, there have been few reviews of the extensive literature on ocean wave-power arrays. Research into the hydrodynamic modelling of ocean wave-power arrays is analysed. Where ever possible, comparisons are drawn with physical scaled experiments. Some critical knowledge gaps have been found. Specific emphasis has been paid on understanding how the modelling and scaled experiments are likely to be complementary to each other.
Non-equilibrium thermo-hydrodynamic effects on the Rayleigh-Taylor instability in compressible flows
Huilin Lai; Aiguo Xu; Guangcai Zhang; Yanbiao Gan; Yangjun Ying; Sauro Succi
2015-07-04
A discrete Boltzmann model (DBM) is developed to investigate the Rayleigh-Taylor instability (RTI) in compressible flows. Compressibility effects are investigated by inspecting the interplay between thermodynamic and hydrodynamic non-equilibrium manifestations (TNE, HNE, respectively) and their impact on the dynamics of the bubble and the spike at the interface between the heavy and the light fluid. To this purpose, two effective approaches are presented, one tracking the \\emph{local} TNE manifestations and the other focussing on the mean temperature of the flow. Both compressibility effect and the \\emph{global} TNE intensity show different trends in the initial and the later stages of the instability. Compressibility is found to retard the initial stage of the RTI and accelerate the later one. It is also found that TNE effects are generally enhanced by compressibility, especially in the later stage of the instability.
Mixed-RKDG Finite Element Methods for the 2-D Hydrodynamic Model for Semiconductor Device Simulation
DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)
Chen, Zhangxin; Cockburn, Bernardo; Jerome, Joseph W.; Shu, Chi-Wang
1995-01-01
In this paper we introduce a new method for numerically solving the equations of the hydrodynamic model for semiconductor devices in two space dimensions. The method combines a standard mixed finite element method, used to obtain directly an approximation to the electric field, with the so-called Runge-Kutta Discontinuous Galerkin (RKDG) method, originally devised for numerically solving multi-dimensional hyperbolic systems of conservation laws, which is applied here to the convective part of the equations. Numerical simulations showing the performance of the new method are displayed, and the results compared with those obtained by using Essentially Nonoscillatory (ENO) finite difference schemes. Frommore »the perspective of device modeling, these methods are robust, since they are capable of encompassing broad parameter ranges, including those for which shock formation is possible. The simulations presented here are for Gallium Arsenide at room temperature, but we have tested them much more generally with considerable success.« less
Minimum entropy production closure of the photo-hydrodynamic equations for radiative heat transfer
Thomas Christen; Frank Kassubek
2008-12-17
In the framework of a two-moment photo-hydrodynamic modelling of radiation transport, we introduce a concept for the determination of effective radiation transport coefficients based on the minimization of the local entropy production rate of radiation and matter. The method provides the nonequilibrium photon distribution from which the effective absorption coefficients and the variable Eddington factor (VEF) can be calculated. The photon distribution depends on the frequency dependence of the absorption coefficient, in contrast to the distribution obtained by methods based on entropy maximization. The calculated mean absorption coefficients are not only correct in the limit of optically thick and thin media, but even provide a reasonable interpolation in the cross-over regime between these limits, notably without introducing any fit parameter. The method is illustrated and discussed for grey matter and for a simple example of non-grey matter with a two-band absorption spectrum. The method is also briefly compared with the maximum entropy concept.
C. B. Korn; U. S. Schwarz
2008-06-27
For a cell moving in hydrodynamic flow above a wall, translational and rotational degrees of freedom are coupled by the Stokes equation. In addition, there is a close coupling of convection and diffusion due to the position-dependent mobility. These couplings render calculation of the mean encounter time between cell surface receptors and ligands on the substrate very difficult. Here we show for a two-dimensional model system how analytical progress can be achieved by treating motion in the vertical direction by an effective reaction term in the mean first passage time equation for the rotational degree of freedom. The strength of this reaction term can either be estimated from equilibrium considerations or used as a fit parameter. Our analytical results are confirmed by computer simulations and allow to assess the relative roles of convection and diffusion for different scaling regimes of interest.
Charles Reece; John Mammosser; Jun Ortega
2008-02-12
Multi-cell niobium cavities often obtain the highest performance levels after having been subjected to an electropolishing (EP) process. The horizontal EP process first developed at KEK/Nomura Plating for TRISTAN[1] cavities is being applied to TESLA-style cavities and other structures for the XFEL and ILC R&D. Jefferson Lab is presently carrying this activity in the US. Because the local electropolishing current density is highly temperature dependent, we have created using CFDesign™ a full-scale hydrodynamic model which simulates the various thermal conditions present during 9-cell cavity electropolishing. The results of these simulations are compared with exterior surface temperature data gathered during ILC cavity EP at JLab. Having benchmarked the simulation, we explore the affect of altered boundary conditions in order to evaluate potentially beneficial modifications to the current standard process.
Hydrodynamic and mass transfer characteristics in a large-scale slurry bubble column reactor
Inga, J.R. [Air Products and Chemicals, Allentown, PA (United States); Morsi, B.I. [Univ. of Pittsburgh, PA (United States). Chemical and Petroleum Engineering Dept.
1998-12-31
The hydrodynamic and mass transfer characteristics were measured for various gases (H{sub 2}, CO, N{sub 2} and CH{sub 4}) in a liquid hexane mixture in the presence and absence of actual Fischer-Tropsch catalyst using a 0.3-m diameter, 2.8-m tall slurry bubble column reactor. The reactor was operated in the churn-turbulent regime with superficial gas velocities reaching 0.25 m/s, catalyst concentrations up to 50 wt.% and pressures up to 8 bar. The experimental gas holdup and the mass transfer coefficient values for the four gases were found to increase with the superficial gas velocity and pressure. The values, however, appeared to decrease with increasing catalyst concentration.
Investigating puzzling aspects of the quantum theory by means of its hydrodynamic formulation
Sanz, A S
2015-01-01
Bohmian mechanics, a hydrodynamic formulation of the quantum theory, constitutes a useful resource to analyze the role of the phase as the mechanism responsible for the dynamical evolution of quantum systems. Here this role is discussed in the context of quantum interference. Specifically, it is shown that when dealing with two wave-packet coherent superpositions this phenomenon is analogous to an effective collision of a single wave packet with a barrier. This effect is illustrated by means of a numerical simulation of Young's two-slit experiment. Furthermore, outcomes from this analysis are also applied to a realistic simulation of Wheeler's delayed choice experiment. As it is shown, in both cases the Bohmian formulation helps to understand in a natural way (and, therefore, to demystify) what are typically regarded as paradoxical aspects of the quantum theory, simply stressing the important dynamical role played by the quantum phase. Accordingly, our conception of quantum systems should not rely on artifici...
Generalized Virasoro algebra: left-symmetry and related algebraic and hydrodynamic properties
Mahouton Norbert Hounkonnou; Partha Guha; Tudor Ratiu
2015-10-13
Motivated by the work of Kupershmidt (J. Nonlin. Math. Phys. 6 (1998), 222 --245) we discuss the occurrence of left symmetry in a generalized Virasoro algebra. The multiplication rule is defined, which is necessary and sufficient for this algebra to be quasi-associative. Its link to geometry and nonlinear systems of hydrodynamic type is also recalled. Further, the criteria of skew-symmetry, derivation and Jacobi identity making this algebra into a Lie algebra are derived. The coboundary operators are defined and discussed. We deduce the hereditary operator and its generalization to the corresponding $3-$ary bracket. Further, we derive the so-called $\\rho-$compatibility equation and perform a phase-space extension. Finally, concrete relevant particular cases are investigated.
Wang, Taiping; Yang, Zhaoqing; Khangaonkar, Tarang
2010-04-22
In this study, a hydrodynamic model based on the unstructured-grid finite volume coastal ocean model (FVCOM) was developed for Bellingham Bay, Washington. The model simulates water surface elevation, velocity, temperature, and salinity in a three-dimensional domain that covers the entire Bellingham Bay and adjacent water bodies, including Lummi Bay, Samish Bay, Padilla Bay, and Rosario Strait. The model was developed using Pacific Northwest National Laboratory’s high-resolution Puget Sound and Northwest Straits circulation and transport model. A sub-model grid for Bellingham Bay and adjacent coastal waters was extracted from the Puget Sound model and refined in Bellingham Bay using bathymetric light detection and ranging (LIDAR) and river channel cross-section data. The model uses tides, river inflows, and meteorological inputs to predict water surface elevations, currents, salinity, and temperature. A tidal open boundary condition was specified using standard National Oceanic and Atmospheric Administration (NOAA) predictions. Temperature and salinity open boundary conditions were specified based on observed data. Meteorological forcing (wind, solar radiation, and net surface heat flux) was obtained from NOAA real observations and National Center for Environmental Prediction North American Regional Analysis outputs. The model was run in parallel with 48 cores using a time step of 2.5 seconds. It took 18 hours of cpu time to complete 26 days of simulation. The model was calibrated with oceanographic field data for the period of 6/1/2009 to 6/26/2009. These data were collected specifically for the purpose of model development and calibration. They include time series of water-surface elevation, currents, temperature, and salinity as well as temperature and salinity profiles during instrument deployment and retrieval. Comparisons between model predictions and field observations show an overall reasonable agreement in both temporal and spatial scales. Comparisons of root mean square error values for surface elevation, velocity, temperature, and salinity time series are 0.11 m, 0.10 m/s, 1.28oC, and 1.91 ppt, respectively. The model was able to reproduce the salinity and temperature stratifications inside Bellingham Bay. Wetting and drying processes in tidal flats in Bellingham Bay, Samish Bay, and Padilla Bay were also successfully simulated. Both model results and observed data indicated that water surface elevations inside Bellingham Bay are highly correlated to tides. Circulation inside the bay is weak and complex and is affected by various forcing mechanisms, including tides, winds, freshwater inflows, and other local forcing factors. The Bellingham Bay model solution was successfully linked to the NOAA oil spill trajectory simulation model “General NOAA Operational Modeling Environment (GNOME).” Overall, the Bellingham Bay model has been calibrated reasonably well and can be used to provide detailed hydrodynamic information in the bay and adjacent water bodies. While there is room for further improvement with more available data, the calibrated hydrodynamic model provides useful hydrodynamic information in Bellingham Bay and can be used to support sediment transport and water quality modeling as well as assist in the design of nearshore restoration scenarios.
Hydrodynamical wind on vertically self-gravitating ADAFs in the presence of toroidal magnetic field
Ghasemnezhad, Maryam
2015-01-01
We present the effect of a hydrodynamical wind on the structure and the surface temperature of a vertically self-gravitating magnetized ADAFs using self-similar solutions. Also a model for an axisymmetric, steady-state, vertically self-gravitating hot accretion flow threaded by a toroidal magnetic field has been formulated. The model is based on $\\alpha-$prescription for turbulence viscosity. It is found that the thickness and radial velocity of the disc are reduced significantly as wind gets stronger. In particular, the solutions indicated that the wind and advection have the same effects on the structure of the disc. We also find that in the optically thin ADAF becomes hotter by including the wind parameter and the self-gravity parameter.
THREE-DIMENSIONAL HYDRODYNAMIC BONDI-HOYLE ACCRETION. IV. SPECIFIC HEAT RATIO 4/3.
M. Ruffert
1995-03-06
We investigate the hydrodynamics of three-dimensional classical Bondi-Hoyle accretion. A totally absorbing sphere of different sizes (1, 0.1 and 0.02 accretion radii) exerts gravity on and moves at different Mach numbers (0.6, 1.4, 3.0 and 10) relative to a homogeneous and slightly perturbed medium, which is taken to be an ideal gas ($\\gamma=4/3$). We examine the influence of Mach number of the flow and size of the accretor upon the physical behaviour of the flow and the accretion rates. The hydrodynamics is modeled by the ``Piecewise Parabolic Method'' (PPM). The resolution in the vicinity of the accretor is increased by multiply nesting several $32^3$-zone grids around the sphere, each finer grid being a factor of two smaller in zone dimension than the next coarser grid. This allows us to include a coarse model for the surface of the accretor (vacuum sphere) on the finest grid while at the same time evolving the gas on the coarser grids. For small Mach numbers (0.6 and~1.4) the flow patterns tend towards a steady state, while in the case of supersonic flow (Mach~3 and~10) and small enough accretors, (radius of~0.1 and~0.02 accretion radii) an unstable Mach cone develops, destroying axisymmetry. Our 3D models do not show the highly dynamic flip-flop flow so prominent in 2D calculations performed by other authors. In the gamma=4/3 models, the shock front remains closer to the accretor and the mass accretion rates are higher than in the gamma=5/3 models, whereas the rms of the specific angular momentum accreted does not change.
General Relativistic Hydrodynamic Simulation of Accretion Flow from a Stellar Tidal Disruption
Hotaka Shiokawa; Julian H. Krolik; Roseanne M. Cheng; Tsvi Piran; Scott C. Noble
2015-01-18
We study how the matter dispersed when a supermassive black hole tidally disrupts a star joins an accretion flow. Combining a relativistic hydrodynamic simulation of the stellar disruption with a relativistic hydrodynamics simulation of the tidal debris motion, we track such a system until ~80% of the stellar mass bound to the black hole has settled into an accretion flow. Shocks near the stellar pericenter and also near the apocenter of the most tightly-bound debris dissipate orbital energy, but only enough to make the characteristic radius comparable to the semi-major axis of the most-bound material, not the tidal radius as previously thought. The outer shocks are caused by post-Newtonian effects, both on the stellar orbit during its disruption and on the tidal forces. Accumulation of mass into the accretion flow is non-monotonic and slow, requiring ~3--10x the orbital period of the most tightly-bound tidal streams, while the inflow time for most of the mass may be comparable to or longer than the mass accumulation time. Deflection by shocks does, however, remove enough angular momentum and energy from some mass for it to move inward even before most of the mass is accumulated into the accretion flow. Although the accretion rate rises sharply and then decays roughly as a power-law, its maximum is ~0.1x the previous expectation, and the duration of the peak is ~5x longer than previously predicted. The geometric mean of the black hole mass and stellar mass inferred from a measured event timescale is therefore ~0.2x the value given by classical theory.
The Effect of Roll Waves on the Hydrodynamics of Falling Films Observed in Vertical Column Absorbers
Miller, W.A.
2001-06-28
A thin falling film is well suited to simultaneous heat and mass transfer because of the small thermal resistance through the film and because of the large contact surface achievable at low flow rates. The film enters as a smooth laminar flow and quickly transitions into small-amplitude wavy flow. The waves grown in length and amplitude and are identified as roll waves. This flow regime is termed wavy-laminar flow, and modern heat and mass transfer equipment operate in this complicated transition regime. Research published in open literature has shown the mass flow rate in the rollwaves to be about 10 to 20 times greater than that in the laminar substrate. As the film fully develops, the waves grow in mass and the film substrate thins because fluid is swept from the substrate by the secondary flows of the roll wave. Many studies have been conducted to measure and correlate the film thickness of wavy-laminar flows. Literature data show that Nusselt's theory for smooth laminar flow can over predict the film thickness by as much as 20% for certain wavy-laminar flow conditions. The hydrodynamics of falling films were therefore studied to measure the film thickness of a free-surface falling film and to better understand the parameters that affect the variations of the film thickness. A flow loop was set up for measuring the thickness, wave amplitude,and frequency of a film during hydrodynamic flow. Decreasing the pipe diameter caused the amplitude of the wavy flow to diminish. Measurements monitored from stations along the falling film showed a thinning of film thickness. Fully developed flow required large starting lengths of about 0.5 m. The film thickness increases as the Reynolds number (Re) increases. Increasing the Kapitza number (Ka) causes a decrease in the film thickness. Regression analysis showed that the Re and Ka numbers described the data trends in wavy-laminar flow. Rather than correlating the Re number in discrete ranges of the Ka number as earlier researchers have done, this research made the Ka number an independent regression variable along with the Re number. The correlation explains 96% of the total variation in the data and predicts the experimental data within an absolute average deviation of {+-} 4.0%. The correlation supports the calculation of a fully developed film thickness for wavy-laminar falling films.
da Costa, Fatima Rubio; Petrosian, Vahe'; Carlsson, Mats
2015-01-01
Solar flares involve complex processes that are coupled together and span a wide range of temporal, spatial, and energy scales. Modeling such processes self-consistently has been a challenge in the past. Here we present such a model to simulate the coupling of high-energy particle kinetics with hydrodynamics of the atmospheric plasma. We combine the Stanford unified Fokker-Planck code that models particle acceleration, transport, and bremsstrahlung radiation with the RADYN hydrodynamic code that models the atmospheric response to collisional heating by non-thermal electrons through detailed radiative transfer calculations. We perform simulations using different injection electron spectra, including an {\\it ad hoc} power law and more realistic spectra predicted by the stochastic acceleration model due to turbulence or plasma waves. Surprisingly, stochastically accelerated electrons, even with energy flux $\\ll 10^{10}$ erg s$^{-1}$ cm$^{-2}$, cause "explosive" chromospheric evaporation and drive stronger up- an...
Srinivasan, Bhuvana; Tang, Xian-Zhu
2014-10-15
In an inertial confinement fusion target, energy loss due to thermal conduction from the hot-spot will inevitably ablate fuel ice into the hot-spot, resulting in a more massive but cooler hot-spot, which negatively impacts fusion yield. Hydrodynamic mix due to Rayleigh-Taylor instability at the gas-ice interface can aggravate the problem via an increased gas-ice interfacial area across which energy transfer from the hot-spot and ice can be enhanced. Here, this mix-enhanced transport effect on hot-spot fusion-performance degradation is quantified using contrasting 1D and 2D hydrodynamic simulations, and its dependence on effective acceleration, Atwood number, and ablation speed is identified.
Viallet, M; Walder, R
2011-01-01
This paper describes the first steps of development of a new multidimensional time implicit code devoted to the study of hydrodynamical processes in stellar interiors. The code solves the hydrodynamical equations in spherical geometry and is based on the finite volume method. Radiation transport is taken into account within the diffusion approximation. Realistic equation of state and opacities are implemented, allowing the study of a wide range of problems characteristic of stellar interiors. We describe in details the numerical method and various standard tests performed to validate the method. We present preliminary results devoted to the description of stellar convection. We first perform a local simulation of convection in the surface layers of a A-type star model. This simulation is used to test the ability of the code to address stellar conditions and to validate our results, since they can be compared to similar previous simulations based on explicit codes. We then present a global simulation of turbul...
Ahn, Hyung-Joon; Bang, Young-Seok; Kim, In-Goo; Kim, Hho-Jung; Lee, Byeong-Eun; Kwon, Soon-Bum
2002-07-01
The In-containment Refueling Water Storage Tank (IRWST) has the function of heat sink when steam is released from the pressurizer. The hydrodynamic behaviors occurring at the sparger are very complex because of the wide variety of operating conditions and the complex geometry. Hydrodynamic behavior when air is discharged through a sparger in a condensation pool is investigated using CFD techniques in the present study. The effect of pressure acting on the sparger header during both water and air discharge through the sparger is studied. In addition, pressure oscillation occurring during air discharge through the sparger is studied for a better understanding of mechanisms of air discharge and a better design of the IRWST, including sparger. (authors)
Santiago, Juan G.
focusing microfluidic mixer for protein folding Benjamin Ivorra, Juana L. Redondo, Juan G. Santiago, Pilar of a fast hydrodynamic focusing microfluidic mixer for protein folding Benjamin Ivorra,1,a) Juana L. Redondo
Cope, David M. (David Michael)
2012-01-01
Hydrodynamic flow visualization techniques of scaled hull forms and propellers are typically limited to isolating certain operating conditions in a tow tank, circulation tunnel, or large maneuvering basin. Although cost ...
M. Ruffert
1995-10-04
We investigate the hydrodynamics of three-dimensional classical Bondi-Hoyle accretion. A totally absorbing sphere of different sizes (1, 0.1 and 0.02 accretion radii) moves at different Mach numbers (0.6, 1.4, 3.0 and 10) relative to a homogeneous and slightly perturbed medium, which is taken to be an ideal, nearly isothermal, gas ($\\gamma=1.01$). The hydrodynamics is modeled by the ``Piecewise Parabolic Method'' (PPM). The resolution in the vicinity of the accretor is increased by multiply nesting several $32^3$-zone grids around the sphere, each finer grid being a factor of two smaller in zone size than the next coarser grid. grids. For small Mach numbers (0.6 and~1.4) the flow patterns tend towards a steady state, while in the case of supersonic flow (Mach~3 and~10) and small enough accretors (radius of~0.1 and~0.02 accretion radii), an unstable Mach cone develops, destroying axisymmetry. The shock cones in the supersonic models never clear the surface of the accretors (they are tail shocks, not bow shocks) and the opening angle is smaller (compared to models with larger $\\gamma$) especially for the highly supersonic models. The densities in the shock cone is larger for models with smaller $\\gamma$. The fluctuations of the accretion rates and flow structures are weaker than in the corresponding models with larger $\\gamma$. The hydrodynamic drag of all models with accretor sizes of 0.1~$R_{\\rm A}$ or smaller acts in an accelerating direction, while the gravitational drag is always decelerating and larger than the hydrodynamic drag (thus the net force is decelerating).
Radiative hydrodynamic modelling and observations of the X-class solar flare on 2011 March 9
Kennedy, Michael B; Allred, Joel C; Mathioudakis, Mihalis; Keenan, Francis P
2015-01-01
We investigated the response of the solar atmosphere to non-thermal electron beam heating using the radiative transfer and hydrodynamics modelling code RADYN. The temporal evolution of the parameters that describe the non-thermal electron energy distribution were derived from hard X-ray observations of a particular flare, and we compared the modelled and observed parameters. The evolution of the non-thermal electron beam parameters during the X1.5 solar flare on 2011 March 9 were obtained from analysis of RHESSI X-ray spectra. The RADYN flare model was allowed to evolve for 110 seconds, after which the electron beam heating was ended, and was then allowed to continue evolving for a further 300s. The modelled flare parameters were compared to the observed parameters determined from extreme-ultraviolet spectroscopy. The model produced a hotter and denser flare loop than that observed and also cooled more rapidly, suggesting that additional energy input in the decay phase of the flare is required. In the explosi...
Anderson, R W; Pember, R B; Elliot, N S
2000-09-26
A new method for the solution of the unsteady Euler equations has been developed. The method combines staggered grid Lagrangian techniques with structured local adaptive mesh refinement (AMR). This method is a precursor to a more general adaptive arbitrary Lagrangian Eulerian (ALE-AMR) algorithm under development, which will facilitate the solution of problems currently at and beyond the boundary of soluble problems by traditional ALE methods by focusing computational resources where they are required. Many of the core issues involved in the development of the ALE-AMR method hinge upon the integration of AMR with a Lagrange step, which is the focus of the work described here. The novel components of the method are mainly driven by the need to reconcile traditional AMR techniques, which are typically employed on stationary meshes with cell-centered quantities, with the staggered grids and grid motion employed by Lagrangian methods. These new algorithmic components are first developed in one dimension and are then generalized to two dimensions. Solutions of several model problems involving shock hydrodynamics are presented and discussed.
HYDRODYNAMICS OF CORE-COLLAPSE SUPERNOVAE AT THE TRANSITION TO EXPLOSION. I. SPHERICAL SYMMETRY
Fernandez, Rodrigo [Institute for Advanced Study, Einstein Drive, Princeton, NJ 08540 (United States)
2012-04-20
We study the transition to runaway expansion of an initially stalled core-collapse supernova shock. The neutrino luminosity, mass accretion rate, and neutrinospheric radius are all treated as free parameters. In spherical symmetry, this transition is mediated by a global non-adiabatic instability that develops on the advection time and reaches nonlinear amplitude. Here, we perform high-resolution, time-dependent hydrodynamic simulations of stalled supernova shocks with realistic microphysics to analyze this transition. We find that radial instability is a sufficient condition for runaway expansion if the neutrinospheric parameters do not vary with time and if heating by the accretion luminosity is neglected. For a given unstable mode, transition to runaway occurs when fluid in the gain region reaches positive specific energy. We find approximate instability criteria that accurately describe the behavior of the system over a wide region of parameter space. The threshold neutrino luminosities are in general different than the limiting value for a steady-state solution. We hypothesize that multidimensional explosions arise from the excitation of unstable large-scale modes of the turbulent background flow, at threshold luminosities that are lower than in the laminar case.
1995-08-01
On May 12, 1995, the U.S. Department of Energy (DOE) issued the draft Dual Axis Radiographic Hydrodynamic Test Facility Environmental Impact Statement (DARHT EIS) for review by the State of New Mexico, Indian Tribes, local governments, other Federal agencies, and the general public. DOE invited comments on the accuracy and adequacy of the draft EIS and any other matters pertaining to their environmental reviews. The formal comment period ran for 45 days, to June 26, 1995, although DOE indicated that late comments would be considered to the extent possible. As part of the public comment process, DOE held two public hearings in Los Alamos and Santa Fe, New Mexico, on May 31 and June 1, 1995. In addition, DOE made the draft classified supplement to the DARHT EIS available for review by appropriately cleared individuals with a need to know the classified information. Reviewers of the classified material included the State of New Mexico, the U.S. Environmental Protection Agency, the Department of Defense, and certain Indian Tribes. Volume 2 of the final DARHT EIS contains three chapters. Chapter 1 includes a collective summary of the comments received and DOE`s response. Chapter 2 contains the full text of the public comments on the draft DARHT EIS received by DOE. Chapter 3 contains DOE`s responses to the public comments and an indication as to how the comments were considered in the final EIS.
Dynamics of pebbles in the vicinity of a growing planetary embryo: hydro-dynamical simulations
Morbidelli, Alessandro
2012-01-01
Understanding the growth of the cores of giant planets is a difficult problem. Recently, Lambrechts and Johansen (2012; LJ12) proposed a new model in which the cores grow by the accretion of pebble-size objects, as the latter drift towards the star due to gas drag. Here, we investigate the dynamics of pebble-size objects in the vicinity of planetary embryos of 1 and 5 Earth masses and the resulting accretion rates. We use hydrodynamical simulations, in which the embryo influences the dynamics of the gas and the pebbles suffer gas drag according to the local gas density and velocities. The pebble dynamics in the vicinity of the planetary embryo is non-trivial, and it changes significantly with the pebble size. Nevertheless, the accretion rate of the embryo that we measure is within an order of magnitude of the rate estimated in LJ12 and tends to their value with increasing pebble-size. We conclude that the model by LJ12 has the potential to explain the rapid growth of giant planet cores. The actual accretion r...
L. Del Zanna; N. Bucciantini
2002-05-17
Multidimensional shock-capturing numerical schemes for special relativistic hydrodynamics (RHD) are computationally more expensive than their correspondent Euler versions, due to the nonlinear relations between conservative and primitive variables and to the consequent complexity of the Jacobian matrices (needed for the spectral decomposition in most of the approximate Riemann solvers of common use). Here an efficient and easy-to-implement three-dimensional (3-D) shock-capturing scheme for ideal RHD is presented. Based on the algorithms developed by P. Londrillo and L. Del Zanna ({\\em Astrophys. J.} 530, 508-524, 2000) for the non-relativistic magnetohydrodynamic (MHD) case, and having in mind its relativistic MHD extension (to appear in a forthcoming paper), the scheme uses high order (third) Convex Essentially Non-Oscillatory (CENO) finite difference interpolation routines and central-type averaged Riemann solvers, which do not make use of time-consuming characteristic decomposition. The scheme is very efficient and robust, and it gives results comparable to those obtained with more sophisticated algorithms, even in ultrarelativistic multidimensional test problems.
Chipman, V D
2011-09-20
Two-dimensional axisymmetric hydrodynamic models were developed using GEODYN to simulate the propagation of air blasts resulting from a series of high explosive detonations conducted at Kirtland Air Force Base in August and September of 2007. Dubbed Humble Redwood I (HR-1), these near-surface chemical high explosive detonations consisted of seven shots of varying height or depth of burst. Each shot was simulated numerically using GEODYN. An adaptive mesh refinement scheme based on air pressure gradients was employed such that the mesh refinement tracked the advancing shock front where sharp discontinuities existed in the state variables, but allowed the mesh to sufficiently relax behind the shock front for runtime efficiency. Comparisons of overpressure, sound speed, and positive phase impulse from the GEODYN simulations were made to the recorded data taken from each HR-1 shot. Where the detonations occurred above ground or were shallowly buried (no deeper than 1 m), the GEODYN model was able to simulate the sound speeds, peak overpressures, and positive phase impulses to within approximately 1%, 23%, and 6%, respectively, of the actual recorded data, supporting the use of numerical simulation of the air blast as a forensic tool in determining the yield of an otherwise unknown explosion.
Yanbiao Gan; Aiguo Xu; Guangcai Zhang; Sauro Succi
2015-05-11
A discrete Boltzmann model (DBM) is developed to investigate the hydrodynamic and thermodynamic non-equilibrium (TNE) effects in phase separation processes. The interparticle force drives changes and the gradient force, induced by gradients of macroscopic quantities, opposes them. In this paper, we investigate the interplay between them by providing detailed inspection of various non-equilibrium observables. Based on the TNE features, we define a TNE strength which roughly estimates the deviation amplitude from the thermodynamic equilibrium. The time evolution of the TNE intensity provides a convenient and efficient physical criterion to discriminate the stages of the spinodal decomposition and domain growth. Via the DBM simulation and this criterion, we quantitatively study the effects of latent heat and surface tension on phase separation. It is found that, the TNE strength attains its maximum at the end of the spinodal decomposition stage, and it decreases when the latent heat increases from zero. The surface tension effects are threefold, to prolong the duration of the spinodal decomposition stage, decrease the maximum TNE intensity, and accelerate the speed of the domain growth stage.
Three-dimensional hydrodynamic simulations of the combustion of a neutron star into a quark star
Matthias Herzog; Friedrich K. Roepke
2011-09-02
We present three-dimensional numerical simulations of turbulent combustion converting a neutron star into a quark star. Hadronic matter, described by a micro-physical finite-temperature equation of state, is converted into strange quark matter. We assume this phase, represented by a bag-model equation of state, to be absolutely stable. Following the example of thermonuclear burning in white dwarfs leading to Type Ia supernovae, we treat the conversion process as a potentially turbulent deflagration. Solving the non-relativistic Euler equations using established numerical methods we conduct large eddy simulations including an elaborate subgrid scale model, while the propagation of the conversion front is modeled with a level-set method. Our results show that for large parts of the parameter space the conversion becomes turbulent and therefore significantly faster than in the laminar case. Despite assuming absolutely stable strange quark matter, in our hydrodynamic approximation an outer layer remains in the hadronic phase, because the conversion front stops when it reaches conditions under which the combustion is no longer exothermic.
Impacts of rotation on three-dimensional hydrodynamics of core-collapse supernovae
Nakamura, Ko; Kuroda, Takami; Kotake, Kei [Division of Theoretical Astronomy, National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588 (Japan); Takiwaki, Tomoya [Center for Computational Astrophysics, National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588 (Japan)
2014-09-20
We perform a series of simplified numerical experiments to explore how rotation impacts the three-dimensional (3D) hydrodynamics of core-collapse supernovae. For our systematic study, we employ a light-bulb scheme to trigger explosions and a three-flavor neutrino leakage scheme to treat deleptonization effects and neutrino losses from the proto-neutron-star interior. Using a 15 M {sub ?} progenitor, we compute 30 models in 3D with a wide variety of initial angular momentum and light-bulb neutrino luminosity. We find that the rotation can help the onset of neutrino-driven explosions for the models in which the initial angular momentum is matched to that obtained in recent stellar evolutionary calculations (?0.3-3 rad s{sup –1} at the center). For the models with larger initial angular momentum, the shock surface deforms to be more oblate due to larger centrifugal force. This not only makes the gain region more concentrated around the equatorial plane, but also makes the mass larger in the gain region. As a result, buoyant bubbles tend to be coherently formed and rise in the equatorial region, which pushes the revived shock toward ever larger radii until a global explosion is triggered. We find that these are the main reasons that the preferred direction of the explosion in 3D rotating models is often perpendicular to the spin axis, which is in sharp contrast to the polar explosions around the axis that were obtained in previous two-dimensional simulations.
V. S. Imshennik; K. V. Manukovskii
2004-11-16
We numerically solved the two-dimensional axisymmetric hydrodynamic problem of the explosion of a low-mass neutron star in a circular orbit. In the initial conditions, we assumed a nonuniform density distribution in the space surrounding the collapsed iron core in the form of a stationary toroidal atmosphere that was previously predicted analytically and computed numerically. The con?guration of the exploded neutron star itself was modeled by a torus with a circular cross section whose central line almost coincided with its circular orbit. Using an equation of state for the stellar matter and the toroidal atmosphere in which the nuclear statistical equilibrium conditions were satisfied, we performed a series of numerical calculations that showed the propagation of a strong divergent shock wave with a total energy of 0.2x10^51 erg at initial explosion energy release of 1.0x10^51 erg. In our calculations, we rigorously took into account the gravitational interaction, including the attraction from a higher-mass (1.9M_solar) neutron star located at the coordinate origin, in accordance with the rotational explosion mechanism for collapsing supernovae.W e compared in detail our results with previous similar results of asymmetric supernova explosion simulations and concluded that we found a lower limit for the total explosion energy.
Sun, Xuefei; Kelly, Ryan T.; Danielson, William F.; Agrawal, Nitin; Tang, Keqi; Smith, Richard D.
2011-04-26
A novel hydrodynamic injector that is directly controlled by a pneumatic valve has been developed for reproducible microchip capillary electrophoresis (CE) separations. The poly(dimethylsiloxane) (PDMS) devices used for evaluation comprise a separation channel, a side channel for sample introduction, and a pneumatic valve aligned at the intersection of the channels. A low pressure (? 3 psi) applied to the sample reservoir is sufficient to drive sample into the separation channel. The rapidly actuated pneumatic valve enables injection of discrete sample plugs as small as ~100 pL for CE separation. The injection volume can be easily controlled by adjusting the intersection geometry, the solution back pressure and the valve actuation time. Sample injection could be reliably operated at different frequencies (< 0.1 Hz to >2 Hz) with good reproducibility (peak height relative standard deviation ? 3.6%) and no sampling biases associated with the conventional electrokinetic injections. The separation channel was dynamically coated with a cationic polymer, and FITC-labeled amino acids were employed to evaluate the CE separation. Highly efficient (? 7.0 × 103 theoretical plates for the ~2.4 cm long channel) and reproducible CE separations were obtained. The demonstrated method has numerous advantages compared with the conventional techniques, including repeatable and unbiased injections, no sample waste, high duty cycle, controllable injected sample volume, and fewer electrodes with no need for voltage switching. The prospects of implementing this injection method for coupling multidimensional separations, for multiplexing CE separations and for sample-limited bioanalyses are discussed.
Kuznetsov, E A
2015-01-01
Statistical characteristics of the Kraichnan direct cascade for two-dimensional hydrodynamic turbulence are numerically studied (with spatial resolution $8192\\times 8192$) in the presence of pumping and viscous-like damping. It is shown that quasi-shocks of vorticity and their Fourier partnerships in the form of jets introduce an essential influence in turbulence leading to strong angular dependencies for correlation functions. The energy distribution as a function of modulus $k$ for each angle in the inertial interval has the Kraichnan behavior, $\\sim k^{-4}$, and simultaneously a strong dependence on angles. However, angle average provides with a high accuracy the Kraichnan turbulence spectrum $E_k=C_K\\eta^{2/3} k^{-3}$ where $\\eta$ is enstrophy flux and the Kraichnan constant $C_K\\simeq 1.3$, in correspondence with the previous simulations. Familiar situation takes place for third-order velocity structure function $S_3^L$ which, as for the isotropic turbulence, gives the same scaling with respect to separa...
E. A. Kuznetsov; E. V. Sereshchenko
2015-10-30
Statistical characteristics of the Kraichnan direct cascade for two-dimensional hydrodynamic turbulence are numerically studied (with spatial resolution $8192\\times 8192$) in the presence of pumping and viscous-like damping. It is shown that quasi-shocks of vorticity and their Fourier partnerships in the form of jets introduce an essential influence in turbulence leading to strong angular dependencies for correlation functions. The energy distribution as a function of modulus $k$ for each angle in the inertial interval has the Kraichnan behavior, $\\sim k^{-4}$, and simultaneously a strong dependence on angles. However, angle average provides with a high accuracy the Kraichnan turbulence spectrum $E_k=C_K\\eta^{2/3} k^{-3}$ where $\\eta$ is enstrophy flux and the Kraichnan constant $C_K\\simeq 1.3$, in correspondence with the previous simulations. Familiar situation takes place for third-order velocity structure function $S_3^L$ which, as for the isotropic turbulence, gives the same scaling with respect to separation length $R$ and $\\eta$, $S_3^L=C_3\\eta R^3$, but the mean over angles and time $\\bar {C_3}$ differs from its isotropic value.
Local Radiation Hydrodynamic Simulations of Massive Star Envelopes at the Iron Opacity Peak
Jiang, Yan-Fei; Bildsten, Lars; Quataert, Eliot; Blaes, Omer
2015-01-01
We perform three dimensional radiation hydrodynamic simulations of the structure and dynamics of radiation dominated envelopes of massive stars at the location of the iron opacity peak. One dimensional hydrostatic calculations predict an unstable density inversion at this location, whereas our simulations reveal a complex interplay of convective and radiative transport whose behavior depends on the ratio of the photon diffusion time to the dynamical time. The latter is set by the ratio of the optical depth per pressure scale height, $\\tau_0$, to $\\tau_c=c/c_g$, where $c_g \\approx$ 50 km/s is the isothermal sound speed in the gas alone. When $\\tau_0 \\gg \\tau_c$, convection reduces the radiation acceleration and removes the density inversion. The turbulent energy transport in the simulations agrees with mixing length theory and provides its first numerical calibration in the radiation dominated regime. When $\\tau_0 \\ll \\tau_c$, convection becomes inefficient and the turbulent energy transport is negligible. The...
Bu, De-Fu; Gan, Zhao-Ming; Yang, Xiao-hong
2015-01-01
In previous works, it has been shown that strong winds exist in hot accretion flows around black holes. Those works focus only on the region close to the black hole thus it is unknown whether or where the wind production stops at large radii. In this paper, we investigate this problem based on hydrodynamical numerical simulations. For this aim, we have taken into account the gravity of both the central black hole and the nuclear star clusters. When calculating the latter, we assume that the velocity dispersion of stars is a constant and the gravitational potential of the nuclear star cluster $\\propto \\sigma^2 \\ln (r)$, where $\\sigma$ is the velocity dispersion of stars and $r$ is the distance from the center of the galaxy. Different from previous works, we focus on the region where the gravitational potential is dominated by the star cluster. We find that, same as the accretion flow at small radii, the mass inflow rate decreases inward and the flow is convectively unstable. However, trajectory analysis has sh...
THE GENERAL RELATIVISTIC EQUATIONS OF RADIATION HYDRODYNAMICS IN THE VISCOUS LIMIT
Coughlin, Eric R.; Begelman, Mitchell C. E-mail: mitch@jila.colorado.edu
2014-12-20
We present an analysis of the general relativistic Boltzmann equation for radiation, appropriate to the case where particles and photons interact through Thomson scattering, and derive the radiation energy-momentum tensor in the diffusion limit with viscous terms included. Contrary to relativistic generalizations of the viscous stress tensor that appear in the literature, we find that the stress tensor should contain a correction to the comoving energy density proportional to the divergence of the four-velocity, as well as a finite bulk viscosity. These modifications are consistent with the framework of radiation hydrodynamics in the limit of large optical depth, and do not depend on thermodynamic arguments such as the assignment of a temperature to the zeroth-order photon distribution. We perform a perturbation analysis on our equations and demonstrate that as long as the wave numbers do not probe scales smaller than the mean free path of the radiation, the viscosity contributes only decaying, i.e., stable, corrections to the dispersion relations. The astrophysical applications of our equations, including jets launched from super-Eddington tidal disruption events and those from collapsars, are discussed and will be considered further in future papers.
Dubus, Guillaume; Fromang, Sébastien
2015-01-01
Detailed modeling of the high-energy emission from gamma-ray binaries has been propounded as a path to pulsar wind physics. Fulfilling this ambition requires a coherent model of the flow and its emission in the region where the pulsar wind interacts with the stellar wind of its companion. We developed a code that follows the evolution and emission of electrons in the shocked pulsar wind based on inputs from a relativistic hydrodynamical simulation. The code is used to model the well-documented spectral energy distribution and orbital modulations from LS 5039. The pulsar wind is fully confined by a bow shock and a back shock. The particles are distributed into a narrow Maxwellian, emitting mostly GeV photons, and a power law radiating very efficiently over a broad energy range from X-rays to TeV gamma rays. Most of the emission arises from the apex of the bow shock. Doppler boosting shapes the X-ray and VHE lightcurves, constraining the system inclination to $i\\approx 35^{\\rm o}$. There is a tension between th...
Photospheric Emission of Collapsar Jet in 3D Relativistic Radiation Hydrodynamical Simulation
Ito, Hirotaka; Nagataki, Shigehiro; Warren, Donald C; Barkov, Maxim V
2015-01-01
We explore the photospheric emission from a relativistic jet breaking out from a massive stellar envelope based on relativistic hydrodynamical simulations and post-process radiation transfer calculations in three dimensions (3D). To investigate the impact of 3D dynamics on the emission, two models of injection conditions are considered for the jet at the center of the progenitor star: one with periodic precession and another without precession. We show that structures developed within the jet due to the interaction with the stellar envelope, as well as due to the precession, have a significant imprint on the resulting emission. Particularly, we find that the signature of precession activity by the central engine is not smeared out and can be directly observed in the light curve as a periodic signal. We also show non-thermal features that can account for observations of gamma-ray bursts are produced in the resulting spectra, even though only thermal photons are injected initially and the effect of non-thermal ...
da Costa, Fatima Rubio; Petrosian, Vahé; Dalda, Alberto Sainz; Liu, Wei
2014-01-01
Solar flares involve impulsive energy release, which results in enhanced radiation in a broad spectral and at a wide height range. In particular, line emission from the chromosphere (lower atmosphere) can provide critical diagnostics of plasma heating processes. Thus, a direct comparison between high-resolution spectroscopic observations and advanced numerical modeling results can be extremely valuable, but has not been attempted so far. We present in this paper such a self-consistent investigation of an M3.0 flare observed by the Dunn Solar Telescope's (DST) Interferometric Bi-dimensional Spectrometer (IBIS) on 2011 September 24 that we have modeled with the radiative hydrodynamic code RADYN (Carlsson & Stein 1992, 1997; Abbett & Hawley 1999; Allred et al. 2005). We obtained images and spectra of the flaring region with IBIS in H$\\alpha$ 6563 \\AA\\ and Ca II 8542 \\AA, and with the Reuven Ramaty High Energy Solar Spectroscope Imager (RHESSI) in X-rays. The latter was used to infer the non-thermal elect...
Hydrodynamic models for slurry bubble column reactors. Sixth technical progress report
Gidaspow, D.
1996-01-01
The objective of this investigation is to convert the gas-solid-liquid fluidization model into a predictive design model. The IIT hydrodynamic model computes the phase velocities and the volume fractions of gas, liquid and particulate phases. Model verification involves a comparison of these computed velocities and volume fractions to experimental values. This report presents measurements of granular temperature of Air Products catalyst. The report is in the form of a preliminary paper, entitled ``Dynamics of Liquid-Solid Fluidized Beds with Small Catalyst Particles.`` The principal results are as follows: (1) For the liquid-solid system the granular temperature is much smaller than for a corresponding gas-solid system. This may be due to the larger viscosity of the liquid in comparison to air. (2) The collisional viscosity of the catalyst is correspondingly much smaller than that of catalyst particles in the air. (3) The dominant frequency of density oscillations is near two Hertz, as expected for a gas-solid fluidized bed. There exists a link between this low frequency and the high frequency of catalyst particle oscillations. The Air Products fluidized bed reactor is designed to produce methanol and synthetic fuels from synthesis gas.
HEAVY DUST OBSCURATION OF z = 7 GALAXIES IN A COSMOLOGICAL HYDRODYNAMIC SIMULATION
Kimm, Taysun; Cen, Renyue
2013-10-10
Hubble Space Telescope observations with the Wide Field Camera 3/Infrared reveal that galaxies at z ? 7 have very blue ultraviolet (UV) colors, consistent with these systems being dominated by young stellar populations with moderate or little attenuation by dust. We investigate UV and optical properties of the high-z galaxies in the standard cold dark matter model using a high-resolution adaptive mesh refinement cosmological hydrodynamic simulation. For this purpose, we perform panchromatic three-dimensional dust radiative transfer calculations on 198 galaxies of stellar mass 5 × 10{sup 8}-3 × 10{sup 10} M{sub ?} with three parameters: the dust-to-metal ratio, the extinction curve, and the fraction of directly escaped light from stars (f{sub esc}). Our stellar mass function is found to be in broad agreement with Gonzalez et al., independent of these parameters. We find that our heavily dust-attenuated galaxies (A{sub V} ? 1.8) can also reasonably match modest UV-optical colors, blue UV slopes, as well as UV luminosity functions, provided that a significant fraction (?10%) of light directly escapes from them. The observed UV slope and scatter are better explained with a Small-Magellanic-Cloud-type extinction curve, whereas a Milky-Way-type curve also predicts blue UV colors due to the 2175 Å bump. We expect that upcoming observations by the Atacama Large Millimeter/submillimeter Array will be able to test this heavily obscured model.
Sekiguchi, Yuichiro; Kyutoku, Koutarou; Shibata, Masaru
2015-01-01
We perform radiation-hydrodynamics simulations of binary neutron star mergers in numerical relativity on the Japanese "K" supercomputer, taking into account neutrino cooling and heating by an updated leakage-plus-transfer scheme for the first time. Neutron stars are modeled by three modern finite-temperature equations of state (EOS) developed by Hempel and his collaborators. We find that the electron fraction has a broad distribution due to the weak processes and shock heating. The properties of the ejecta such as total mass, average electron fraction, and thermal energy depend strongly on the EOS. Only for a soft EOS (the so-called SFHo), the ejecta mass exceeds $0.01M_{\\odot}$. In this case, the electron fraction has a broad distribution which is well-suited for the production of the solar-like $r$-process abundance. For the other stiff EOS (DD2 and TM1), for which a long-lived massive neutron star is formed after the merger, the ejecta mass is smaller than $0.01M_{\\odot}$, although broad electron-fraction ...
Center-to-Limb Variation of Solar 3-D Hydrodynamical Simulations
L. Koesterke; C. Allende Prieto; D. L. Lambert
2008-02-15
We examine closely the solar Center-to-Limb variation of continua and lines and compare observations with predictions from both a 3-D hydrodynamic simulation of the solar surface (provided by M. Asplund and collaborators) and 1-D model atmospheres. Intensities from the 3-D time series are derived by means of the new synthesis code ASSET, which overcomes limitations of previously available codes by including a consistent treatment of scattering and allowing for arbitrarily complex line and continuum opacities. In the continuum, we find very similar discrepancies between synthesis and observation for both types of model atmospheres. This is in contrast to previous studies that used a ``horizontally'' and time averaged representation of the 3-D model and found a significantly larger disagreement with observations. The presence of temperature and velocity fields in the 3-D simulation provides a significant advantage when it comes to reproduce solar spectral line shapes. Nonetheless, a comparison of observed and synthetic equivalent widths reveals that the 3-D model also predicts more uniform abundances as a function of position angle on the disk. We conclude that the 3-D simulation provides not only a more realistic description of the gas dynamics, but, despite its simplified treatment of the radiation transport, it also predicts reasonably well the observed Center-to-Limb variation, which is indicative of a thermal structure free from significant systematic errors.
Relativistic Hydrodynamic Flows Using Spatial and Temporal Adaptive Structured Mesh Refinement
Peng Wang; Tom Abel; Weiqun Zhang
2007-12-31
Astrophysical relativistic flow problems require high resolution three-dimensional numerical simulations. In this paper, we describe a new parallel three-dimensional code for simulations of special relativistic hydrodynamics (SRHD) using both spatially and temporally structured adaptive mesh refinement (AMR). We used the method of lines to discretize the SRHD equations spatially and a total variation diminishing (TVD) Runge-Kutta scheme for time integration. For spatial reconstruction, we have implemented piecewise linear method (PLM), piecewise parabolic method (PPM), third order convex essentially non-oscillatory (CENO) and third and fifth order weighted essentially non-oscillatory (WENO) schemes. Flux is computed using either direct flux reconstruction or approximate Riemann solvers including HLL, modified Marquina flux, local Lax-Friedrichs flux formulas and HLLC. The AMR part of the code is built on top of the cosmological Eulerian AMR code {\\sl enzo}. We discuss the coupling of the AMR framework with the relativistic solvers. Via various test problems, we emphasize the importance of resolution studies in relativistic flow simulations because extremely high resolution is required especially when shear flows are present in the problem. We also present the results of two 3d simulations of astrophysical jets: AGN jets and GRB jets. Resolution study of those two cases further highlights the need of high resolutions to calculate accurately relativistic flow problems.
Smolt Responses to Hydrodynamic Conditions in Forebay Flow Nets of Surface Flow Outlets, 2007
Johnson, Gary E.; Richmond, Marshall C.; Hedgepeth, J. B.; Ploskey, Gene R.; Anderson, Michael G.; Deng, Zhiqun; Khan, Fenton; Mueller, Robert P.; Rakowski, Cynthia L.; Sather, Nichole K.; Serkowski, John A.; Steinbeck, John R.
2009-04-01
This study provides information on juvenile salmonid behaviors at McNary and The Dalles dams that can be used by the USACE, fisheries resource managers, and others to support decisions on long-term measures to enhance fish passage. We researched smolt movements and ambient hydrodynamic conditions using a new approach combining simultaneous acoustic Doppler current profiler (ADCP) and acoustic imaging device (AID) measurements at surface flow outlets (SFO) at McNary and The Dalles dams on the Columbia River during spring and summer 2007. Because swimming effort vectors could be computed from the simultaneous fish and flow data, fish behavior could be categorized as passive, swimming against the flow (positively rheotactic), and swimming with the flow (negatively rheotactic). We present bivariate relationships to provide insight into fish responses to particular hydraulic variables that engineers might consider during SFO design. The data indicate potential for this empirical approach of simultaneous water/fish measurements to lead to SFO design guidelines in the future.
Hydrodynamic Models of Line-Driven Accretion Disk Winds II: Adiabatic Winds from Nonisothermal Disks
Nicolas Antonio Pereyra; Timothy R. Kallman; John M. Blondin
2000-11-03
We present here numerical hydrodynamic simulations of line-driven accretion disk winds in cataclysmic variable systems. We calculate wind mass-loss rate, terminal velocities, and line profiles for CIV (1550 A) for various viewing angles. The models are 2.5-dimensional, include an energy balance condition, and calculate the radiation field as a function of position near an optically thick accretion disk. The model results show that centrifugal forces produce collisions of streamlines in the disk wind which in turn generate an enhanced density region, underlining the necessity of two dimensional calculations where these forces may be represented. For disk luminosity Ldisk = Lsun, white dwarf mass Mwd = 0.6 Msun, and white dwarf radii Rwd = 0.01 Rsun, we obtain a wind mass-loss rate of dMwind/dt = 8.0E-12 Msun/yr, and a terminal velocity of ~3000 km/s. The line profiles we obtain are consistent with observations in their general form, in particular in the maximum absorption at roughly half the terminal velocity for the blue-shifted component, in the magnitudes of the wind velocities implied by the absorption components, in the FWHM of the emission components, and in the strong dependence in inclination angle.
Hydrodynamic Models of Line-Driven Accretion Disk Winds II Adiabatic Winds from Nonisothermal Disks
Pereyra, N A; Blondin, J M; Pereyra, Nicolas Antonio; Kallman, Timothy R.; Blondin, John M.
2000-01-01
We present here numerical hydrodynamic simulations of line-driven accretion disk winds in cataclysmic variable systems. We calculate wind mass-loss rate, terminal velocities, and line profiles for CIV (1550 A) for various viewing angles. The models are 2.5-dimensional, include an energy balance condition, and calculate the radiation field as a function of position near an optically thick accretion disk. The model results show that centrifugal forces produce collisions of streamlines in the disk wind which in turn generate an enhanced density region, underlining the necessity of two dimensional calculations where these forces may be represented. For disk luminosity Ldisk = Lsun, white dwarf mass Mwd = 0.6 Msun, and white dwarf radii Rwd = 0.01 Rsun, we obtain a wind mass-loss rate of dMwind/dt = 8.0E-12 Msun/yr, and a terminal velocity of ~3000 km/s. The line profiles we obtain are consistent with observations in their general form, in particular in the maximum absorption at roughly half the terminal velocity ...
Linearized fluid/gravity correspondence: from shear viscosity to all order hydrodynamics
Yanyan Bu; Michael Lublinsky
2015-03-09
In ref. \\cite{1406.7222}, we reported a construction of all order linearized fluid dynamics with strongly coupled $\\mathcal{N}=4$ super-Yang-Mills theory as underlying microscopic description. The linearized fluid/gravity correspondence makes it possible to resum all order derivative terms in the fluid stress tensor. Dissipative effects are fully encoded by the shear term and a new one, emerging starting from third order in hydrodynamic derivative expansion. In this work, we provide all computational details omitted in \\cite{1406.7222} and present additional results. We derive closed-form linear holographic RG flow-type equations for momenta-dependent transport coefficient functions. Generalized Navier-Stokes equations are shown to emerge from the constraint components of the bulk Einstein equations. We perturbatively solve the RG equations for the viscosity functions, up to third order in derivative expansion, and up to this order compute spectrum of small fluctuations. Finally, we solve the RG equations numerically, thus accounting for all order derivative terms in the boundary stress tensor.
Verification of coronal loop diagnostics using realistic three-dimensional hydrodynamic models
Winebarger, Amy R.; Lionello, Roberto; Linker, Jon A.; Miki?, Zoran; Mok, Yung E-mail: lionel@predsci.com E-mail: mikicz@predsci.com
2014-11-10
Many different techniques have been used to characterize the plasma in the solar corona: density-sensitive spectral line ratios are used to infer the density, the evolution of coronal structures in different passbands is used to infer the temperature evolution, and the simultaneous intensities measured in multiple passbands are used to determine the emission measure distributions. All these analysis techniques assume that the intensity of the structures can be isolated through background subtraction. In this paper, we use simulated observations from a three-dimensional hydrodynamic simulation of a coronal active region to verify these diagnostics. The density and temperature from the simulation are used to generate images in several passbands and spectral lines. We identify loop structures in the simulated images and calculate the background. We then determine the density, temperature, and emission measure distribution as a function of time from the observations and compare these with the true temperature and density of the loop. We find that the overall characteristics of the temperature, density, and emission measure are recovered by the analysis methods, but the details are not. For instance, the emission measure curves calculated from the simulated observations are much broader than the true emission measure distribution, though the average temperature evolution is similar. These differences are due, in part, to a limitation of the analysis methods, but also to inadequate background subtraction.
Zhang, Ying-Ying; An, Sheng-Bai; Song, Yuan-Hong Wang, You-Nian; Kang, Naijing; Miškovi?, Z. L.
2014-10-15
We study the wake effect in the induced potential and the stopping power due to plasmon excitation in a metal slab by a point charge moving inside the slab. Nonlocal effects in the response of the electron gas in the metal are described by a quantum hydrodynamic model, where the equation of electronic motion contains both a quantum pressure term and a gradient correction from the Bohm quantum potential, resulting in a fourth-order differential equation for the perturbed electron density. Thus, besides using the condition that the normal component of the electron velocity should vanish at the impenetrable boundary of the metal, a consistent inclusion of the gradient correction is shown to introduce two possibilities for an additional boundary condition for the perturbed electron density. We show that using two different sets of boundary conditions only gives rise to differences in the wake potential at large distances behind the charged particle. On the other hand, the gradient correction in the quantum hydrodynamic model is seen to cause a reduction in the depth of the potential well closest to the particle, and a reduction of its stopping power. Even for a particle moving in the center of the slab, we observe nonlocal effects in the induced potential and the stopping power due to reduction of the slab thickness, which arise from the gradient correction in the quantum hydrodynamic model.
Kordilla, Jannes; Pan, Wenxiao; Tartakovsky, Alexandre M.
2014-12-14
We propose a novel Smoothed Particle Hydrodynamics (SPH) discretization of the fully-coupled Landau-Lifshitz-Navier-Stokes (LLNS) and advection-diffusion equations. The accuracy of the SPH solution of the LLNS equations is demonstrated by comparing the scaling of velocity variance and self-diffusion coefficient with kinetic temperature and particle mass obtained from the SPH simulations and analytical solutions. The spatial covariance of pressure and velocity fluctuations are found to be in a good agreement with theoretical models. To validate the accuracy of the SPH method for the coupled LLNS and advection-diffusion equations, we simulate the interface between two miscible fluids. We study the formation of the so-called giant fluctuations of the front between light and heavy fluids with and without gravity, where the light fluid lays on the top of the heavy fluid. We find that the power spectra of the simulated concentration field is in good agreement with the experiments and analytical solutions. In the absence of gravity the the power spectra decays as the power -4 of the wave number except for small wave numbers which diverge from this power law behavior due to the effect of finite domain size. Gravity suppresses the fluctuations resulting in the much weaker dependence of the power spectra on the wave number. Finally the model is used to study the effect of thermal fluctuation on the Rayleigh-Taylor instability, an unstable dynamics of the front between a heavy fluid overlying a light fluid. The front dynamics is shown to agree well with the analytical solutions.
An Open-Source Neutrino Radiation Hydrodynamics Code for Core-Collapse Supernovae
Evan O'Connor
2015-10-01
We present an open-source update to the spherically-symmetric, general-relativistic hydrodynamics, core-collapse supernova (CCSN) code GR1D (O'Connor & Ott, 2010, CQG, 27, 114103). The source code is available at http://www.GR1Dcode.org. We extend its capabilities to include a general relativistic treatment of neutrino transport based on the moment formalisms of Shibata et al., 2011, PTP, 125, 1255 and Cardall et al., 2013, PRD, 87 103004. We pay special attention to implementing and testing numerical methods and approximations that lessen the computational demand of the transport scheme by removing the need to invert large matrices. This is especially important for the implementation and development of moment-like transport methods in two and three dimensions. A critical component of neutrino transport calculations are the neutrino-matter interaction coefficients that describe the production, absorption, scattering, and annihilation of neutrinos. In this article we also describe our open-source, neutrino interaction library NuLib (available at http://www.nulib.org). We believe that an open-source approach to describing these interactions is one of the major steps needed to progress towards robust models of CCSNe and robust predictions of the neutrino signal. We show, via comparisons to full Boltzmann neutrino transport simulations of CCSNe, that our neutrino transport code performs remarkably well. Furthermore, we show that the methods and approximations we employ to increase efficiency do not decrease the fidelity of our results. We also test the ability of our general relativistic transport code to model failed CCSN by evolving a 40 solar-mass progenitor to the onset of collapse to a black hole.
Experimental study of the hydrodynamics and cluster formation in a Circulating Fluidized Bed
Gautam, M.; Johnson, E.
1991-01-01
A novel non-invasive gas-solid flow measuring technique being developed and tested for studying the hydrodynamics inside the riser of a Circulating Fluidized Bed (CFB). First of the two aims of the overall program, namely, design, development and testing of the technique to characterize the particle and gas velocities in two-phase flows was accomplished in the past year. The fringe-model'' laser Doppler anemometry concept has been modified and extended by using particles coated with a fluorescent dye and introducing a narrow band pass filter in the receiving optics. The technique permits optical discrimination between the scattered light (laser wavelength from undyed particles) and the fluorescence emission (longer wavelength). Results from extensive testing of various dye-solvent combinations, counter processor settings, signal-to noise optimization and subsequent flow measurements in the test section have shown that the technique can effectively discriminate between two classes of particles--the smaller seed particles for the gas phase data and the larger bed particles. Use of a two-watt Argon-Ion laser assisted in the non-intrusive probing of the gas-solid flow and in enhancing the signal-to-noise ratio. An uncertainty analysis of LDA measurements is presented. Design of the cold flow CFB model, presently under fabrication, is outlined in this report. The Plexiglas CFB model will be employed for the riser core-annular flow studies using the fluorescence-emission based laser-Doppler anemometry. The results from this study will present a unique detailed description of the complex gas-solid behavior in the CFB riser.
Hydrodynamic Models of Type I X-Ray Bursts: Metallicity Effects
Jordi Jose; Fermin Moreno; Anuj Parikh; Christian Iliadis
2010-05-26
Type I X-ray bursts are thermonuclear stellar explosions driven by charged-particle reactions. In the regime for combined H/He-ignition, the main nuclear flow is dominated by the rp-process (rapid proton-captures and beta+ decays), the 3 alpha-reaction, and the alpha-p-process (a suite of (alpha,p) and (p,gamma) reactions). The main flow is expected to proceed away from the valley of stability, eventually reaching the proton drip-line beyond A = 38. Detailed analysis of the relevant reactions along the main path has only been scarcely addressed, mainly in the context of parameterized one-zone models. In this paper, we present a detailed study of the nucleosynthesis and nuclear processes powering type I X-ray bursts. The reported 11 bursts have been computed by means of a spherically symmetric (1D), Lagrangian, hydrodynamic code, linked to a nuclear reaction network that contains 325 isotopes (from 1H to 107Te), and 1392 nuclear processes. These evolutionary sequences, followed from the onset of accretion up to the explosion and expansion stages, have been performed for 2 different metallicities to explore the dependence between the extension of the main nuclear flow and the initial metal content. We carefully analyze the dominant reactions and the products of nucleosynthesis, together with the the physical parameters that determine the light curve (including recurrence times, ratios between persistent and burst luminosities, or the extent of the envelope expansion). Results are in qualitative agreement with the observed properties of some well-studied bursting sources. Leakage from the predicted SbSnTe-cycle cannot be discarded in some of our models. Production of 12C (and implications for the mechanism that powers superbursts), light p-nuclei, and the amount of H left over after the bursting episodes will also be discussed.
STAR FORMATION AND FEEDBACK IN SMOOTHED PARTICLE HYDRODYNAMIC SIMULATIONS. II. RESOLUTION EFFECTS
Christensen, Charlotte R.; Quinn, Thomas; Bellovary, Jillian [Department of Astronomy, University of Washington, Box 351580, Seattle WA 98195 (United States); Stinson, Gregory [Jeremiah Horrocks Institute, University of Central Lancashire, Preston, PR1 2HE (United Kingdom); Wadsley, James, E-mail: christensen@astro.washington.ed [Department of Physics and Astronomy, ABB-241, McMaster University, 1280 Main St. W, Hamilton, ON, L8S 4M1 (Canada)
2010-07-01
We examine the effect of mass and force resolution on a specific star formation (SF) recipe using a set of N-body/smooth particle hydrodynamic simulations of isolated galaxies. Our simulations span halo masses from 10{sup 9} to 10{sup 13} M{sub sun}, more than 4 orders of magnitude in mass resolution, and 2 orders of magnitude in the gravitational softening length, {epsilon}, representing the force resolution. We examine the total global SF rate, the SF history, and the quantity of stellar feedback and compare the disk structure of the galaxies. Based on our analysis, we recommend using at least 10{sup 4} particles each for the dark matter (DM) and gas component and a force resolution of {epsilon} {approx} 10{sup -3} R{sub vir} when studying global SF and feedback. When the spatial distribution of stars is important, the number of gas and DM particles must be increased to at least 10{sup 5} of each. Low-mass resolution simulations with fixed softening lengths show particularly weak stellar disks due to two-body heating. While decreasing spatial resolution in low-mass resolution simulations limits two-body effects, density and potential gradients cannot be sustained. Regardless of the softening, low-mass resolution simulations contain fewer high density regions where SF may occur. Galaxies of approximately 10{sup 10} M{sub sun} display unique sensitivity to both mass and force resolution. This mass of galaxy has a shallow potential and is on the verge of forming a disk. The combination of these factors gives this galaxy the potential for strong gas outflows driven by supernova feedback and makes it particularly sensitive to any changes to the simulation parameters.
Andronov, V.A.; Zhidov, I.G.; Meskov, E.E.; Nevmerzhitskii, N.V.; Nikiforov, V.V.; Razin, A.N.; Rogatchev, V.G.; Tolshmyakov, A.I.; Yanilkin, Y.V.
1994-12-31
The report presents the basic results of some calculations, theoretical and experimental efforts in the study of Rayleigh-Taylor, Kelvin-Helmholtz, Richtmyer-Meshkov instabilities and the turbulent mixing which is caused by their evolution. Since the late forties the VNIIEF has been conducting these investigations. This report is based on the data which were published in different times in Russian and foreign journals. The first part of the report deals with calculations an theoretical techniques for the description of hydrodynamic instabilities applied currently, as well as with the results of several individual problems and their comparison with the experiment. These methods can be divided into two types: direct numerical simulation methods and phenomenological methods. The first type includes the regular 2D and 3D gasdynamical techniques as well as the techniques based on small perturbation approximation and on incompressible liquid approximation. The second type comprises the techniques based on various phenomenological turbulence models. The second part of the report describes the experimental methods and cites the experimental results of Rayleigh-Taylor and Richtmyer-Meskov instability studies as well as of turbulent mixing. The applied methods were based on thin-film gaseous models, on jelly models and liquid layer models. The research was done for plane and cylindrical geometries. As drivers, the shock tubes of different designs were used as well as gaseous explosive mixtures, compressed air and electric wire explosions. The experimental results were applied in calculational-theoretical technique calibrations. The authors did not aim at covering all VNIIEF research done in this field of science. To a great extent the choice of the material depended on the personal contribution of the author in these studies.
Hydrodynamic Theory for Reverse Brazil Nut Segregation and the Non-monotonic Ascension Dynamics
Meheboob Alam; Leonardo Trujillo; Hans J. Herrmann
2008-02-01
Based on the Boltzmann-Enskog kinetic theory, we develop a hydrodynamic theory for the well known (reverse) Brazil nut segregation in a vibro-fluidized granular mixture. Using an analogy with standard fluid mechanics, we have recently suggested a novel mechanism of segregation in granular mixtures based on a {\\it competition between buoyancy and geometric forces}: the Archimedean buoyancy force, a pseudo-thermal buoyancy force due to the difference between the energies of two granular species, and two geometric forces, one compressive and the other-one tensile in nature, due to the size-difference. For a mixture of perfectly hard-particles with elastic collisions, the pseudo-thermal buoyancy force is zero but the intruder has to overcome the net compressive geometric force to rise. For this case, the geometric force competes with the standard Archimedean buoyancy force to yield a threshold density-ratio, $R_{\\rho 1}=\\rho_l/\\rho_s R_{\\rho 1}$), above which the intruder rises again. Focussing on the {\\it tracer} limit of intruders in a dense binary mixture, we find that the rise-time of the intruder could vary {\\it non-monotonically} with the density-ratio. For a given size-ratio, there is a threshold density-ratio for the intruder at which it takes the maximum time to rise, and above(/below) which it rises faster, implying that {\\it the heavier (and larger) the intruder, the faster it ascends}. Our theory offers a unified description for the (reverse) Brazil-nut segregation and the non-monotonic ascension dynamics of Brazil-nuts.
Hydrodynamics of Fischer-Tropsch synthesis in slurry bubble column reactors: Final report
Bukur, D.B.; Daly, J.G.; Patel, S.A.; Raphael, M.L.; Tatterson, G.B.
1987-06-01
This report describes studies on hydrodynamics of bubble columns for Fischer-Tropsch synthesis. These studies were carried out in columns of 0.051 m and 0.229 m in diameter and 3 m tall to determine effects of operating conditions (temperature and gas flow rate), distributor type (sintered metal plate and single and multi-hole perforated plates) and liquid media (paraffin and reactor waxes) on gas hold-up and bubble size distribution. In experiments with the Fischer-Tropsch (F-T) derived paraffin wax (FT-300) for temperatures between 230 and 280/sup 0/C there is a range of gas velocities (transition region) where two values of gas hold-up (i.e., two flow regimes) are possible. Higher hold-ups were accompanied by the presence of foam (''foamy'' regime) whereas lower values were obtained in the absence of foam (''slug flow'' in the 0.051 m column, or ''churn-turbulent'' flow regime in the 0.229 m column). This type of behavior has been observed for the first time in a system with molten paraffin wax as the liquid medium. Several factors which have significant effect on foaming characteristics of this system were identified. Reactor waxes have much smaller tendency to foam and produce lower hold-ups due to the presence of larger bubbles. Finally, new correlations for prediction of the gas hold-up and the specific gas-liquid interfacial area were developed on the basis of results obtained in the present study. 49 refs., 99 figs., 19 tabs.
High-pressure three-phase fluidization: Hydrodynamics and heat transfer
Luo, X.; Jiang, P.; Fan, L.S.
1997-10-01
High-pressure operations are common in industrial applications of gas-liquid-solid fluidized-bed reactors for resid hydrotreating, Fischer-Tropsch synthesis, coal methanation, methanol synthesis, polymerization, and other reactions. The phase holdups and the heat-transfer behavior were studied experimentally in three-phase fluidized beds over a pressure range of 0.1--15.6 MPa. Bubble characteristics in the bed are examined by direct flow visualization. Pressure effects on the bubble coalescence and breakup are analyzed mechanistically. The study indicates that the pressure affects the hydrodynamics and heat-transfer properties of a three-phase fluidized bed significantly. The average bubble size decreases and the bubble-size distribution becomes narrower with an increase in pressure. The bubble-size reduction leads to an increase in the transition gas velocity from the dispersed bubble regime to the coalesced bubble regime, an increase in the gas holdup, and a decrease in the liquid and solids holdups. The pressure effect is insignificant above 6 MPa. The heat-transfer coefficient between an immersed surface and the bed increases to a maximum at pressure 6--8 MPa and then decreases with an increase in pressure at a given gas and liquid flow rate. This variation is attributed to the pressure effects on phase holdups and physical properties of the gas and liquid phases. A mechanistic analysis revealed that the major heat-transfer resistance in high-pressure three-phase fluidized beds resides in a liquid film surrounding the heat-0transfer surface. An empirical correlation is proposed to predict the heat-transfer coefficient under high-pressure conditions.
Radiation-Hydrodynamic Simulations of Massive Star Formation with Protostellar Outflows
Cunningham, A J; Klein, R I; Krumholz, M R; McKee, C F
2011-03-02
We report the results of a series of AMR radiation-hydrodynamic simulations of the collapse of massive star forming clouds using the ORION code. These simulations are the first to include the feedback effects protostellar outflows, as well as protostellar radiative heating and radiation pressure exerted on the infalling, dusty gas. We find that that outflows evacuate polar cavities of reduced optical depth through the ambient core. These enhance the radiative flux in the poleward direction so that it is 1.7 to 15 times larger than that in the midplane. As a result the radiative heating and outward radiation force exerted on the protostellar disk and infalling cloud gas in the equatorial direction are greatly diminished. The simultaneously reduces the Eddington radiation pressure barrier to high-mass star formation and increases the minimum threshold surface density for radiative heating to suppress fragmentation compared to models that do not include outflows. The strength of both these effects depends on the initial core surface density. Lower surface density cores have longer free-fall times and thus massive stars formed within them undergo more Kelvin contraction as the core collapses, leading to more powerful outflows. Furthermore, in lower surface density clouds the ratio of the time required for the outflow to break out of the core to the core free-fall time is smaller, so that these clouds are consequently influenced by outflows at earlier stages of collapse. As a result, outflow effects are strongest in low surface density cores and weakest in high surface density one. We also find that radiation focusing in the direction of outflow cavities is sufficient to prevent the formation of radiation pressure-supported circumstellar gas bubbles, in contrast to models which neglect protostellar outflow feedback.
A Smoothed Particle Hydrodynamics Model for Ice Sheet and Ice Shelf Dynamics
Pan, Wenxiao; Tartakovsky, Alexandre M.; Monaghan, Joseph J.
2012-02-08
Mathematical modeling of ice sheets is complicated by the non-linearity of the governing equations and boundary conditions. Standard grid-based methods require complex front tracking techniques and have limited capability to handle large material deformations and abrupt changes in bottom topography. As a consequence, numerical methods are usually restricted to shallow ice sheet and ice shelf approximations. We propose a new smoothed particle hydrodynamics (SPH) model for coupled ice sheet and ice shelf dynamics. SPH is a fully Lagrangian particle method. It is highly scalable and its Lagrangian nature and meshless discretization are well suited to the simulation of free surface flows, large material deformation, and material fragmentation. In this paper SPH is used to study ice sheet/ice shelf behavior, and the dynamics of the grounding line. The steady state position of the grounding line obtained from the SPH simulations is in good agreement with laboratory observations for a wide range of simulated bedrock slopes, and density ratios similar to those of ice and sea water. The numerical accuracy of the SPH algorithm is further verified by simulating the plane shear flow of two immiscible fluids and the propagation of a highly viscous blob of fluid along a horizontal surface. In the experiment, the ice was represented with a viscous newtonian fluid. For consistency, in the described SPH model the ice is also modeled as a viscous newtonian fluid. Typically, ice sheets are modeled as a non-Newtonian fluid, accounting for the changes in the mechanical properties of ice. Implementation of a non-Newtonian rheology in the SPH model is the subject of our ongoing research.
Smoothed particle hydrodynamics Non-Newtonian model for ice-sheet and ice-shelf dynamics
Pan, Wenxiao; Tartakovsky, Alexandre M.; Monaghan, Joseph J.
2013-06-01
Mathematical modeling of ice sheets is complicated by the non-linearity of the governing equations and boundary conditions. Standard grid-based methods require complex front tracking techniques and have limited capability to handle large material deformations and abrupt changes in bottom topography. As a consequence, numerical methods are usually restricted to shallow ice sheet and ice shelf approximations. We propose a new smoothed particle hydrodynamics (SPH) non-Newtonian model for coupled ice sheet and ice shelf dynamics. SPH, a fully Lagrangian particle method, is highly scalable and its Lagrangian nature and meshless discretization are well suited to the simulation of free surface ?ows, large material deformation, and material fragmentation. In this paper, SPH is used to study 3D ice sheet/ice shelf behavior, and the dynamics of the grounding line. The steady state position of the grounding line obtained from SPH simulations is in good agreement with laboratory observations for a wide range of simulated bedrock slopes, and density ratios, similar to those of ice and sea water. The numerical accuracy of the SPH algorithm is veri?ed by simulating Poiseuille ?ow, plane shear ?ow with free surface and the propagation of a blob of ice along a horizontal surface. In the laboratory experiment, the ice was represented with a viscous Newtonian ?uid. In the present work, however, the ice is modeled as both viscous Newtonian ?uid and non-Newtonian ?uid, such that the e?ect of non-Newtonian rheology on the dynamics of grounding line was examined. The non-Newtonian constitutive relation is prescribed to be Glen’s law for the creep of polycrystalline ice. A V-shaped bedrock ramp is further introduced to model the real geometry of bedrock slope.
Hitoshi Miura; Taishi Nakamoto
2006-11-09
Millimeter-sized, spherical silicate grains abundant in chondritic meteorites, which are called as chondrules, are considered to be a strong evidence of the melting event of the dust particles in the protoplanetary disk. One of the most plausible scenarios is that the chondrule precursor dust particles are heated and melt in the high-velocity gas flow (shock-wave heating model). We developed the non-linear, time-dependent, and three-dimensional hydrodynamic simulation code for analyzing the dynamics of molten droplets exposed to the gas flow. We confirmed that our simulation results showed a good agreement in a linear regime with the linear solution analytically derived by Sekiya et al. (2003). We found that the non-linear terms in the hydrodynamical equations neglected by Sekiya et al. (2003) can cause the cavitation by producing negative pressure in the droplets. We discussed that the fragmentation through the cavitation is a new mechanism to determine the upper limit of chondrule sizes. We also succeeded to reproduce the fragmentation of droplets when the gas ram pressure is stronger than the effect of the surface tension. Finally, we compared the deformation of droplets in the shock-wave heating with the measured data of chondrules and suggested the importance of other effects to deform droplets, for example, the rotation of droplets. We believe that our new code is a very powerful tool to investigate the hydrodynamics of molten droplets in the framework of the shock-wave heating model and has many potentials to be applied to various problems.
F. Herwig; T. Blöcker; D. Schönberner; M. El Eid
1997-06-12
The focus of this study is on the treatment of those stellar regions immediately adjacent to convective zones. The results of hydrodynamical simulations by Freytag et al. (1996, A&A313,497) show that the motion of convective elements extends well beyond the boundary of the convectively unstable region. We have applied their parametrized description of the corresponding velocities to the treatment of overshoot in stellar evolution calculations up to the AGB (Pop.I, M_zams=3M_sun).
Alberto A. Garcia Diaz
2014-12-17
Under the hydrodynamic equilibrium Buchdahl's conditions on the behavior of the density and the pressure, for regular fluid static circularly symmetric star in (2 + 1) dimensions in the presence of a cosmological constant, is established that there are no bounds from below on the pressure and also on the mass, except for their positiveness. The metric for a constant density distribution is derived and its matching with the external static solution with a negative cosmological constant is accomplished. Some mistakes of previous works on the topic are pointed out.
Yang, Zhaoqing; Wang, Taiping
2011-09-01
In this report we describe (1) the development, test, and validation of the marine hydrokinetic energy scheme in a three-dimensional coastal ocean model (FVCOM); and (2) the sensitivity analysis of effects of marine hydrokinetic energy configurations on power extraction and volume flux in a coastal bay. Submittal of this report completes the work on Task 2.1.2, Effects of Physical Systems, Subtask 2.1.2.1, Hydrodynamics and Subtask 2.1.2.3, Screening Analysis, for fiscal year 2011 of the Environmental Effects of Marine and Hydrokinetic Energy project.
Benitz, M. A.; Schmidt, D. P.; Lackner, M. A.; Stewart, G. M.; Jonkman, J.; Robertson, A.
2014-09-01
Hydrodynamic loads on the platforms of floating offshore wind turbines are often predicted with computer-aided engineering tools that employ Morison's equation and/or potential-flow theory. This work compares results from one such tool, FAST, NREL's wind turbine computer-aided engineering tool, and the computational fluid dynamics package, OpenFOAM, for the OC4-DeepCwind semi-submersible analyzed in the International Energy Agency Wind Task 30 project. Load predictions from HydroDyn, the offshore hydrodynamics module of FAST, are compared with high-fidelity results from OpenFOAM. HydroDyn uses a combination of Morison's equations and potential flow to predict the hydrodynamic forces on the structure. The implications of the assumptions in HydroDyn are evaluated based on this code-to-code comparison.
Miura, H; Miura, Hitoshi; Nakamoto, Taishi
2006-01-01
Millimeter-sized, spherical silicate grains abundant in chondritic meteorites, which are called as chondrules, are considered to be a strong evidence of the melting event of the dust particles in the protoplanetary disk. One of the most plausible scenarios is that the chondrule precursor dust particles are heated and melt in the high-velocity gas flow (shock-wave heating model). We developed the non-linear, time-dependent, and three-dimensional hydrodynamic simulation code for analyzing the dynamics of molten droplets exposed to the gas flow. We confirmed that our simulation results showed a good agreement in a linear regime with the linear solution analytically derived by Sekiya et al. (2003). We found that the non-linear terms in the hydrodynamical equations neglected by Sekiya et al. (2003) can cause the cavitation by producing negative pressure in the droplets. We discussed that the fragmentation through the cavitation is a new mechanism to determine the upper limit of chondrule sizes. We also succeeded t...
Stubbe, E.J.; VanHoenacker, L.; Otero, R.
1994-02-01
This report presents an assessment study for the use of the code RELAP 5/MOD3/5M5 in the calculation of transient hydrodynamic loads on safety and relief discharge pipes. Its predecessor, RELAP 5/MOD1, was found adequate for this kind of calculations by EPRI. The hydrodynamic loads are very important for the discharge piping design because of the fast opening of the valves and the presence of liquid in the upstream loop seals. The code results are compared to experimental load measurements performed at the Combustion Engineering Laboratory in Windsor (US). Those measurements were part of the PWR Valve Test Program undertaken by EPRI after the TMI-2 accident. This particular kind of transients challenges the applicability of the following code models: two-phase choked discharge; interphase drag in conditions with large density gradients; heat transfer to metallic structures in fast changing conditions; two-phase flow at abrupt expansions. The code applicability to this kind of transients is investigated. Some sensitivity analyses to different code and model options are performed. Finally, the suitability of the code and some modeling guidelines are discussed.
Rosenberg, M. J. [MIT (Massachusetts Inst. of Technology), Cambridge, MA (United States). Plasma Science and Fusion Center; Rinderknecht, H. G. [MIT (Massachusetts Inst. of Technology), Cambridge, MA (United States). Plasma Science and Fusion Center; Hoffman, N. M. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Amendt, P. A. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Atzeni, S. [Univ. of Roma, Roma (Italy). Dipartimento SBAI; Zylstra, A. B. [MIT (Massachusetts Inst. of Technology), Cambridge, MA (United States). Plasma Science and Fusion Center; Li, C. K. [MIT (Massachusetts Inst. of Technology), Cambridge, MA (United States). Plasma Science and Fusion Center; Seguin, F. H. [MIT (Massachusetts Inst. of Technology), Cambridge, MA (United States). Plasma Science and Fusion Center; Sio, H. [MIT (Massachusetts Inst. of Technology), Cambridge, MA (United States). Plasma Science and Fusion Center; Johnson, M. Gatu [MIT (Massachusetts Inst. of Technology), Cambridge, MA (United States). Plasma Science and Fusion Center; Frenje, J. A. [MIT (Massachusetts Inst. of Technology), Cambridge, MA (United States). Plasma Science and Fusion Center; Petrasso, R. D. [MIT (Massachusetts Inst. of Technology), Cambridge, MA (United States). Plasma Science and Fusion Center; Glebov, V. Yu. [Univ. of Rochester, NY (United States). Lab. for Laser Energetics; Stoeckl, C. [Univ. of Rochester, NY (United States). Lab. for Laser Energetics; Seka, W. [Univ. of Rochester, NY (United States). Lab. for Laser Energetics; Marshall, F. J. [Univ. of Rochester, NY (United States). Lab. for Laser Energetics; Delettrez, J. A. [Univ. of Rochester, NY (United States). Lab. for Laser EnergeticsUniv. of Rochester, NY (United States). Lab. for Laser Energetics; Sangster, T. C. [Univ. of Rochester, NY (United States). Lab. for Laser Energetics; Betti, R. [Univ. of Rochester, NY (United States). Lab. for Laser Energetics; Goncharov, V. N. [Univ. of Rochester, NY (United States). Lab. for Laser Energetics; Meyerhofer, D. D. [Univ. of Rochester, NY (United States). Lab. for Laser Energetics; Skupsky, S. [Univ. of Rochester, NY (United States). Lab. for Laser Energetics; Bellei, C. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Pino, J. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Wilks, S. C. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Kagan, G. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Molvig, K. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Nikroo, A. [General Atomics, San Diego, CA (United States)
2014-05-05
Clear evidence of the transition from hydrodynamiclike to strongly kinetic shock-driven implosions is, for the first time, revealed and quantitatively assessed. Implosions with a range of initial equimolar D^{3}He gas densities show that as the density is decreased, hydrodynamic simulations strongly diverge from and increasingly over-predict the observed nuclear yields, from a factor of ~2 at 3.1 mg/cm^{3} to a factor of 100 at 0.14 mg/cm^{3}. (The corresponding Knudsen number, the ratio of ion mean-free path to minimum shell radius, varied from 0.3 to 9; similarly, the ratio of fusion burn duration to ion diffusion time, another figure of merit of kinetic effects, varied from 0.3 to 14.) This result is shown to be unrelated to the effects of hydrodynamic mix. As a first step to garner insight into this transition, a reduced ion kinetic (RIK) model that includes gradient-diffusion and loss-term approximations to several transport processes was implemented within the framework of a one-dimensional radiation-transport code. After empirical calibration, the RIK simulations reproduce the observed yield trends, largely as a result of ion diffusion and the depletion of the reacting tail ions.
DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)
Rosenberg, M. J. [MIT (Massachusetts Inst. of Technology), Cambridge, MA (United States). Plasma Science and Fusion Center; Rinderknecht, H. G. [MIT (Massachusetts Inst. of Technology), Cambridge, MA (United States). Plasma Science and Fusion Center; Hoffman, N. M. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Amendt, P. A. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Atzeni, S. [Univ. of Roma, Roma (Italy). Dipartimento SBAI; Zylstra, A. B. [MIT (Massachusetts Inst. of Technology), Cambridge, MA (United States). Plasma Science and Fusion Center; Li, C. K. [MIT (Massachusetts Inst. of Technology), Cambridge, MA (United States). Plasma Science and Fusion Center; Seguin, F. H. [MIT (Massachusetts Inst. of Technology), Cambridge, MA (United States). Plasma Science and Fusion Center; Sio, H. [MIT (Massachusetts Inst. of Technology), Cambridge, MA (United States). Plasma Science and Fusion Center; Johnson, M. Gatu [MIT (Massachusetts Inst. of Technology), Cambridge, MA (United States). Plasma Science and Fusion Center; Frenje, J. A. [MIT (Massachusetts Inst. of Technology), Cambridge, MA (United States). Plasma Science and Fusion Center; Petrasso, R. D. [MIT (Massachusetts Inst. of Technology), Cambridge, MA (United States). Plasma Science and Fusion Center; Glebov, V. Yu. [Univ. of Rochester, NY (United States). Lab. for Laser Energetics; Stoeckl, C. [Univ. of Rochester, NY (United States). Lab. for Laser Energetics; Seka, W. [Univ. of Rochester, NY (United States). Lab. for Laser Energetics; Marshall, F. J. [Univ. of Rochester, NY (United States). Lab. for Laser Energetics; Delettrez, J. A. [Univ. of Rochester, NY (United States). Lab. for Laser EnergeticsUniv. of Rochester, NY (United States). Lab. for Laser Energetics; Sangster, T. C. [Univ. of Rochester, NY (United States). Lab. for Laser Energetics; Betti, R. [Univ. of Rochester, NY (United States). Lab. for Laser Energetics; Goncharov, V. N. [Univ. of Rochester, NY (United States). Lab. for Laser Energetics; Meyerhofer, D. D. [Univ. of Rochester, NY (United States). Lab. for Laser Energetics; Skupsky, S. [Univ. of Rochester, NY (United States). Lab. for Laser Energetics; Bellei, C. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Pino, J. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Wilks, S. C. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Kagan, G. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Molvig, K. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Nikroo, A. [General Atomics, San Diego, CA (United States)
2014-05-01
Clear evidence of the transition from hydrodynamiclike to strongly kinetic shock-driven implosions is, for the first time, revealed and quantitatively assessed. Implosions with a range of initial equimolar D3He gas densities show that as the density is decreased, hydrodynamic simulations strongly diverge from and increasingly over-predict the observed nuclear yields, from a factor of ~2 at 3.1 mg/cm3 to a factor of 100 at 0.14 mg/cm3. (The corresponding Knudsen number, the ratio of ion mean-free path to minimum shell radius, varied from 0.3 to 9; similarly, the ratio of fusion burn duration to ion diffusion time, another figure of merit of kinetic effects, varied from 0.3 to 14.) This result is shown to be unrelated to the effects of hydrodynamic mix. As a first step to garner insight into this transition, a reduced ion kinetic (RIK) model that includes gradient-diffusion and loss-term approximations to several transport processes was implemented within the framework of a one-dimensional radiation-transport code. After empirical calibration, the RIK simulations reproduce the observed yield trends, largely as a result of ion diffusion and the depletion of the reacting tail ions.
Molnar, Sandor M. [Leung Center for Cosmology and Particle Astrophysics, National Taiwan University, Taipei 10617, Taiwan (China); Chiu, I-Non Tim [Department of Physics, Ludwig-Maximilians University, Scheinerstr 1, D-81679 Munich (Germany); Broadhurst, Tom [Department of Theoretical Physics, University of the Basque Country, E-48080 Bilbao (Spain); Stadel, Joachim G., E-mail: sandor@phys.ntu.edu.tw [Institute for Theoretical Physics, University of Zurich, 8057 Zurich (Switzerland)
2013-12-10
Since the discovery of the 'Bullet Cluster', several similar cases have been uncovered that suggest relative velocities well beyond the tail of high speed collisions predicted by the concordance ?CDM model. However, quantifying such post-merger events with hydrodynamical models requires a wide coverage of possible initial conditions. Here, we show that it is simpler to interpret pre-merger cases, such as A1750, where the gas between the colliding clusters is modestly affected, so that the initial conditions are clear. We analyze publicly available Chandra data confirming a significant increase in the projected X-ray temperature between the two cluster centers in A1750 consistent with our expectations for a merging cluster. We model this system with a self-consistent hydrodynamical simulation of dark matter and gas using the FLASH code. Our simulations reproduce well the X-ray data and the measured redshift difference between the two clusters in the phase before the first core passage viewed at an intermediate projection angle. The deprojected initial relative velocity derived using our model is 1460 km s{sup –1}, which is considerably higher than the predicted mean impact velocity for simulated massive haloes derived by recent ?CDM cosmological simulations, but is within the allowed range. Our simulations demonstrate that such systems can be identified using a multi-wavelength approach and numerical simulations, for which the statistical distribution of relative impact velocities may provide a definitive examination of a broad range of dark matter scenarios.
DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)
Rosenberg, M. J.; Rinderknecht, H. G.; Hoffman, N. M.; Amendt, P. A.; Atzeni, S.; Zylstra, A. B.; Li, C. K.; Seguin, F. H.; Sio, H.; Johnson, M. Gatu; et al
2014-05-05
Clear evidence of the transition from hydrodynamiclike to strongly kinetic shock-driven implosions is, for the first time, revealed and quantitatively assessed. Implosions with a range of initial equimolar D3He gas densities show that as the density is decreased, hydrodynamic simulations strongly diverge from and increasingly over-predict the observed nuclear yields, from a factor of ~2 at 3.1 mg/cm3 to a factor of 100 at 0.14 mg/cm3. (The corresponding Knudsen number, the ratio of ion mean-free path to minimum shell radius, varied from 0.3 to 9; similarly, the ratio of fusion burn duration to ion diffusion time, another figure of meritmore »of kinetic effects, varied from 0.3 to 14.) This result is shown to be unrelated to the effects of hydrodynamic mix. As a first step to garner insight into this transition, a reduced ion kinetic (RIK) model that includes gradient-diffusion and loss-term approximations to several transport processes was implemented within the framework of a one-dimensional radiation-transport code. After empirical calibration, the RIK simulations reproduce the observed yield trends, largely as a result of ion diffusion and the depletion of the reacting tail ions.« less
Cassibry, J. T.; Stanic, M.; Hsu, S. C.
2013-03-15
This work presents scaling relations for the peak thermal pressure and stagnation time (over which peak pressure is sustained) for an imploding spherical plasma liner formed by an array of merging plasma jets. Results were derived from three-dimensional (3D) ideal hydrodynamic simulation results obtained using the smoothed particle hydrodynamics code SPHC. The 3D results were compared to equivalent one-dimensional (1D) simulation results. It is found that peak thermal pressure scales linearly with the number of jets and initial jet density and Mach number, quadratically with initial jet radius and velocity, and inversely with the initial jet length and the square of the chamber wall radius. The stagnation time scales approximately as the initial jet length divided by the initial jet velocity. Differences between the 3D and 1D results are attributed to the inclusion of thermal transport, ionization, and perfect symmetry in the 1D simulations. A subset of the results reported here formed the initial design basis for the Plasma Liner Experiment [S. C. Hsu et al., Phys. Plasmas 19, 123514 (2012)].
Margraf, J
2012-06-12
This report primarily concerns the use of two massively parallel finite element codes originally written and maintained at Lawrence Livermore National Laboratory. ALE3D is an explicit hydrodynamics code commonly employed to simulate wave propagation from high energy scenarios and the resulting interaction with nearby structures. This coupled response ensures that a structure is accurately applied with a blast loading varying both in space and time. Figure 1 illustrates the radial outward propagation of a pressure wave due to a center detonated spherical explosive originating from the lower left. The radial symmetry seen in this scenario is lost when instead a cylindrocal charge is detonated. Figure 2 indicates that a stronger, faster traveling pressure wave occurs in the direction of the normal axis to the cylinder. The ALE3D name is derived because of the use of arbitrary-Lagrange-Eulerian elements in which the mesh is allowed to advect; a process through which the mesh is modified to alleviate tanlging and general mesh distortion often cuased by high energy scenarios. The counterpart to an advecting element is a Lagrange element, whose mesh moves with the material. Ideally all structural components are kept Lagrange as long as possible to preserve accuracy of material variables and minimize advection related errors. Advection leads to mixed zoning, so using structural Lagrange elements also improves the visualization when post processing the results. A simplified representation of the advection process is shown in Figure 3. First the mesh is distorted due to material motion during the Lagrange step. The mesh is then shifted to an idealized and less distorted state to prevent irregular zones caused by the Lagrange motion. Lastly, the state variables are remapped to the elements of the newly constructed mesh. Note that Figure 3 represents a purely Eulerian mesh relaxation because the mesh is relocated back to the pre-Lagrange position. This is the case when the material flows through a still mesh. This is not typically done in an ALE3D analysis, especially if Lagrange elements exist. Deforming Lagrange elements would certainly tangle with a Eulerian mesh eventually. The best method in this case is to have an advecting mesh positioned as some relaxed version of the pre and post Lagrange step; this gives the best opportunity of modeling a high energy event with a combination of Lagrange and ALE elements. Dyne3D is another explicit dynamic analysis code, ParaDyn being the parallel version. ParaDyn is used for predicting the transient response of three dimensional structures using Lagrangian solid mechanics. Large deformation and mesh tangling is often resolved through the use of an element deletion scheme. This is useful to accommodate component failure, but if it is done purely as a means to preserve a useful mesh it can lead to problems because it does not maintain continuity of the material bulk response. Whatever medium exists between structural components is typically not modeled in ParaDyn. Instead, a structure either has a known loading profile applied or given initial conditions. The many included contact algorithms can calculate the loading response of materials if and when they collide. A recent implementation of an SPH module in which failed or deleted material nodes are converted to independent particles is currently being utilized for a variety of spall related problems and high velocity impact scenarios. Figure 4 shows an example of a projectile, given an initial velocity, and how it fails the first plate which generates SPH particles which then interact with and damage the second plate.
Kroupp, Eyal
Ion Temperature and Hydrodynamic-Energy Measurements in a Z-Pinch Plasma at Stagnation E. Kroupp, D. Fisher Faculty of Physics, Technion-Israeli Institute of Technology, Haifa, Israel M. E. Cuneo Sandia and the random hydrodynamic motion to the line shapes. In Z-pinch ex- periments [1,3], the plasma kinetic energy
Lauder, George V.
2002-01-01
. But the orientations and magnitudes of these forces, the mechanisms by which they are generated, and how fish modulate reveal that lateral forces are high relative to thrust force, and that mechanical performance of median propulsor may also enhance stability and maneuverability. Analysis of hydrodynamic function of the soft
Rasio, Frederic A.
is relatively suppressed compared to the synchronized case, but shows a very significant second peak of emission with theoretical knowledge about the hydrody- namics of the merger process, could yield detailed informa- tion knowledge using 3D numerical hydrodynamics calculations of NS mergers in post- Newtonian PN gravity
O R I G I N A L A R T I C L E The hydrodynamics of hovering in Antarctic
-to-intermediate Reynolds number regime, hover by beating their pleopods (or swimming legs) in a metachronal wave from back) to drag flow backward during its power stroke and contracts and folds the distal leg segments to minimize] The hydrodynamics of drag-based propulsion via a t
Deymier, Pierre
Modeling the coupling of reaction kinetics and hydrodynamics in a collapsing cavity Sudib K. Mishra Available online 22 May 2009 Keywords: Cavitation Reaction Multiphase Lattice Boltzmann Model Stochastic a b s t r a c t We introduce a model of cavitation based on the multiphase Lattice Boltzmann method (LBM
Grant, Martin
2008-01-01
-Hiroshima 739-8526, Japan Received 3 March 2008 / Received in final form 26 August 2008 Published online 4-scale dislocation motion, can be generated using a simple, numerically cost-effective, nonlinear scalar equa- tion hydrodynamic mode which has quasi-wave characteristics. These waves are not true phonons because they only live
Lauder, George V.
2015-01-01
Bioinspir. Biomim. 10 (2015) 066010 doi:10.1088/1748-3190/10/6/066010 PAPER Hydrodynamic function fabricated with rigid denticles (scales) on a flexible substrate. This artificial skin can bend and generate denticle patterns on locomotion. In this paper we investigate the effect of changing the spacing
Pan, Ning
5(1) 5-8, 2004 Thermo-electro-hydrodynamic model for electrospinning process Yu-Qin Wana , Qian Guob-fine polymer fibers, obtained by electrospinning, have a wide range of potential applications such as fluid behind electrospinning. When electrical force is dominant over the other forces, Bratu equation
US Army Corps of Engineers
Inlet, FL. Proceedings Coastal Sediments '07 Conference, ASCE Press, Reston, VA, 1297-1310. HYDRODYNAMIC Modeling System (CMS) to investigate the morphological response to time varying forcing, sediment texture evolution of tidal inlet shoals is an important management tool, since they control sediment budgets. Inlet
Tsibidis, George D; Stratakis, Emmanuel
2015-01-01
Materials irradiated with multiple femtosecond laser pulses in sub-ablation conditions are observed to develop various types of self-assembled morphologies that range from nano-ripples to periodic micro-grooves and quasi-periodic micro-spikes. Here, we present a physical scenario that couples electrodynamics, describing surface plasmon excitation, with hydrodynamics, describing Marangoni convection, to elucidate this important sub-ablation regime of light matter interaction in which matter is being modified, however, the underlying process is not yet fully understood. The proposed physical mechanism could be generally applicable to practically any conductive material structured by ultrashort laser pulses, therefore it can be useful for the interpretation of further critical aspects of light matter interaction.
Wang, Liang; Stinson, Gregory S; Macciò, Andrea V; Penzo, Camilla; Kang, Xi; Keller, Ben W; Wadsley, James
2015-01-01
We introduce project NIHAO (Numerical Investigation of a Hundred Astrophysical Objects), a set of 100 cosmological zoom-in hydrodynamical simulations performed using the GASOLINE code, with an improved implementation of the SPH algorithm. The haloes in our study range from dwarf to Milky Way masses, and represent an unbiased sampling of merger histories, concentrations and spin parameters. The particle masses and force softenings are chosen to resolve the mass profile to below 1% of the virial radius at all masses, ensuring that galaxy half-light radii are well resolved. Using the same treatment of star formation and stellar feedback for every object, the simulated galaxies reproduce the observed inefficiency of galaxy formation across cosmic time as expressed through the stellar mass vs halo mass relation, and the star formation rate vs stellar mass relation. We thus conclude that stellar feedback is the chief piece of physics required to limit the efficiency of star formation in galaxies less massive than t...
Ilya Martchenko; Nikolai Tsvetkov
2008-09-23
Samples of third-generation cylindrical dendrimers with molar masses ranging in the interval 20000...60000 have been studied by the methods of equilibrium and non-equilibrium electrical birefringence, molecular hydrodynamics and optics. It was found that the absolute values of Kerr and flow birefringence constants exceed the values obtained for analogous dendrimers of lower generations. The mechanism of reorientation has proven to be strongly dependent on the physical and chemical properties of the solvent. In chloroform solutions, the studied dendrimers align to the microwave-frequency electric fields according to large-scale mechanism. In dichloroacetic acid solutions, the observed reorientation mechanism is low-scale, which is explained by degradation of intermolecular hydrogen bonds. Terminal dendritic substituents of the macromolecules have experimentally proven to be oriented mainly along the primary polymer chain.
Jiang, Z J; Ma, K; Zhang, H L
2015-01-01
The charged particles produced in nucleus-nucleus collisions are divided into two parts. One is from the hot and dense matter created in collisions. The other is from leading particles. The hot and dense matter is assumed to expand according to unified hydrodynamics and freezes out into charged particles from a space-like hypersurface with a fixed proper time of Tau_FO.The leading particles are conventionally taken as the particles which inherit the quantum numbers of colliding nucleons and carry off most of incident energy. The rapidity distributions of the charged particles from these two parts are formulated analytically, and a comparison is made between the theoretical results and the experimental measurements performed in Au-Au and Pb-Pb collisions at the respective BNL-RHIC and CERN-LHC energies. The theoretical results are well consistent with experimental data.
Mikhailenko, V. V.; Mikhailenko, V. S.; Lee, Hae June; Koepke, M. E.
2014-07-15
The cross-magnetic-field (i.e., perpendicular) profile of ion temperature and the perpendicular profile of the magnetic-field-aligned (parallel) plasma flow are sometimes inhomogeneous for space and laboratory plasma. Instability caused either by a gradient in the ion-temperature profile or by shear in the parallel flow has been discussed extensively in the literature. In this paper, (1) hydrodynamic plasma stability is investigated, (2) real and imaginary frequency are quantified over a range of the shear parameter, the normalized wavenumber, and the ratio of density-gradient and ion-temperature-gradient scale lengths, and (3) the role of inverse Landau damping is illustrated for the case of combined ion-temperature gradient and parallel-flow shear. We find that increasing the ion-temperature gradient reduces the instability threshold for the hydrodynamic parallel-flow shear instability, also known as the parallel Kelvin-Helmholtz instability or the D'Angelo instability. We also find that a kinetic instability arises from the coupled, reinforcing action of both free-energy sources. For the case of comparable electron and ion temperature, we illustrate analytically the transition of the D'Angelo instability to the kinetic instability as (a) the shear parameter, (b) the normalized wavenumber, and (c) the ratio of density-gradient and ion-temperature-gradient scale lengths are varied and we attribute the changes in stability to changes in the amount of inverse ion Landau damping. We show that near a normalized wavenumber k{sub ?}?{sub i} of order unity (i) the real and imaginary values of frequency become comparable and (ii) the imaginary frequency, i.e., the growth rate, peaks.
Elisabetta Caffau; L. Sbordone; H. -G. Ludwig; P. Bonifacio; M. Steffen; N. T. Behara
2008-03-25
Context: The stable element hafnium (Hf) and the radioactive element thorium (Th) were recently suggested as a suitable pair for radioactive dating of stars. The applicability of this elemental pair needs to be established for stellar spectroscopy. Aims: We aim at a spectroscopic determination of the abundance of Hf and Th in the solar photosphere based on a \\cobold 3D hydrodynamical model atmosphere. We put this into a wider context by investigating 3D abundance corrections for a set of G- and F-type dwarfs. Method: High-resolution, high signal-to-noise solar spectra were compared to line synthesis calculations performed on a solar CO5BOLD model. For the other atmospheres, we compared synthetic spectra of CO5BOLD 3D and associated 1D models. Results: For Hf we find a photospheric abundance A(Hf)=0.87+-0.04, in good agreement with a previous analysis, based on 1D model atmospheres. The weak Th ii 401.9 nm line constitutes the only Th abundance indicator available in the solar spectrum. It lies in the red wing of an Ni-Fe blend exhibiting a non-negligible convective asymmetry. Accounting for the asymmetry-related additional absorption, we obtain A(Th)=0.09+-0.03, consistent with the meteoritic abundance, and about 0.1 dex lower than obtained in previous photospheric abundance determinations. Conclusions: Only for the second time, to our knowledge, has am non-negligible effect of convective line asymmetries on an abundance derivation been highlighted. Three-dimensional hydrodynamical simulations should be employed to measure Th abundances in dwarfs if similar blending is present, as in the solar case. In contrast, 3D effects on Hf abundances are small in G- to mid F-type dwarfs and sub-giants, and 1D model atmospheres can be conveniently used.
Eyal Heifetz; Eliahu Cohen
2015-06-18
We revisit the analogy suggested by Madelung between a non-relativistic time-dependent quantum particle, to a fluid system which is pseudo-barotropic, irrotational and inviscid. We first discuss the hydrodynamical properties of the Madelung description in general, and extract a pressure like term from the Bohm potential. We show that the existence of a pressure gradient force in the fluid description does not violate Ehrenfest's theorem since its expectation value is zero. We also point out that incompressibility of the fluid implies conservation of density along a fluid parcel trajectory and in 1D this immediately results in the non-spreading property of wave packets, as the sum of Bohm potential and an exterior potential must be either constant or linear in space. Next we relate to the hydrodynamic description a thermodynamic counterpart, taking the classical behavior of an adiabatic barotopric flow as a reference. We show that while the Bohm potential is not a positive definite quantity, as is expected from internal energy, its expectation value is proportional to the Fisher information whose integrand is positive definite. Moreover, this integrand is exactly equal to half of the square of the imaginary part of the momentum, as the integrand of the kinetic energy is equal to half of the square of the real part of the momentum. This suggests a relation between the Fisher information and the thermodynamic like internal energy of the Madelung fluid. Furthermore, it provides a physical linkage between the inverse of the Fisher information and the measure of disorder in quantum systems - in spontaneous adiabatic gas expansion the amount of disorder increases while the internal energy decreases.
Analysis of Maneuvering Fish Fin Hydrodynamics Using an Immersed Boundary Method
Mittal, Rajat
Ramakrishnan and Rajat Mittal Department of Mechanical and Aerospace Engineering George Washington University Meliha Bozkurttas§ Department of Mechanical and Aerospace Engineering George Washington University macrochirus) provides insight that can be applied to the design of propulsors for autonomous underwater
Castaneda, Jaime N.; Cote, Raymond O.; Torczynski, John Robert; O'Hern, Timothy John
2004-05-01
An experimental program was conducted to study a proposed approach for oil reintroduction in the Strategic Petroleum Reserve (SPR). The goal was to assess whether useful oil is rendered unusable through formation of a stable oil-brine emulsion during reintroduction of degassed oil into the brine layer in storage caverns. An earlier report (O'Hern et al., 2003) documented the first stage of the program, in which simulant liquids were used to characterize the buoyant plume that is produced when a jet of crude oil is injected downward into brine. This report documents the final two test series. In the first, the plume hydrodynamics experiments were completed using SPR oil, brine, and sludge. In the second, oil reinjection into brine was run for approximately 6 hours, and sampling of oil, sludge, and brine was performed over the next 3 months so that the long-term effects of oil-sludge mixing could be assessed. For both series, the experiment consisted of a large transparent vessel that is a scale model of the proposed oil-injection process at the SPR. For the plume hydrodynamics experiments, an oil layer was floated on top of a brine layer in the first test series and on top of a sludge layer residing above the brine in the second test series. The oil was injected downward through a tube into the brine at a prescribed depth below the oil-brine or sludge-brine interface. Flow rates were determined by scaling to match the ratio of buoyancy to momentum between the experiment and the SPR. Initially, the momentum of the flow produces a downward jet of oil below the tube end. Subsequently, the oil breaks up into droplets due to shear forces, buoyancy dominates the flow, and a plume of oil droplets rises to the interface. The interface was deflected upward by the impinging oil-brine plume. Videos of this flow were recorded for scaled flow rates that bracket the equivalent pumping rates in an SPR cavern during injection of degassed oil. Image-processing analyses were performed to quantify the penetration depth and width of the oil jet. The measured penetration depths were shallow, as predicted by penetration-depth models, in agreement with the assumption that the flow is buoyancy-dominated, rather than momentum-dominated. The turbulent penetration depth model overpredicted the measured values. Both the oil-brine and oil-sludge-brine systems produced plumes with hydrodynamic characteristics similar to the simulant liquids previously examined, except that the penetration depth was 5-10% longer for the crude oil. An unexpected observation was that centimeter-size oil 'bubbles' (thin oil shells completely filled with brine) were produced in large quantities during oil injection. The mixing experiments also used layers of oil, sludge, and brine from the SPR. Oil was injected at a scaled flow rate corresponding to the nominal SPR oil injection rates. Injection was performed for about 6 hours and was stopped when it was evident that brine was being ingested by the oil withdrawal pump. Sampling probes located throughout the oil, sludge, and brine layers were used to withdraw samples before, during, and after the run. The data show that strong mixing caused the water content in the oil layer to increase sharply during oil injection but that the water content in the oil dropped back to less than 0.5% within 16 hours after injection was terminated. On the other hand, the sediment content in the oil indicated that the sludge and oil appeared to be well mixed. The sediment settled slowly but the oil had not returned to the baseline, as-received, sediment values after approximately 2200 hours (3 months). Ash content analysis indicated that the sediment measured during oil analysis was primarily organic.
VALIDATION OF A HYDRODYNAMIC MODEL OF DELAWARE BAY AND THE ADJACENT
Kirby, James T.
Engineering Laboratory University of Delaware Newark, Delaware 19716 #12;iii TABLE OF CONTENTS LIST OF TABLES.3 Curvilinear Coordinates............................................................................. 9 2.4 Vertical Coordinates.................................................................................. 9 2
Gao, Li-Na
2015-01-01
We propose a new revised Landau hydrodynamic model to study systematically the pseudorapidity distributions of charged particles produced in heavy ion collisions over an energy range from a few GeV to a few TeV per nucleon pair. The interacting system is divided into three sources namely the central, target, and projectile sources respectively. The large central source is described by the Landau hydrodynamic model and further revised by the contributions of the small target/projectile sources. In the calculation, to avoid the errors caused by an unapt conversion or non-division, the rapidity and pseudorapidity distributions are obtained respectively. The modeling results are in agreement with the available experimental data at relativistic heavy ion collider (RHIC), large hadron collider (LHC), and other energies for different centralities. The value of square speed of sound parameter in different collisions has been extracted by us from the widths of rapidity distributions. Our results show that, in heavy io...
Romeo, A D; Contini, E; Sommer-Larsen, J; Fassbender, R; Napolitano, N R; Antonuccio-Delogu, V; Gavignaud, I
2015-01-01
By means of our own cosmological-hydrodynamical simulation and semi-analytical model we studied galaxy population properties in clusters and groups, spanning over 10 different bands from UV to NIR, and their evolution since redshift z=2. We compare our results in terms of galaxy red/blue fractions and luminous-to-faint ratio (LFR) on the Red Sequence (RS) with recent observational data reaching beyond z=1.5. Different selection criteria were tested in order to retrieve galaxies belonging to the RS: either by their quiescence degree measured from their specific SFR ("Dead Sequence"), or by their position in a colour-colour plane which is also a function of sSFR. In both cases, the colour cut and the limiting magnitude threshold were let evolving with redshift, in order to follow the natural shift of the characteristic luminosity in the LF. We find that the Butcher-Oemler effect is wavelength-dependent, with the fraction of blue galaxies increasing steeper in optical colours than in NIR. Besides, only when appl...
Donna Post Guillen; Daniel S. Wendt; Steven P. Antal; Michael Z. Podowski
2007-11-01
The purpose of this paper is to document the review of several open-literature sources of both experimental capabilities and published hydrodynamic data to aid in the validation of a Computational Fluid Dynamics (CFD) based model of a slurry bubble column (SBC). The review included searching the Web of Science, ISI Proceedings, and Inspec databases, internet searches as well as other open literature sources. The goal of this study was to identify available experimental facilities and relevant data. Integral (i.e., pertaining to the SBC system), as well as fundamental (i.e., separate effects are considered), data are included in the scope of this effort. The fundamental data is needed to validate the individual mechanistic models or closure laws used in a Computational Multiphase Fluid Dynamics (CMFD) simulation of a SBC. The fundamental data is generally focused on simple geometries (i.e., flow between parallel plates or cylindrical pipes) or custom-designed tests to focus on selected interfacial phenomena. Integral data covers the operation of a SBC as a system with coupled effects. This work highlights selected experimental capabilities and data for the purpose of SBC model validation, and is not meant to be an exhaustive summary.
Donna Post Guillen; Daniel S. Wendt
2007-11-01
The purpose of this paper is to document the review of several open-literature sources of both experimental capabilities and published hydrodynamic data to aid in the validation of a Computational Fluid Dynamics (CFD) based model of a slurry bubble column (SBC). The review included searching the Web of Science, ISI Proceedings, and Inspec databases, internet searches as well as other open literature sources. The goal of this study was to identify available experimental facilities and relevant data. Integral (i.e., pertaining to the SBC system), as well as fundamental (i.e., separate effects are considered), data are included in the scope of this effort. The fundamental data is needed to validate the individual mechanistic models or closure laws used in a Computational Multiphase Fluid Dynamics (CMFD) simulation of a SBC. The fundamental data is generally focused on simple geometries (i.e., flow between parallel plates or cylindrical pipes) or custom-designed tests to focus on selected interfacial phenomena. Integral data covers the operation of a SBC as a system with coupled effects. This work highlights selected experimental capabilities and data for the purpose of SBC model validation, and is not meant to be an exhaustive summary.
Melin, Alexander M; Kisner, Roger A; Fugate, David L; Holcomb, David Eugene
2015-01-01
Embedding instrumentation and control Embedding instrumentation and control (I\\&C) at the component level in nuclear power plants can improve component performance, lifetime, and resilience by optimizing operation, reducing the constraints on physical design, and providing on-board prognostics and diagnostics. However, the extreme environments that many nuclear power plant components operate in makes embedding instrumentation and control at the component level difficult. Successfully utilizing embedded I\\&C requires developing a deep understanding of the system's dynamics and using that knowledge to overcome material and physical limitations imposed by the environment. In this paper, we will develop a coupled dynamic model of a high temperature (700 $^\\circ$C) canned rotor pump that incorporates rotordynamics, hydrodynamics, and active magnetic bearing dynamics. Then we will compare two control design methods, one that uses a simplified decoupled model of the system and another that utilizes the full coupled system model. It will be seen that utilizing all the available knowledge of the system dynamics in the controller design yield an order of magnitude improvement in the magnitude of the magnetic bearing response to disturbances at the same level of control effort, a large reduction in the settling time of the system, and a smoother control action.
Tanikawa, Ataru; Sato, Yushi; Nomoto, Ken'ichi; Maeda, Keiichi; Hachisu, Izumi
2015-01-01
We perform smoothed particle hydrodynamics (SPH) simulations for merging binary carbon-oxygen (CO) white dwarfs (WDs) with masses of $1.1$ and $1.0$ $M_\\odot$, until the merger remnant reaches a dynamically steady state. Using these results, we assess whether the binary could induce a thermonuclear explosion, and whether the explosion could be observed as a type Ia supernova (SN Ia). We investigate three explosion mechanisms: a helium-ignition following the dynamical merger (`helium-ignited violent merger model'), a carbon-ignition (`carbon-ignited violent merger model'), and an explosion following the formation of the Chandrasekhar mass WD (`Chandrasekhar mass model'). An explosion of the helium-ignited violent merger model is possible, while we predict that the resulting SN ejecta are highly asymmetric since its companion star is fully intact at the time of the explosion. The carbon-ignited violent merger model can also lead to an explosion. However, the envelope of the exploding WD spreads out to $\\sim 0.1...
An axisymmetric hydrodynamical model for the torus wind in AGN. II: X-ray excited funnel flow
Dorodnitsyn, A; Proga, D
2008-01-01
We have calculated a series of models of outflows from the obscuring torus in active galactic nuclei (AGN). Our modeling assumes that the inner face of a rotationally supported torus is illuminated and heated by the intense X-rays from the inner accretion disk and black hole. As a result of such heating a strong biconical outflow is observed in our simulations. We calculate 3-dimensional hydrodynamical models, assuming axial symmetry, and including the effects of X-ray heating, ionization, and radiation pressure. We discuss the behavior of a large family of these models, their velocity fields, mass fluxes and temperature, as functions of the torus properties and X-ray flux. Synthetic warm absorber spectra are calculated, assuming pure absorption, for sample models at various inclination angles and observing times. We show that these models have mass fluxes and flow speeds which are comparable to those which have been inferred from observations of Seyfert 1 warm absorbers, and that they can produce rich absorp...
An axisymmetric hydrodynamical model for the torus wind in AGN. II: X-ray excited funnel flow
A. Dorodnitsyn; T. Kallman; D. Proga
2008-06-23
We have calculated a series of models of outflows from the obscuring torus in active galactic nuclei (AGN). Our modeling assumes that the inner face of a rotationally supported torus is illuminated and heated by the intense X-rays from the inner accretion disk and black hole. As a result of such heating a strong biconical outflow is observed in our simulations. We calculate 3-dimensional hydrodynamical models, assuming axial symmetry, and including the effects of X-ray heating, ionization, and radiation pressure. We discuss the behavior of a large family of these models, their velocity fields, mass fluxes and temperature, as functions of the torus properties and X-ray flux. Synthetic warm absorber spectra are calculated, assuming pure absorption, for sample models at various inclination angles and observing times. We show that these models have mass fluxes and flow speeds which are comparable to those which have been inferred from observations of Seyfert 1 warm absorbers, and that they can produce rich absorption line spectra.
Takiwaki, Tomoya; Kotake, Kei [Center for Computational Astrophysics, National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588 (Japan); Suwa, Yudai [Yukawa Institute for Theoretical Physics, Kyoto University, Oiwake-cho, Kitashirakawa, Sakyo-ku, Kyoto 606-8502 (Japan)
2014-05-10
We present numerical results on two- (2D) and three-dimensional (3D) hydrodynamic core-collapse simulations of an 11.2 M {sub ?} star. By changing numerical resolutions and seed perturbations systematically, we study how the postbounce dynamics are different in 2D and 3D. The calculations were performed with an energy-dependent treatment of the neutrino transport based on the isotropic diffusion source approximation scheme, which we have updated to achieve a very high computational efficiency. All of the computed models in this work, including nine 3D models and fifteen 2D models, exhibit the revival of the stalled bounce shock, leading to the possibility of explosion. All of them are driven by the neutrino-heating mechanism, which is fostered by neutrino-driven convection and the standing-accretion-shock instability. Reflecting the stochastic nature of multi-dimensional (multi-D) neutrino-driven explosions, the blast morphology changes from model to model. However, we find that the final fate of the multi-D models, whether an explosion is obtained or not, is little affected by the explosion stochasticity. In agreement with some previous studies, higher numerical resolutions lead to slower onset of the shock revival in both 2D and 3D. Based on the self-consistent supernova models leading to the possibility of explosions, our results systematically show that the revived shock expands more energetically in 2D than in 3D.
Dall'Ora, M.; Botticella, M. T.; Della Valle, M. [INAF, Osservatorio Astronomico di Capodimonte, Napoli (Italy); Pumo, M. L.; Zampieri, L.; Tomasella, L.; Cappellaro, E.; Benetti, S. [INAF, Osservatorio Astronomico di Padova, I-35122 Padova (Italy); Pignata, G.; Bufano, F. [Departamento de Ciencias Fisicas, Universidad Andres Bello, Avda. Republica 252, Santiago (Chile); Bayless, A. J. [Southwest Research Institute, Department of Space Science, 6220 Culebra Road, San Antonio, TX 78238 (United States); Pritchard, T. A. [Department of Astronomy and Astrophysics, Penn State University, 525 Davey Lab, University Park, PA 16802 (United States); Taubenberger, S.; Benitez, S. [Max-Planck-Institut für Astrophysik, Karl-Schwarzschild-Str. 1, D-85741 Garching (Germany); Kotak, R.; Inserra, C.; Fraser, M. [Astrophysics Research Centre, School of Mathematics and Physics, Queen's University Belfast, Belfast, BT7 1NN (United Kingdom); Elias-Rosa, N. [Institut de Ciències de l'Espai (CSIC-IEEC) Campus UAB, Torre C5, Za plata, E-08193 Bellaterra, Barcelona (Spain); Haislip, J. B. [Department of Physics and Astronomy, University of North Carolina at Chapel Hill, 120 E. Cameron Ave., Chapel Hill, NC 27599 (United States); Harutyunyan, A. [Fundación Galileo Galilei - Telescopio Nazionale Galileo, Rambla José Ana Fernández Pérez 7, E-38712 Breña Baja, TF - Spain (Spain); and others
2014-06-01
We present an extensive optical and near-infrared photometric and spectroscopic campaign of the Type IIP supernova SN 2012aw. The data set densely covers the evolution of SN 2012aw shortly after the explosion through the end of the photospheric phase, with two additional photometric observations collected during the nebular phase, to fit the radioactive tail and estimate the {sup 56}Ni mass. Also included in our analysis is the previously published Swift UV data, therefore providing a complete view of the ultraviolet-optical-infrared evolution of the photospheric phase. On the basis of our data set, we estimate all the relevant physical parameters of SN 2012aw with our radiation-hydrodynamics code: envelope mass M {sub env} ? 20 M {sub ?}, progenitor radius R ? 3 × 10{sup 13} cm (?430 R {sub ?}), explosion energy E ? 1.5 foe, and initial {sup 56}Ni mass ?0.06 M {sub ?}. These mass and radius values are reasonably well supported by independent evolutionary models of the progenitor, and may suggest a progenitor mass higher than the observational limit of 16.5 ± 1.5 M {sub ?} of the Type IIP events.
Baumgaertel, J. A.; Bradley, P. A.; Hsu, S. C.; Cobble, J. A.; Hakel, P.; Tregillis, I. L.; Krasheninnikova, N. S.; Murphy, T. J.; Schmitt, M. J.; Shah, R. C.; Obrey, K. D.; Batha, S.; Johns, H.; Joshi, T.; Mayes, D.; Mancini, R. C.; Nagayama, T.
2014-05-15
Temporally, spatially, and spectrally resolved x-ray image data from direct-drive implosions on OMEGA were interpreted with the aid of radiation-hydrodynamic simulations. Neither clean calculations nor those using a turbulent mix model can explain fully the observed migration of shell-dopant material (titanium) into the core. Shell-dopant migration was observed via time-dependent, spatially integrated spectra, and spatially and spectrally resolved x-ray images of capsule implosions and resultant dopant emissions. The titanium emission was centrally peaked in narrowband x-ray images. In post-processed clean simulations, the peak titanium emission forms in a ring in self-emission images as the capsule implodes. Post-processed simulations with mix reproduce trends in time-dependent, spatially integrated spectra, as well having centrally peaked Ti emission in synthetic multiple monochromatic imager. However, mix simulations still do not transport Ti to the core as is observed in the experiment. This suggests that phenomena in addition to the turbulent mix must be responsible for the transport of Ti. Simple diffusion estimates are unable to explain the early Ti mix into the core. Mechanisms suggested for further study are capsule surface roughness, illumination non-uniformity, and shock entrainment.
Kamm, James R [Los Alamos National Laboratory; Shashkov, Mikhail J [Los Alamos National Laboratory
2009-01-01
Despite decades of development, Lagrangian hydrodynamics of strengthfree materials presents numerous open issues, even in one dimension. We focus on the problem of closing a system of equations for a two-material cell under the assumption of a single velocity model. There are several existing models and approaches, each possessing different levels of fidelity to the underlying physics and each exhibiting unique features in the computed solutions. We consider the case in which the change in heat in the constituent materials in the mixed cell is assumed equal. An instantaneous pressure equilibration model for a mixed cell can be cast as four equations in four unknowns, comprised of the updated values of the specific internal energy and the specific volume for each of the two materials in the mixed cell. The unique contribution of our approach is a physics-inspired, geometry-based model in which the updated values of the sub-cell, relaxing-toward-equilibrium constituent pressures are related to a local Riemann problem through an optimization principle. This approach couples the modeling problem of assigning sub-cell pressures to the physics associated with the local, dynamic evolution. We package our approach in the framework of a standard predictor-corrector time integration scheme. We evaluate our model using idealized, two material problems using either ideal-gas or stiffened-gas equations of state and compare these results to those computed with the method of Tipton and with corresponding pure-material calculations.
Russell, Christopher M P; Cuadra, Jorge; Owocki, Stanley P; Wang, Q Daniel; Hamaguchi, Kenji; Sugawara, Yasuharu; Pollock, Andrew M T; Kallman, Timothy R
2015-01-01
Colliding Wolf-Rayet (WR) winds produce thermal X-ray emission widely observed by X-ray telescopes. In wide WR+O binaries, such as WR 140, the X-ray flux is tied to the orbital phase, and is a direct probe of the winds' properties. In the Galactic center, $\\sim$30 WRs orbit the super massive black hole (SMBH) within $\\sim$10", leading to a smorgasbord of wind-wind collisions. To model the X-ray emission of WR 140 and the Galactic center, we perform 3D hydrodynamic simulations to trace the complex gaseous flows, and then carry out 3D radiative transfer calculations to compute the variable X-ray spectra. The model WR 140 RXTE light curve matches the data well for all phases except the X-ray minimum associated with periastron, while the model spectra agree with the RXTE hardness ratio and the shape of the Suzaku observations throughout the orbit. The Galactic center model of the Chandra flux and spectral shape match well in the region r$<$3", but the model flux falls off too rapidly beyond this radius.
DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)
Pan, Wenxiao; Daily, Michael; Baker, Nathan A.
2015-05-07
Background: The calculation of diffusion-controlled ligand binding rates is important for understanding enzyme mechanisms as well as designing enzyme inhibitors. Methods: We demonstrate the accuracy and effectiveness of a Lagrangian particle-based method, smoothed particle hydrodynamics (SPH), to study diffusion in biomolecular systems by numerically solving the time-dependent Smoluchowski equation for continuum diffusion. Unlike previous studies, a reactive Robin boundary condition (BC), rather than the absolute absorbing (Dirichlet) BC, is considered on the reactive boundaries. This new BC treatment allows for the analysis of enzymes with “imperfect” reaction rates. Results: The numerical method is first verified in simple systems and thenmore »applied to the calculation of ligand binding to a mouse acetylcholinesterase (mAChE) monomer. Rates for inhibitor binding to mAChE are calculated at various ionic strengths and compared with experiment and other numerical methods. We find that imposition of the Robin BC improves agreement between calculated and experimental reaction rates. Conclusions: Although this initial application focuses on a single monomer system, our new method provides a framework to explore broader applications of SPH in larger-scale biomolecular complexes by taking advantage of its Lagrangian particle-based nature.« less
COMPARING TWO NUMERICAL MODELS IN SIMULATING HYDRODYNAMICS AND SEDIMENT TRANSPORT AT A DUAL
US Army Corps of Engineers
The overall wave energy along this coast is mild with average breaker heights estimated to be 0.25-0.30 m with Delft University of Technology (Lesser et al. 2004) and has been applied to simulate coastal systems
Igor Sokolov
2014-03-20
A series of papers in the ISJAEE Journal on 'dam-free hydroelectric power station' concluded by paper: Zotyev, D. B., Alternative energy vs pseudo-science, ISJAEE. 2013. 8(130). P.131-136, is reviewed and commented. A comparison with the generally accepted energy conservation law in hydrodynamics reveals a disappointingly low scientific level of the reviewed papers (both pro- and contra- the dam-free concept), not excluding the published peer-reviewer reports. In the present version we emphasize that the ISJAEE journal published several papers, which neglect and reject the basic physical concepts, such as the Bernoulli integral, the energy conservation law in hydrodynamics, the wave function of photon and some others, with all these rejected concepts being far beyond the scientific scope of the journal. Some readers will be more concerned about the energy equation in hydrodynamics, in its theoretical form or in the Bernoulli integral form as being more traditional in technical hydromechanics. Some readers will be shocked with the statement that a photon does not possess the wave function. Overall, in this way or in that way, all readers will hardly stay unsurprised.
28th Symposium on Naval Hydrodynamics Pasadena, California, 12-17 September 2010
Mahesh, Krishnan
and Mechanics, University of Minnesota) ABSTRACT Flow around a marine propulsor under crashback operating Simulation of Marine Propulsors in Crashback Hyunchul Jang, Krishnan Mahesh (Aerospace Engineering equations are simulated in a rotating frame of reference that rotates with the propulsor. A non- dissipative
Thirumalai, Devarajan
2011-01-01
.1063/1.3593458] I. INTRODUCTION Semiflexible polymers are of interest in various fields of science and technology attention and the a)Present address: Institute for Physical Science and Technology, University of Maryland: Effects on semiflexible polymer dynamics Yann von Hansen,1 Michael Hinczewski,1,a) and Roland R. Netz2,b
Vol. 113 (2008) ACTA PHYSICA POLONICA A No. 2 Studies of the Hydrodynamic Properties
2008-01-01
ÂEinstein Condensate of 87 Rb Atoms in a Magnetic Trap F. Bylickia,b , W. Gawlika,c , W. JastrzeÂ¸bskia,d , A. Nogaa University Reymonta 4, 30-057 KrakÂ´ow, Poland d Institute of Physics, Polish Academy of Sciences al. Lotnik and the experimental procedure lead- ing to production of the BoseÂEinstein condensate of 87 Rb atoms. Basic
KIVA--Hydrodynamics Model for Chemically Reacting Flow with Spray - Energy
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Homesum_a_epg0_fpd_mmcf_m.xls" ,"Available from WebQuantityBonneville Power Administration would likeUniverseIMPACT EVALUATIONIntroducingJobs2015Administration shows off theKIVA
Galactic scale gas flows in colliding galaxies: 3-Dimensional, N-body/hydrodynamics experiments
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AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Homesum_a_epg0_fpd_mmcf_m.xls" ,"Available from WebQuantityBonneville Power Administration would likeUniverse (Journal Article)ForthcomingGENERAL ASSIGNMENT KNOW09-001.docGainache.
K. V. Ramesh; R. Thaokar; J. Ravi Prakash; R. Prabhakar
2015-01-29
The dynamics of adhesion of a spherical micro-particle to a ligand-coated wall, in shear flow, is studied using a Langevin equation that accounts for thermal fluctuations, hydrodynamic interactions and adhesive interactions. Contrary to the conventional assumption that thermal fluctuations play a negligible role at high P$\\acute{e}$clet numbers, we find that for particles with low surface densities of receptors, rotational diffusion caused by fluctuations about the flow and gradient directions aids in bond formation, leading to significantly greater adhesion on average, compared to simulations where thermal fluctuations are completely ignored. The role of wall hydrodynamic interactions on the steady state motion of a particle, when the particle is close to the wall, has also been explored. At high P$\\acute{e}$clet numbers, the shear induced force that arises due to the stresslet part of the Stokes dipole, plays a dominant role, reducing the particle velocity significantly, and affecting the states of motion of the particle. The coupling between the translational and rotational degrees of freedom of the particle, brought about by the presence of hydrodynamic interactions, is found to have no influence on the binding dynamics. On the other hand, the drag coefficient, which depends on the distance of the particle from the wall, plays a crucial role at low rates of bond formation. A significant difference in the effect of both the shear force and the position dependent drag force, on the states of motion of the particle, is observed when the P$\\acute{e}$let number is small.
Bevelhimer, Mark S; Coutant, Charles C
2006-07-01
Dissolved oxygen (DO) in rivers is a common environmental problem associated with hydropower projects. Approximately 40% of all FERC-licensed projects have requirements to monitor and/or mitigate downstream DO conditions. Most forms of mitigation for increasing DO in dam tailwaters are fairly expensive. One area of research of the Department of Energy's Hydropower Program is the development of advanced turbines that improve downstream water quality and have other environmental benefits. There is great interest in being able to predict the benefits of these modifications prior to committing to the cost of new equipment. In the case of turbine replacement or modification, there is a need for methods that allow us to accurately extrapolate the benefits derived from one or two turbines with better design to the replacement or modification of all turbines at a site. The main objective of our study was to demonstrate a modeling approach that integrates the effects of flow and water quality dynamics with fish bioenergetics to predict DO mitigation effectiveness over long river segments downstream of hydropower dams. We were particularly interested in demonstrating the incremental value of including a fish growth model as a measure of biological response. The models applied are a suite of tools (RMS4 modeling system) originally developed by the Tennessee Valley Authority for simulating hydrodynamics (ADYN model), water quality (RQUAL model), and fish growth (FISH model) as influenced by DO, temperature, and available food base. We parameterized a model for a 26-mile reach of the Caney Fork River (Tennessee) below Center Hill Dam to assess how improvements in DO at the dam discharge would affect water quality and fish growth throughout the river. We simulated different types of mitigation (i.e., at the turbine and in the reservoir forebay) and different levels of improvement. The model application successfully demonstrates how a modeling approach like this one can be used to assess whether a prescribed mitigation is likely to meet intended objectives from both a water quality and a biological resource perspective. These techniques can be used to assess the tradeoffs between hydropower operations, power generation, and environmental quality.
Limousin, Marceau; Sommer-Larsen, Jesper; Milvang-Jensen, Bo [Dark Cosmology Centre, Niels Bohr Institute, University of Copenhagen, Juliane Maries Vej 30, 2100 Copenhagen (Denmark); Natarajan, Priyamvada [Astronomy Department, Yale University, P.O. Box 208101, New Haven, CT 06520-8101 (United States)], E-mail: marceau.limousin@oamp.fr
2009-05-10
We analyze high-resolution, N-body hydrodynamical simulations of fiducial galaxy clusters to probe tidal stripping of the dark matter subhalos. These simulations include a prescription for star formation allowing us to track the fate of the stellar component as well. We investigate the effect of tidal stripping on cluster galaxies hosted in these dark matter subhalos as a function of projected cluster-centric radius. To quantify the extent of the dark matter halos of cluster galaxies, we introduce the half-mass radius r {sub 1/2} as a diagnostic, and study its evolution with projected cluster-centric distance R as a function of redshift. We find a well-defined trend for (r {sub 1/2}, R): the closer the galaxies are to the center of the cluster, the smaller the half-mass radius. Interestingly, this trend is inferred in all redshift frames examined in this work ranging from z = 0 to z = 0.7. At z = 0, galaxy halos in the central regions of clusters are found to be highly truncated, with the most compact half-mass radius of 10 kpc. We also find that r {sub 1/2} depends on luminosity and we present scaling relations of r {sub 1/2} with galaxy luminosity. The corresponding total mass of the cluster galaxies is also found to increase with projected cluster-centric distance and luminosity, but with more scatter than the (r {sub 1/2}, R) trend. Comparing the distribution of stellar mass to total mass for cluster galaxies, we find that the dark matter component is preferentially stripped, whereas the stellar component is much less affected by tidal forces. We compare these results with galaxy-galaxy lensing probes of r {sub 1/2} and find qualitative agreement. Future surveys with space-based telescopes such as DUNE and SNAP, that combine wide-field and high-resolution imaging, will be able to probe the predicted (r {sub 1/2}, R) relation observationally.
Day, Robert A. (Livermore, CA); Conti, Armond E. (San Jose, CA)
1980-01-01
An improved probe for in-service ultrasonic inspection of long lengths of a workpiece, such as small diameter tubing from the interior. The improved probe utilizes a conventional transducer or transducers configured to inspect the tubing for flaws and/or wall thickness variations. The probe utilizes a hydraulic technique, in place of the conventional mechanical guides or bushings, which allows the probe to move rectilinearly or rotationally while preventing cocking thereof in the tube and provides damping vibration of the probe. The probe thus has lower friction and higher inspection speed than presently known probes.
K. J. Eskola; H. Niemi; R. Paatelainen
2015-09-09
We introduce an event-by-event pQCD + saturation + hydro ("EKRT") framework for high-energy heavy-ion collisions, where we compute the produced fluctuating QCD-matter energy densities from next-to-leading order (NLO) perturbative QCD (pQCD) using saturation to control soft particle production, and describe the space-time evolution of the QCD matter with viscous hydrodynamics, event by event (EbyE). We compare the computed centrality dependence of hadronic multiplicities, p_T spectra and flow coefficients v_n against LHC and RHIC data. We compare also the computed EbyE probability distributions of relative fluctuations of v_n, as well as correlations of 2 and 3 event-plane angles, with LHC data. Our systematic multi-energy and -observable analysis not only tests the initial state calculation and applicability of hydrodynamics, but also makes it possible to constrain the temperature dependence of the shear viscosity-to-entropy ratio, eta/s(T), of QCD matter in its different phases. Remarkably, we can describe all these different flow observables and correlations consistently with eta/s(T) that is independent of the collision energy.
Wang, Taiping; Khangaonkar, Tarang; Long, Wen; Gill, Gary A.
2014-02-07
In recent years, with the rapid growth of global energy demand, the interest in extracting uranium from seawater for nuclear energy has been renewed. While extracting seawater uranium is not yet commercially viable, it serves as a “backstop” to the conventional uranium resources and provides an essentially unlimited supply of uranium resource. With recent advances in seawater uranium extraction technology, extracting uranium from seawater could be economically feasible when the extraction devices are deployed at a large scale (e.g., several hundred km2). There is concern however that the large scale deployment of adsorbent farms could result in potential impacts to the hydrodynamic flow field in an oceanic setting. In this study, a kelp-type structure module was incorporated into a coastal ocean model to simulate the blockage effect of uranium extraction devices on the flow field. The module was quantitatively validated against laboratory flume experiments for both velocity and turbulence profiles. The model-data comparison showed an overall good agreement and validated the approach of applying the model to assess the potential hydrodynamic impact of uranium extraction devices or other underwater structures in coastal oceans.
Hu, Huosheng
fish Robotic design SimulationObjectives Hydrodynamic testsThe main objective of the SHOAL project is to design and develop three The hydrodynamic component will simulate fish ICT call: Project contract number in this consortium, the University of ESSEX has successfully built the advanced robotic fish (shown in the left
Gorban, Alexander N.
of Hydrodynamics: A Soluble Example Alexander N. Gorban and Iliya V. Karlin* Computing Center, Russian Academy of Sciences, Krasnoyarsk-36, 660036 Russian Federation (Received 4 January 1996) The Chapman-Enskog series, a possibility to compute a solution as a formal series in powers of Knudsen number e (where e is a ratio between
Ohl, Claus-Dieter
of a standing acoustic wave. An ordinary dif- ferential equation (ODE) approach, based on a balance be- tween Acoustic and Hydrodynamic Forces Compete Judith Rensen,1 Dennis Bosman,1 Jacques Magnaudet,2 Claus to study the effect of acoustic forces on individual bubbles in shear flows have been carried out
Chadima, Pavel; Harmanec, Petr; Wolf, Marek; Firt, Roman; Ruzdjak, Domagoj; Bozic, Hrvoje; Koubsky, Pavel
2011-07-15
H{alpha} emission V/R variations caused by discontinuous mass transfer in interacting binaries with a rapidly rotating accreting star are modeled qualitatively for the first time. The program ZEUS-MP was used to create a non-linear three-dimensional hydrodynamical model of a development of a blob of gaseous material injected into an orbit around a star. It resulted in the formation of an elongated disk with a slow prograde revolution. The LTE radiative transfer program SHELLSPEC was used to calculate the H{alpha} profiles originating in the disk for several phases of its revolution. The profiles have the form of a double emission and exhibit V/R and radial velocity variations. However, these variations should be a temporal phenomenon since imposing a viscosity in the given model would lead to a circularization of the disk and fading-out of the given variations.
Mueller, Bernhard; Janka, Hans-Thomas; Marek, Andreas, E-mail: bjmuellr@mpa-garching.mpg.de, E-mail: thj@mpa-garching.mpg.de [Max-Planck-Institut fuer Astrophysik, Karl-Schwarzschild-Str. 1, D-85748 Garching (Germany)
2012-09-01
We present the first two-dimensional general relativistic (GR) simulations of stellar core collapse and explosion with the COCONUT hydrodynamics code in combination with the VERTEX solver for energy-dependent, three-flavor neutrino transport, using the extended conformal flatness condition for approximating the space-time metric and a ray-by-ray-plus ansatz to tackle the multi-dimensionality of the transport. For both of the investigated 11.2 and 15 M{sub Sun} progenitors we obtain successful, though seemingly marginal, neutrino-driven supernova explosions. This outcome and the time evolution of the models basically agree with results previously obtained with the PROMETHEUS hydro solver including an approximative treatment of relativistic effects by a modified Newtonian potential. However, GR models exhibit subtle differences in the neutrinospheric conditions compared with Newtonian and pseudo-Newtonian simulations. These differences lead to significantly higher luminosities and mean energies of the radiated electron neutrinos and antineutrinos and therefore to larger energy-deposition rates and heating efficiencies in the gain layer with favorable consequences for strong nonradial mass motions and ultimately for an explosion. Moreover, energy transfer to the stellar medium around the neutrinospheres through nucleon recoil in scattering reactions of heavy-lepton neutrinos also enhances the mentioned effects. Together with previous pseudo-Newtonian models, the presented relativistic calculations suggest that the treatment of gravity and energy-exchanging neutrino interactions can make differences of even 50%-100% in some quantities and is likely to contribute to a finally successful explosion mechanism on no minor level than hydrodynamical differences between different dimensions.
Matthias Stute; Raghvendra Sahai
2007-04-17
In papers I and II in this series, we presented hydrodynamical simulations of jet models with parameters representative of the symbiotic system MWC 560. These were simulations of a pulsed, initially underdense jet in a high density ambient medium. Since the pulsed emission of the jet creates internal shocks and since the jet velocity is very high, the jet bow shock and the internal shocks are heated to high temperatures and should therefore emit X-ray radiation. In this paper, we investigate in detail the X-ray properties of the jets in our models. We have focused our study on the total X-ray luminosity and its temporal variability, the resulting spectra and the spatial distribution of the emission. Temperature and density maps from our hydrodynamical simulations with radiative cooling presented in the second paper are used together with emissivities calculated with the atomic database ATOMDB. The jets in our models show extended and variable X-ray emission which can be characterized as a sum of hot and warm components with temperatures that are consistent with observations of CH Cyg and R Aqr. The X-ray spectra of our model jets show emission line features which correspond to observed features in the spectra of CH Cyg. The innermost parts of our pulsed jets show iron line emission in the 6.4 - 6.7 keV range which may explain such emission from the central source in R Aqr. We conclude that MWC 560 should be detectable with Chandra or XMM-Newton, and such X-ray observations will provide crucial for understanding jets in symbiotic stars.
Sokolov, Igor
2013-01-01
A series of papers in the ISJAEE Journal on 'dam-free hydroelectric power station' concluded by paper: Zotyev, D. B., 'Alternative energy vs pseudo-science', ISJAEE. 2013. 8(130). P.131-136, is reviewed and commented. A comparison with the generally accepted energy conservation law in hydrodynamics reveals a disappointingly low scientific level of the reviewed papers (both pro- and contra- the dam-free concept), not excluding the published peer-reviewer reports.
Pan, Wenxiao; Li, Dongsheng; Tartakovsky, Alexandre M.; Ahzi, Said; Khraisheh, Marwan; Khaleel, Mohammad A.
2013-09-06
We present a new smoothed particle hydrodynamics (SPH) model for friction stir welding (FSW). FSW has found broad commercial application in the marine, aerospace, rail and automotive industries. Development of the FSW process for each new application, however, has remained largely empirical. Few established numerical modeling techniques have been developed that can explain and predict important features of the process physics involved in FSW. This is particularly true in the areas of material ?ow, mixing mechanisms, and void formation. In this paper we present a novel modeling approach to simulate FSW that may have signi?cant advantages over current ?nite element or ?nite di?erence based methods. Unlike traditional grid-based methods, Lagrangian particle methods such as SPH can simulate the dynamics of interfaces, large material deformations, and the material’s strain and temperature history without employing complex tracking schemes. Three-dimensional simulations of FSW on AZ31 Mg alloy are presented. Numerical results are in a close quantitative agreement with experimental observations.
Sizyuk, V.; Hassanein, A.; Morozov, V.; Sizyuk, T.; Mathematics and Computer Science
2007-01-16
The HEIGHTS integrated model has been developed as an instrument for simulation and optimization of laser-produced plasma (LPP) sources relevant to extreme ultraviolet (EUV) lithography. The model combines three general parts: hydrodynamics, radiation transport, and heat conduction. The first part employs a total variation diminishing scheme in the Lax-Friedrich formulation (TVD-LF); the second part, a Monte Carlo model; and the third part, implicit schemes with sparse matrix technology. All model parts consider physical processes in three-dimensional geometry. The influence of a generated magnetic field on laser plasma behavior was estimated, and it was found that this effect could be neglected for laser intensities relevant to EUV (up to {approx}10{sup 12} W/cm{sup 2}). All applied schemes were tested on analytical problems separately. Benchmark modeling of the full EUV source problem with a planar tin target showed good correspondence with experimental and theoretical data. Preliminary results are presented for tin droplet- and planar-target LPP devices. The influence of three-dimensional effects on EUV properties of source is discussed.
MHK Projects/Marine Hydrodynamics Laboratory at the University of Michigan
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Sweetman, Bert
to first-order wave energy, a low-frequency contribution due to pitch, and a still lower frequency" of the NSF-sponsored Offshore Technology Research Center (OTRC), centered at Texas A&M University
M. I. Krivoruchenko; B. V. Martemyanov
2015-03-04
If strange matter is absolutely stable, the ordinary nuclei decay to strangelets, while neutron stars convert into strange stars. Lifetimes of the ordinary nuclei are constrained experimentally to be above $\\sim 10^{33}$ years, while lifetimes of the metastable neutron stars depend on the neutron star masses and can exceed the age of the Universe. As a consequence, the neutron stars and the strange stars can coexist in the Universe. We point out that numerical simulations of the conversion of neutron stars to strange stars, performed by M. Herzog and F. K. Roepke in Phys. Rev. D 84, 083002 (2011) [arXiv:1109.0539], are focused on a region in the parameter space of strange matter, in which low-mass neutron stars and strange stars are coexistent, whereas massive neutron stars are unstable and short lived on an astronomical timescale.
Mueller, Bernhard; Janka, Hans-Thomas [Max-Planck-Institut fuer Astrophysik, Karl-Schwarzschild-Str. 1, D-85748 Garching (Germany); Dimmelmeier, Harald, E-mail: bjmuellr@mpa-garching.mpg.d, E-mail: thj@mpa-garching.mpg.d, E-mail: harrydee@mpa-garching.mpg.d [Physics Department, Aristotle University of Thessaloniki, GR-54124 Thessaloniki (Greece)
2010-07-15
We present a new general relativistic code for hydrodynamical supernova simulations with neutrino transport in spherical and azimuthal symmetry (one dimension and two dimensions, respectively). The code is a combination of the COCONUT hydro module, which is a Riemann-solver-based, high-resolution shock-capturing method, and the three-flavor, fully energy-dependent VERTEX scheme for the transport of massless neutrinos. VERTEX integrates the coupled neutrino energy and momentum equations with a variable Eddington factor closure computed from a model Boltzmann equation and uses the 'ray-by-ray plus' approximation in two dimensions, assuming the neutrino distribution to be axially symmetric around the radial direction at every point in space, and thus the neutrino flux to be radial. Our spacetime treatment employs the Arnowitt-Deser-Misner 3+1 formalism with the conformal flatness condition for the spatial three metric. This approach is exact for the one-dimensional case and has previously been shown to yield very accurate results for spherical and rotational stellar core collapse. We introduce new formulations of the energy equation to improve total energy conservation in relativistic and Newtonian hydro simulations with grid-based Eulerian finite-volume codes. Moreover, a modified version of the VERTEX scheme is developed that simultaneously conserves energy and lepton number in the neutrino transport with better accuracy and higher numerical stability in the high-energy tail of the spectrum. To verify our code, we conduct a series of tests in spherical symmetry, including a detailed comparison with published results of the collapse, shock formation, shock breakout, and accretion phases. Long-time simulations of proto-neutron star cooling until several seconds after core bounce both demonstrate the robustness of the new COCONUT-VERTEX code and show the approximate treatment of relativistic effects by means of an effective relativistic gravitational potential as in PROMETHEUS-VERTEX to be remarkably accurate in spherical symmetry.
DIMITRI GIDASPOW
1997-08-15
The objective of this study is to develop a predictive experimentally verified computational fluid dynamic (CFD) three phase model. It predicts the gas, liquid and solid hold-ups (volume fractions) and flow patterns in the industrially important bubble-coalesced (churn-turbulent) regime. The input into the model can be either particulate viscosities as measured with a Brookfield viscometer or effective restitution coefficient for particles. A combination of x-ray and {gamma}-ray densitometers was used to measure solid and liquid volume fractions. There is a fair agreement between the theory and the experiment. A CCD camera was used to measure instantaneous particle velocities. There is a good agreement between the computed time average velocities and the measurements. There is an excellent agreement between the viscosity of 800 {micro}m glass beads obtained from measurement of granular temperature (random kinetic energy of particles) and the measurement using a Brookfield viscometer. A relation between particle Reynolds stresses and granular temperature was found for developed flow. Such measurement and computations gave a restitution coefficient for a methanol catalyst to be about 0.9. A transient, two-dimensional hydrodynamic model for production of methanol from syn-gas in an Air Products/DOE LaPorte slurry bubble column reactor was developed. The model predicts downflow of catalyst at the walls and oscillatory particle and gas flow at the center, with a frequency of about 0.7 Hertz. The computed temperature variation in the rector with heat exchangers was only about 5 K, indicating good thermal management. The computed slurry height, the gas holdup and the rate of methanol production agree with LaPorte's reported data. Unlike the previous models in the literature, this model computes the gas and the particle holdups and the particle rheology. The only adjustable parameter in the model is the effective particle restitution coefficient.
Takiwaki, Tomoya; Kotake, Kei; Suwa, Yudai
2012-04-20
We present numerical results on three-dimensional (3D) hydrodynamic core-collapse simulations of an 11.2 M{sub Sun} star. By comparing one-dimensional (1D) and two-dimensional (2D) results with those of 3D, we study how the increasing spacial multi-dimensionality affects the postbounce supernova dynamics. The calculations were performed with an energy-dependent treatment of the neutrino transport that is solved by the isotropic diffusion source approximation scheme. In agreement with previous study, our 1D model does not produce explosions for the 11.2 M{sub Sun} star, while the neutrino-driven revival of the stalled bounce shock is obtained in both the 2D and 3D models. The standing accretion-shock instability (SASI) is observed in the 3D models, in which the dominant mode of the SASI is bipolar (l = 2) with its saturation amplitudes being slightly smaller than 2D. By performing a tracer-particle analysis, we show that the maximum residency time of material in the gain region becomes longer in 3D than in 2D due to non-axisymmetric flow motions, which is one of advantageous aspects of 3D models to obtain neutrino-driven explosions. Our results show that convective matter motions below the gain radius become much more violent in 3D than in 2D, making the neutrino luminosity larger for 3D. Nevertheless, the emitted neutrino energies are made smaller due to the enhanced cooling. Our results indicate whether these advantages for driving 3D explosions could or could not overwhelm the disadvantages is sensitive to the employed numerical resolutions. An encouraging finding is that the shock expansion tends to become more energetic for models with finer resolutions. To draw a robust conclusion, 3D simulations with much higher numerical resolutions and with more advanced treatment of neutrino transport and of gravity are needed, which could be practicable by utilizing forthcoming Petaflops-class supercomputers.
Formation Interuniversitaire de Physique Hydrodynamics
Balbus, Steven
of Partial Differential Equations . . 69 4.8.2 The Steepening of Acoustic Waves . . . . . . . . . . . 70 4 . . . . . . . . . . . . . . . . . . . . . . . . . . . 66 4.8 Nonlinear Acoustic Waves . . . . . . . . . . . . . . . . . . . . 69 4.8.1 Quasilinear Theory Wave . . . . . . . . . . . . . . . . . 84 4.10.2 Derivation of the Korteweg-de Vries Equation
Hydrodynamics of aqueous humor outflow
Overby, Darryl Ray, 1974-
2002-01-01
Primary open-angle glaucoma (POAG) is a leading cause of irreversible blindness resulting from elevated intraocular pressure caused by a pathologic increase in the resistance to aqueous humor outflow from the eye. Currently, ...
Higher order anisotropies in hydrodynamics
M. Csanad; A. Szabo; S. Lokos; A. Bagoly
2015-04-29
In the last years it has been revealed that if measuring relative to higher order event planes $\\Psi_n$, higher order flow coefficients $v_n$ for $n>2$ can be measured. It also turned out that Bose-Einstein (HBT) correlation radii also show 3rd order oscillations if measured versus the third order event plane $\\Psi_3$. In this paper we investigate how these observables can be described via analytic hydro solutions and hydro parameterizations. We also investigate the time evolution of asymmetry coefficients and the mixing of velocity field asymmetries and density asymmetries.
Higher order anisotropies in hydrodynamics
Csanad, M; Lokos, S; Bagoly, A
2015-01-01
In the last years it has been revealed that if measuring relative to higher order event planes $\\Psi_n$, higher order flow coefficients $v_n$ for $n>2$ can be measured. It also turned out that Bose-Einstein (HBT) correlation radii also show 3rd order oscillations if measured versus the third order event plane $\\Psi_3$. In this paper we investigate how these observables can be described via analytic hydro solutions and hydro parameterizations. We also investigate the time evolution of asymmetry coefficients and the mixing of velocity field asymmetries and density asymmetries.
Thomas, Peter
. Abstract The Millennium Gas project aims to undertake smoothed-particle hydrodynamic-ray surveys (170 clusters with kTsl > 3 keV). This paper looks at the hot gas and stellar fractions-core systems but are successful in matching the hot gas profiles of non-cool-core clusters. Although
Nesewich, J.P.; Gracey, C.M. [Los Alamos National Lab., NM (United States)
1982-04-01
The Aerojet Energy Conversion Company, under contract to the Los Alamos National Laboratory, US Department of Energy, has constructed and tested a mobile geothermal well-site test unit at the Mercer 2 well in South Brawley, California (Imperial Valley). The equipment controlled, monitored, and recorded all process conditions of single- and dual-flash power cycles. Single- and two-phase flashed brine effluents were flowed through piping component test sections to provide hydrodynamic/kinetic data for scale formation. The unit operated at flowrates in excess of 200 gpm and is designed to accommodate flowrates up to 300 gpm. Primary scale formations encountered were those of Pbs, Fe{sub 2} (OH){sub 3}Cl (iron hydroxychloride), iron chlorides, and non-crystalline forms Of SiO{sub 2}. The formation of iron hydroxychloride was due to the unusually high concentration of iron in the wellhead brine (5000 mg/1).
Piero Chiarelli
2013-05-20
In the present paper the gas, liquid and solid phases made of structureless particles, are visited to the light of the quantum stochastic hydrodynamic analogy (SQHA). The SQHA shows that the open quantum mechanical behavior is maintained on a distance shorter than the theory-defined quantum correlation length (lc). When, the physical length of the problem is larger than lc, the model shows that the quantum (potential) interactions may have a finite range of interaction maintaining the non-local behavior on a finite distance quantum non-locality length lq. The present work shows that when the mean molecular distance is larger than the quantum non-locality length we have a classical phases (gas and van der Waals liquids) while when the mean molecular distance becomes smaller than lq or than lc we have phases such as the solid crystal or the superfluid one, respectively, that show quantum characteristics. The model agrees with Lindemann empirical law (and explains it), for the mean square deviation of atom from the equilibrium position at melting point of crystal, and shows a connection between the maximum density at the He lambda point and that one near the water-ice solidification point.
EINDHOVEN UNIVERSITY OF TECHNOLOGY Department of Mathematics and Computer Science
Eindhoven, Technische Universiteit
, Slovenia 4Newcastle University, United Kingdom 5Deltares, Delft, The Netherlands 6Budapest University is rather complex. The flow behaviour is measured by various instruments and hence a thorough hydrodynamic hydraulic applications, such as water-distribution networks, storm-water and sewage systems, fire
Unsteady propeller hydrodynamics by Dirk H. Renick.
Renick, Dirk Hampton, 1970-
2001-01-01
One of the main problem affecting modern propulsor design engineers is the ability to quantitatively predict unsteady propeller forces for modern, multi-blade row, ducted propulsors operating in highly contracting flowfields. ...
Canonical equations of ideal magnetic hydrodynamics
Gorskii, V.B.
1987-07-01
Ideal magnetohydrodynamics is used to consider a general class of adiabatic flow in magnetic liquids. Two invariants of the canonical equations of motion--Hamiltonian and Lagrangian--are determined in terms of the canonical variables by using the approximate variational formulations. The resulting model describes adiabatic three-dimensional flow of a nonviscous compressible liquid with ideal electric conductivity and zero heat conductivity. A Clebsch transformation is used to arrive at a form of the Lagrange-Cauchy integral for a vortex flow.
The Hydrodynamics of Chemical Cues Among
on the fluid velocity and flow regime, released chemicals are transported via dif- fusion, laminar advection mediated processes must consider fluid properties and flow because the fluid environment determines, Atlanta, Georgia 30332; email: dwebster@ce.gatech.edu Annu. Rev. Fluid Mech. 2009. 41:7390 First
Vortex-Based Aero- and Hydrodynamic Estimation
Hemati, Maziar Sam
2013-01-01
1. The strength of a vortex tube is uniform along the tube.3. The strength of a vortex tube is invariant in time. Theof Vortex Ring Formation at the Edge of a Circular Tube. ”
Hydrodynamic phonon transport in suspended graphene
Lee, Sangyeop
Recent studies of thermal transport in nanomaterials have demonstrated the breakdown of Fourier’s law through observations of ballistic transport. Despite its unique features, another instance of the breakdown of Fourier’s ...
Hydrodynamic Exchange in Estuarine Perimeter Habitats
HSU, KEVIN KAI-WIN
2013-01-01
L. and M. Li. 2006. Tidal energy fluxes and dissipation infrictional losses of tidal energy at the bed. In contrast,even though wind and tidal energy inputs can be comparable
The hydrodynamics of water-walking arthropods
Bush, John W. M.
We present the results of a combined experimental and theoretical investigation of the dynamics of water-walking insects and spiders. Using high-speed videography, we describe their numerous gaits, some analogous to those ...
Galilean Anomalies and Their Effect on Hydrodynamics
Akash Jain
2015-09-18
We extend the null background construction of [arXiv:1505.05677,arXiv:1509.04718] to include torsion and a conserved spin current, and use it to study gauge and gravitational anomalies in Galilean theories coupled to torsional Newton-Cartan backgrounds. We establish that the relativistic anomaly inflow mechanism with an appropriately modified anomaly polynomial, can be used to generate these anomalies. Similar to relativistic case, we find that Galilean anomalies also survive only in even dimensions. Further, these anomalies only effect the gauge and rotational symmetries of a Galilean theory; in particular the Milne boost symmetry remains non-anomalous. We also extend the transgression machinery used in relativistic fluids to fluids on null backgrounds, and use it to determine how these anomalies affect the constitutive relations of a Galilean fluid. Unrelated to Galilean fluids, we propose an analogue of the off-shell second law of thermodynamics for relativistic fluids introduced by [arXiv:1106.0277], to include torsion and a conserved spin current in Vielbein formalism. Interestingly, we find that even in absense of spin and torsion the entropy currents in two formalisms are different; while the usual entropy current gets a contribution from gravitational anomaly, the entropy current in Vielbein formalism does not have any anomaly induced part.
Hydrodynamic Waves in an Anomalous Charged Fluid
Abbasi, Navid; Rezaei, Zahra
2015-01-01
We study the collective excitations in a relativistic fluid with an anomalous conserved charge. In $3+1$ dimensions, in addition to two ordinary sound modes we find two propagating modes in presence of an external magnetic field: one with a velocity proportional to the coefficient of gauge-gravitational anomaly coefficient and the other with a velocity which depends on both chiral anomaly and the gauge gravitational anomaly coefficients. While the former is the Chiral Alfv\\'en wave recently found in arXiv:1505.05444, the latter is a new type of collective excitations originated from the density fluctuations. We refer to these modes as the Type-M and Type-D chiral Alfv\\'en waves respectively. We show that the Type-M Chiral Alfv\\'en mode is split into two chiral Alfv\\'en modes when taking into account the effect of dissipation processes in the fluid. In 1+1 dimensions we find only one propagating mode associated with the anomalous effects. We explicitly compute the velocity of this wave and show that in contras...
13.021 Marine Hydrodynamics, Fall 2001
Yue, Dick Kau-Ping
The fundamentals of fluid mechanics are developed in the context of naval architecture and ocean science and engineering. Transport theorem and conservation principles. Navier-Stokes' equation. Dimensional analysis. Ideal ...
Nonlocal kinetic equation: integrable hydrodynamic reductions, symmetries
, Troitsk, Moscow Region, Russia Lebedev Physical Institute, Russian Academy of Sciences, Moscow § SISSA, Trieste, Italy, and Institute of Metal Physics, Urals Division of Russian Academy of Sciences, Ekaterinburg, Russia We study a new class of nonlinear kinetic equations recently derived in the context
MHD duct flows under hydrodynamic “slip” condition
Smolentsev, S.
2009-01-01
Kluwer, Dordrecht (1990) 13. Hartmann, J. : Hg-dynamics. I.the insulating wall: (1) Hartmann ?ow; (2) fully developed ?Additionally to the Hartmann number (H a), a new
Galilean Anomalies and Their Effect on Hydrodynamics
Jain, Akash
2015-01-01
We extend the null background construction of [arXiv:1505.05677,arXiv:1509.04718] to include torsion and a conserved spin current, and use it to study gauge and gravitational anomalies in Galilean theories coupled to torsional Newton-Cartan backgrounds. We establish that the relativistic anomaly inflow mechanism with an appropriately modified anomaly polynomial, can be used to generate these anomalies. Similar to relativistic case, we find that Galilean anomalies also survive only in even dimensions. Further, these anomalies only effect the gauge and rotational symmetries of a Galilean theory; in particular the Milne boost symmetry remains non-anomalous. We also extend the transgression machinery used in relativistic fluids to fluids on null backgrounds, and use it to determine how these anomalies affect the constitutive relations of a Galilean fluid. Unrelated to Galilean fluids, we propose an analogue of the off-shell second law of thermodynamics for relativistic fluids introduced by [arXiv:1106.0277], to i...
The hydrodynamics of aspherical twowind configurations
Icke, Vincent
and the fusion flame flickers irregularly. During this soÂcalled ``AGB phase'', the outer envelope of the star@strw.LeidenUniv.nl 1. Stardeath The life of a star is an incessant struggle between gravity and gas pressure. The selfÂgravity of a star's mass pulls it together; the star doesn't collapse as long as it can find a source
Hydrodynamics of prey capture in sharks: effects
Lauder, George V.
plagiosum, during suction feeding on the substrate and in the water column. Empirical results confirmed by the majority of aquatic vertebrates (Lauder & Shaffer 1993). It involves rapidly expanding the oral cavity column, the ability of organisms to use substrates to enhance feeding performance has not been
Massachusetts Institute of Technology Hydrodynamics | Open Energy
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Sandia National Laboratories Hydrodynamics | Open Energy Information
AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page on Google Bookmark EERE: Alternative Fuels Data Center Home Page on QA:QA J-E-1 SECTION J APPENDIX ECoop Inc Jump to:Newberg,EnergyEastCarbon DevelopmentValley
Dual Axis Radiographic Hydrodynamic Test Facility
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Homesum_a_epg0_fpd_mmcf_m.xls" ,"Available from WebQuantity of NaturalDukeWakefieldSulfateSciTechtail.Theory ofDid you not find what you wereDisclaimers WelcomeResearch >DOE Office
Universal formulae for thermoelectric transport with magnetic field and disorder
Amoretti, Andrea
2015-01-01
We obtain explicit expressions for the thermoelectric transport coefficients of a strongly coupled, planar medium in the presence of an orthogonal magnetic field and disorder. The computations are performed within the gauge/gravity framework, however we propose and argue for a possible universal relevance of the results relying on comparisons and extensions of previous hydrodynamical analyses and experimental data.
King, Michael J; Bredehoeft, John D., Dr.
2010-09-03
Inyo County completed the first year of the U.S. Department of Energy Grant Agreement No. DE-RW0000233. This report presents the results of research conducted within this Grant agreement in the context of Inyo County's Yucca Mountain oversight program goals and objectives. The Hydrodynamics Group, LLC prepared this report for Inyo County Yucca Mountain Repository Assessment Office. The overall goal of Inyo County's Yucca Mountain research program is the evaluation of far-field issues related to potential transport, by ground water, of radionuclide into Inyo County, including Death Valley, and the evaluation of a connection between the Lower Carbonate Aquifer (LCA) and the biosphere. Data collected within the Grant is included in interpretive illustrations and discussions of the results of our analysis. The centeral elements of this Grant prgoram was the drilling of exploratory wells, geophysical surveys, geological mapping of the Southern Funeral Mountain Range. The cullimination of this research was 1) a numerical ground water model of the Southern Funeral Mountain Range demonstrating the potential of a hydraulic connection between the LCA and the major springs in the Furnace Creek area of Death Valley, and 2) a numerical ground water model of the Amargosa Valley to evaluate the potential for radionuclide transport from Yucca Mountain to Inyo County, California. The report provides a description of research and activities performed by The Hydrodynamics Group, LLC on behalf of Inyo County, and copies of key work products in attachments to this report.
Mechatronics Engineering Program, SabanciUniversity,
Peles, Yoav
, Rensselaer Polytechnic Institute, Troy, NY 12180 Hydrodynamic Characteristics of Crossflow over MEMS-Based Pillars A parametric study was performed to reveal the hydrodynamic processes controlling crossflow over, DNA siev- ing, DNA analysis, and mixing. Since objects in crossflow perturb the flow field
Free boundary problem and hydrodynamic limit Jeremy Quastel
Quastel, Jeremy
problem comes up in nuclear waste management 1 . Radioactive waste is placed in a container and buried
Transport Coefficients for Holographic Hydrodynamics at Finite Energy Scale
Xian-Hui Ge; Hong-Qiang Leng; Li Qing Fang; Guo-Hong Yang
2014-08-19
We investigate the relations between black hole thermodynamics and holographic transport coefficients in this paper. The formulae for DC conductivity and diffusion coefficient are verified for electrically single-charged black holes. We examine the correctness of the proposed expressions by taking charged dilatonic and single-charged STU black holes as two concrete examples, and compute the flows of conductivity and diffusion coefficient by solving the linear order perturbation equations. We then check the consistence by evaluating the Brown-York tensor at a finite radial position. Finally, we find that the retarded Green functions for the shear modes can be expressed easily in terms of black hole thermodynamic quantities and transport coefficients.