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)...
Jacquez, Edward B [Los Alamos National Laboratory
2008-01-01T23:59:59.000Z
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.
NONE
1995-08-01T23:59:59.000Z
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.
Dual Axis Radiographic Hydrodynamic Test Facility
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Dual Axis Radiographic Hydrodynamic Test Facility | National Nuclear
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DARHT: Dual-Axis Radiographic Hydrodynamic Test Facility
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DARHT: Dual-Axis Radiographic Hydrodynamic Test Facility
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
of LANL's primary mission: to ensure the safety, security, and effectiveness of nuclear weapons in our nation's stockpile. Los Alamos scientists built DARHT, the world's most...
Hall, G. N., E-mail: hall98@llnl.gov; Izumi, N.; Tommasini, R.; Carpenter, A. C.; Palmer, N. E.; Zacharias, R.; Felker, B.; Holder, J. P.; Allen, F. V.; Bell, P. M.; Bradley, D.; Montesanti, R.; Landen, O. L. [Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, California 94550 (United States)
2014-11-15T23:59:59.000Z
Compton radiography is an important diagnostic for Inertial Confinement Fusion (ICF), as it provides a means to measure the density and asymmetries of the DT fuel in an ICF capsule near the time of peak compression. The AXIS instrument (ARC (Advanced Radiography Capability) X-ray Imaging System) is a gated detector in development for the National Ignition Facility (NIF), and will initially be capable of recording two Compton radiographs during a single NIF shot. The principal reason for the development of AXIS is the requirement for significantly improved detection quantum efficiency (DQE) at high x-ray energies. AXIS will be the detector for Compton radiography driven by the ARC laser, which will be used to produce Bremsstrahlung X-ray backlighter sources over the range of 50 keV–200 keV for this purpose. It is expected that AXIS will be capable of recording these high-energy x-rays with a DQE several times greater than other X-ray cameras at NIF, as well as providing a much larger field of view of the imploded capsule. AXIS will therefore provide an image with larger signal-to-noise that will allow the density and distribution of the compressed DT fuel to be measured with significantly greater accuracy as ICF experiments are tuned for ignition.
Hydrodynamic and Structural Performance of the Transverse Horizontal Axis Water Turbine
Gorban, Alexander N.
Hydrodynamic and Structural Performance of the Transverse Horizontal Axis Water Turbine Prof. Guy across the flow THAWT Concept Transverse Horizontal Axis Water Turbine · Length limited only by stiffness;Options for tidal stream power (1) · Axial flow turbines ("underwater windmills") "Unducted" » MCT (most
DARHT Axis-I Diode Simulations II: Geometrical Scaling
Ekdahl, Carl A. Jr. [Los Alamos National Laboratory
2012-06-14T23:59:59.000Z
Flash radiography of large hydrodynamic experiments driven by high explosives is a venerable diagnostic technique in use at many laboratories. Many of the largest hydrodynamic experiments study mockups of nuclear weapons, and are often called hydrotests for short. The dual-axis radiography for hydrodynamic testing (DARHT) facility uses two electron linear-induction accelerators (LIA) to produce the radiographic source spots for perpendicular views of a hydrotest. The first of these LIAs produces a single pulse, with a fixed {approx}60-ns pulsewidth. The second axis LIA produces as many as four pulses within 1.6-{micro}s, with variable pulsewidths and separation. There are a wide variety of hydrotest geometries, each with a unique radiographic requirement, so there is a need to adjust the radiographic dose for the best images. This can be accomplished on the second axis by simply adjusting the pulsewidths, but is more problematic on the first axis. Changing the beam energy or introducing radiation attenuation also changes the spectrum, which is undesirable. Moreover, using radiation attenuation introduces significant blur, increasing the effective spot size. The dose can also be adjusted by changing the beam kinetic energy. This is a very sensitive method, because the dose scales as the {approx}2.8 power of the energy, but it would require retuning the accelerator. This leaves manipulating the beam current as the best means for adjusting the dose, and one way to do this is to change the size of the cathode. This method has been proposed, and is being tested. This article describes simulations undertaken to develop scaling laws for use as design tools in changing the Axis-1 beam current by changing the cathode size.
Annual Report: Hydrodynamics and Radiative Hydrodynamics with Astrophysical Applications
R. Paul Drake
2005-12-01T23:59:59.000Z
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.
Tuning the DARHT Axis-II linear induction accelerator focusing
Ekdahl, Carl A. [Los Alamos National Laboratory
2012-04-24T23:59:59.000Z
Flash radiography of large hydrodynamic experiments driven by high explosives is a well-known diagnostic technique in use at many laboratories, and the Dual-Axis Radiography for Hydrodynamic Testing (DARHT) facility at Los Alamos produces flash radiographs of large hydrodynamic experiments. Two linear induction accelerators (LIAs) make the bremsstrahlung radiographic source spots for orthogonal views of each test. The 2-kA, 20-MeV Axis-I LIA creates a single 60-ns radiography pulse. The 1.7-kA, 16.5-MeV Axis-II LIA creates up to four radiography pulses by kicking them out of a longer pulse that has a 1.6-{mu}s flattop. The Axis-II injector, LIA, kicker, and downstream transport (DST) to the bremsstrahlung converter are described. Adjusting the magnetic focusing and steering elements to optimize the electron-beam transport through an LIA is often called 'tuning.' As in all high-current LIAs, the focusing field is designed to be as close to that of the ideal continuous solenoid as physically possible. In ideal continuous solenoidal transport a smoothly varying beam size can easily be found for which radial forces balance, and the beam is said to be 'matched' to the focusing field. A 'mismatched' beam exhibits unwanted oscillations in size, which are a source of free energy that contributes to emittance growth. This is undesirable, because in the absence of beam-target effects, the radiographic spot size is proportional to the emittance. Tuning the Axis-II LIA is done in two steps. First, the solenoidal focusing elements are set to values designed to provide a matched beam with little or no envelope oscillations, and little or no beam-breakup (BBU) instability growth. Then, steering elements are adjusted to minimize the motion of the centroid of a well-centered beam at the LIA exit. This article only describes the design of the tune for the focusing solenoids. The DARHT Axis-II LIA was required to be re-tuned after installing an accelerator cell to replace a failed solenoid in March of 2012. We took advantage of this opportunity to improve the design of the focusing tune with better models of the remaining partially failed solenoids, better estimates of beam initial conditions, and better values for pulsed-power voltages. As with all previous tunes for Axis-II, this one incorporates measures to mitigate beam-breakup (BBU) instability, image displacement instability (IDI), corkscrew (sweep), and emittance growth. Section II covers the general approach to of design of focusing solenoid tunes for the DARHT Axis-2 LIA. Section III explains the specific requirements and simulations needed to design the tune for the injector, which includes the thermionic electron source, diode, and six induction cells. Section IV explains the requirements and simulations for tuning the main accelerator, which consists of 68 induction cells. Finally, Section V explores sensitivity of the tune to deviations of parameters from nominal, random variations, and uncertainties in values. Four appendices list solenoid settings for this new tune, discuss comparisons of different simulation codes, show halo formation in mismatched beams, and present a brief discussion of the beam envelope equation, which is the heart of the method used to design LIA solenoid tunes.
Annual Report 2006 for Hydrodynamics and Radiation Hydrodynamics with Astrophysical Applications
R. Paul Drake
2007-04-05T23:59:59.000Z
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.
Three-Dimensional Hydrodynamic Model for Prediction of Falling Cylinder Through Water Column
Chu, Peter C.
1 1 Three-Dimensional Hydrodynamic Model for Prediction of Falling Cylinder Through Water Column-coordinate), cylinder's main-axis following coordinate (M-coordinate), and hydrodynamic force following coordinate (F-coordinate system. The hydrodynamic forces (such as the drag and lift forces) and their moments are easily computed
Hydrodynamic analysis of a vertical axis tidal current turbine
Gretton, Gareth I.
2009-01-01T23:59:59.000Z
Tidal currents can be used as a predictable source of sustainable energy, and have the potential to make a useful contribution to the energy needs of the UK and other countries with such a resource. One of the technologies ...
Dynamics of a horizontal cylinder oscillating as a wave energy converter about an off-centred axis.
Lucas, Jorge
2011-11-22T23:59:59.000Z
The hydrodynamic properties of a horizontal cylinder which is free to pitch about an off-centred axis are studied and used to derive the equations of motion of a wave energy converter which extracts energy from incoming ...
Krivcov, Vladimir (Miass, RU); Krivospitski, Vladimir (Miass, RU); Maksimov, Vasili (Miass, RU); Halstead, Richard (Rohnert Park, CA); Grahov, Jurij (Miass, RU)
2011-03-08T23:59:59.000Z
A vertical axis wind turbine is described. The wind turbine can include a top ring, a middle ring and a lower ring, wherein a plurality of vertical airfoils are disposed between the rings. For example, three vertical airfoils can be attached between the upper ring and the middle ring. In addition, three more vertical airfoils can be attached between the lower ring and the middle ring. When wind contacts the vertically arranged airfoils the rings begin to spin. By connecting the rings to a center pole which spins an alternator, electricity can be generated from wind.
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 ...
P. M. Stevenson
2005-07-30T23:59:59.000Z
Hydrodynamics is the appropriate "effective theory" for describing any fluid medium at sufficiently long length scales. This paper treats the vacuum as such a medium and derives the corresponding hydrodynamic equations. Unlike a normal medium the vacuum has no linear sound-wave regime; disturbances always "propagate" nonlinearly. For an "empty vacuum" the hydrodynamic equations are familiar ones (shallow water-wave equations) and they describe an experimentally observed phenomenon -- the spreading of a clump of zero-temperature atoms into empty space. The "Higgs vacuum" case is much stranger; pressure and energy density, and hence time and space, exchange roles. The speed of sound is formally infinite, rather than zero as in the empty vacuum. Higher-derivative corrections to the vacuum hydrodynamic equations are also considered. In the empty-vacuum case the corrections are of quantum origin and the post-hydrodynamic description corresponds to the Gross-Pitaevskii equation. I conjecture the form of the post-hydrodynamic corrections in the Higgs case. In the 1+1-dimensional case the equations possess remarkable `soliton' solutions and appear to constitute a new exactly integrable system.
Digital radiographic systems detect boiler tube cracks
Walker, S. [EPRI, Charlotte, NC (United States)
2008-06-15T23:59:59.000Z
Boiler water wall leaks have been a major cause of steam plant forced outages. But conventional nondestructive evaluation techniques have a poor track record of detecting corrosion fatigue cracking on the inside surface of the cold side of waterwall tubing. EPRI is performing field trials of a prototype direct-digital radiographic system that promises to be a game changer. 8 figs.
SC Brochure_Final_10dec12.indd
National Nuclear Security Administration (NNSA)
at the Dual Axis Radiographic Hydrodynamic Test Facility houses the equipment used to control, calibrate, and monitor the ultra high- power x-ray imaging of materials that...
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)
2005-07-01T23:59:59.000Z
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.
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)
2001-01-01T23:59:59.000Z
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.
Food habits of axis deer (Axis axis) on the Coastal Plain, Calhoun County, Texas
Smith, John Clarence
1971-01-01T23:59:59.000Z
Fluctuations in annual rainfall occur on the study area. Data for 1958 to 1970 were from U. S. Weather Bureau records for Port O' Connor, Texas. 30 Climograph comparing monthly temperature and precipitation at New Delhi, India and Port O' Connor, Texas... bite technique was used to aid in determining the food preference of axis deer. During 156 hours a tame axis doe took 324, 000 bites. Thirty-eight axis deer and 11 white-tailed deer were collected for rumen analysis during the study. Acorns were...
Vertical axis wind turbine airfoil
Krivcov, Vladimir; Krivospitski, Vladimir; Maksimov, Vasili; Halstead, Richard; Grahov, Jurij Vasiljevich
2012-12-18T23:59:59.000Z
A vertical axis wind turbine airfoil is described. The wind turbine airfoil can include a leading edge, a trailing edge, an upper curved surface, a lower curved surface, and a centerline running between the upper surface and the lower surface and from the leading edge to the trailing edge. The airfoil can be configured so that the distance between the centerline and the upper surface is the same as the distance between the centerline and the lower surface at all points along the length of the airfoil. A plurality of such airfoils can be included in a vertical axis wind turbine. These airfoils can be vertically disposed and can rotate about a vertical axis.
Li, Ye; Karri, Naveen K.; Wang, Qi
2014-04-30T23:59:59.000Z
Tidal power as a large-scale renewable source of energy has been receiving significant attention recently because of its advantages over the wind and other renewal energy sources. The technology used to harvest energy from tidal current is called a tidal current turbine. Though some of the principles of wind turbine design are applicable to tidal current turbines, the design of latter ones need additional considerations like cavitation damage, corrosion etc. for the long-term reliability of such turbines. Depending up on the orientation of axis, tidal current turbines can be classified as vertical axis turbines or horizontal axis turbines. Existing studies on the vertical axis tidal current turbine focus more on the hydrodynamic aspects of the turbine rather than the structural aspects. This paper summarizes our recent efforts to study the integrated hydrodynamic and structural aspects of the vertical axis tidal current turbines. After reviewing existing methods in modeling tidal current turbines, we developed a hybrid approach that combines discrete vortex method -finite element method that can simulate the integrated hydrodynamic and structural response of a vertical axis turbine. This hybrid method was initially employed to analyze a typical three-blade vertical axis turbine. The power coefficient was used to evaluate the hydrodynamic performance, and critical deflection was considered to evaluate the structural reliability. A sensitivity analysis was also conducted with various turbine height-to-radius ratios. The results indicate that both the power output and failure probability increase with the turbine height, suggesting a necessity for optimal design. An attempt to optimize a 3-blade vertical axis turbine design with hybrid method yielded a ratio of turbine height to radius (H/R) about 3.0 for reliable maximum power output.
Vaughn, Mark R. (Albuquerque, NM); Robinett, III, Rush D. (Tijeras, NM); Phelan, John R. (Albuquerque, NM); Van Zuiden, Don M. (Albuquerque, NM)
1997-01-21T23:59:59.000Z
A new class of coplanar two-axis angular effectors. These effectors combine a two-axis rotational joint analogous to a Cardan joint with linear actuators in a manner to produce a wider range of rotational motion about both axes defined by the joint. This new class of effectors also allows design of robotic manipulators having very high strength and efficiency. These effectors are particularly suited for remote operation in unknown surroundings, because of their extraordinary versatility. An immediate application is to the problems which arise in nuclear waste remediation.
Hydrodynamic interactions in colloidal crystals
Weeber, Rudolf
2011-01-01T23:59:59.000Z
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.
Three axis velocity probe system
Fasching, George E. (Morgantown, WV); Smith, Jr., Nelson S. (Morgantown, WV); Utt, Carroll E. (Morgantown, WV)
1992-01-01T23:59:59.000Z
A three-axis velocity probe system for determining three-axis positional velocities of small particles in fluidized bed systems and similar applications. This system has a sensor head containing four closely-spaced sensing electrodes of small wires that have flat ends to establish a two axis plane, e.g. a X-Y plane. Two of the sensing electrodes are positioned along one of the axes and the other two are along the second axis. These four sensing electrodes are surrounded by a guard electrode, and the outer surface is a ground electrode and support member for the sensing head. The electrodes are excited by, for example, sinusoidal voltage having a peak-to-peak voltage of up to 500 volts at a frequency of 2 MHz. Capacitive currents flowing between the four sensing electrodes and the ground electrode are influenced by the presence and position of a particle passing the sensing head. Any changes in these currents due to the particle are amplified and synchronously detected to produce positional signal values that are converted to digital form. Using these digital forms and two values of time permit generation of values of the three components of the particle vector and thus the total velocity vector.
CORRESPONDENCE Reduced major axis regression
CORRESPONDENCE Reduced major axis regression and the island rule The Ôisland ruleÕ describes). The slope of the least-squares regression of Y on X, b, measures the extent to which large body sizes tend- ferent way, as the regression of Y ) X on X, and here the slope (b¢) is generally negative (b¢ = b ) 1
Radiographic X-Ray Pulse Jitter
Mitton, C. V., Good, D. E., Henderson, D. J., Hogge, K. W.
2011-01-15T23:59:59.000Z
The Dual Beam Radiographic Facility consists of two identical radiographic sources. Major components of the machines are: Marx generator, water-filled pulse-forming line (PFL), water-filled coaxial transmission line, three-cell inductive voltage adder, and rod-pinch diode. The diode pulse has the following electrical specifications: 2.25-MV, 60-kA, 60-ns. Each source has the following x-ray parameters: 1-mm-diameter spot size, 4-rad at 1 m, 50-ns full width half max. The x-ray pulse is measured with PIN diode detectors. The sources were developed to produce high resolution images on single-shot, high-value experiments. For this application it is desirable to maintain a high level of reproducibility in source output. X-ray pulse jitter is a key metric for analysis of reproducibility. We will give measurements of x-ray jitter for each machine. It is expected that x-ray pulse jitter is predominantly due to PFL switch jitter, and therefore a correlation of the two will be discussed.
Load responsive hydrodynamic bearing
Kalsi, Manmohan S. (Houston, TX); Somogyi, Dezso (Sugar Land, TX); Dietle, Lannie L. (Stafford, TX)
2002-01-01T23:59:59.000Z
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.
Lifshitz Superfluid Hydrodynamics
Shira Chapman; Carlos Hoyos; Yaron Oz
2014-10-09T23:59:59.000Z
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.
Purely hydrodynamic ordering of rotating disks at a finite Reynolds number
Goto, Yusuke
2015-01-01T23:59:59.000Z
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...
A proposed benchmark for simulation in radiographic testing
Jaenisch, G.-R.; Deresch, A.; Bellon, C. [Federal Institute for Materials Research and Testing Unter den Eichen 87, 12205 Berlin (Germany); Schumm, A.; Guerin, P. [EDF R and D, 1 avenue du Général de Gaulle, 92141 Clamart (France)
2014-02-18T23:59:59.000Z
The purpose of this benchmark study is to compare simulation results predicted by various models of radiographic testing, in particular those that are capable of separately predicting primary and scatter radiation for specimens of arbitrary geometry.
Formation Interuniversitaire de Physique Hydrodynamics
Balbus, Steven
Formation Interuniversitaire de Physique Module : Hydrodynamics S. Balbus 1 #12;TO LEARN.8.3 Piston Driven into Gas Cylinder . . . . . . . . . . . . . 73 4.8.4 Driven Acoustic Modes . . . . . . . . . . . . . . . . 110 6.2.3 Inertial Drag of a Sphere by an Ideal Fluid . . . . . . . 113 6.3 Line Vortices and Flow
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
DATA ASSIMILATION IN HYDRODYNAMIC MODELS
modelling and Kalman filters. The thesis consists of a summary report and a collection of seven researchDATA ASSIMILATION IN HYDRODYNAMIC MODELS OF CONTINENTAL SHELF SEAS Jacob Viborg Tornfeldt Sørensen Informatics and Mathematical Modelling Technical University of Denmark Ph.D. Thesis No. 126 Kgs. Lyngby 2004
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
An implicit numerical algorithm general relativistic hydrodynamics
A. Hujeirat
2008-01-09T23:59:59.000Z
An implicit numerical algorithm general relativistic hydrodynamics This article has been replaced by arXiv:0801.1017
Unusual thoracic radiographic findings in children treated for Hodgkin's disease
Jochelson, M.S.; Tarbell, N.J.; Weinstein, H.J.
1986-06-01T23:59:59.000Z
Mantle irradiation is often part of the treatment for Hodgkin's disease. Localized pneumonitis and fibrosis are well-known sequelae of this treatment. We report nine patients with unusual thoracic radiographic findings following treatment for Hodgkin's disease. All nine had mediastinal widening. Seven of these patients received combined modality therapy in which prednisone was given with their MOPP. In these seven patients, an increase in mediastinal width developed at the same time as the radiographic changes of radiation pneumonitis. Two patients developed bilateral infiltrates extending beyond the field of radiation to the lung periphery. In one of these patients, a spontaneous pneumomediastinum developed. One patient underwent mediastinal biopsy that revealed inflammatory changes similar to those seen in radiation pneumonitis. All patients either responded to steroids or had spontaneous regression of radiographic abnormalities supporting the presumed diagnosis of treatment related changes. Recognition of these unusual sequelae of mantle irradiation will aid in differentiating them from infection or tumor and lead to prompt, appropriate treatment.
Neutrino transport and hydrodynamic stability of rotating proto-neutron stars
V. Urpin
2007-04-24T23:59:59.000Z
We consider stability of differentially rotating non-magnetic proto-neutron stars. When neutrino transport is efficient, the star can be subject to a diffusive instability that can occur even in the convectively stable region. The instability arises on the time-scale comparable to the time-scale of thermal diffusion. Hydrodynamic motions driven by the instability can lead to anisotropy in the neutrino flux since the instability is suppressed near the equator and rotation axis.
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
RELIABLE RADIOGRAPHIC INSPECTION OF FLEXIBLE RISERS FOR THE OIL INDUSTRY
Almeida, Romulo M.; Rebello, Joao Marcos A. [Department of Metallurgical and Materials Engineering COPPE/UFRJ-Federal University of Rio de Janeiro P.O. Box 68505 CEP 21941-972, Rio de Janeiro RJ (Brazil); Vaz, Murilo A. [Department of Ocean Engineering-COPPE/UFRJ (Brazil)
2010-02-22T23:59:59.000Z
Flexible risers are composite tubular structures manufactured by the concentric assemblage of cylindrical polymeric and helically wound metallic layers employed to convey pressurized fluids such as oil, gas and water in the ocean environment. The metallic layers account for the flexible risers' structural strength and are dimensioned according to the static and dynamic loads. They are usually installed in a free hanging catenary configuration and are subjected to the direct action of waves and marine currents and wave induced motions from the oil production platform. The fatigue rupture of wire armours in the end fitting or within the riser segment protected by the bend stiffener is an object of major concern. Integrity models have been developed, however inspection techniques are mandatory to ensure that failure is detected. Gammagraphy has been used as a common inspection technique in all regions of the flexible riser, mainly with the single wall-single view method. On the other side, there is not any qualified radiographic procedure to this kind of structure. Radiographic simulation was adopted and its validation with actual gammagraphies and establishment of radiographic parameters to complex radiation geometries were done. Results show the viability of the radiographic inspection analyzing the armour wires' rupture and the displacement between wires.
Some open questions in hydrodynamics
Mateusz Dyndal; Laurent Schoeffel
2014-12-16T23:59:59.000Z
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.
Jet shapes with the broadening axis
Larkoski, Andrew James
Broadening is a classic jet observable that probes the transverse momentum structure of jets. Traditionally, broadening has been measured with respect to the thrust axis, which is aligned along the (hemisphere) jet momentum ...
Actuator assembly including a single axis of rotation locking member
Quitmeyer, James N.; Benson, Dwayne M.; Geck, Kellan P.
2009-12-08T23:59:59.000Z
An actuator assembly including an actuator housing assembly and a single axis of rotation locking member fixedly attached to a portion of the actuator housing assembly and an external mounting structure. The single axis of rotation locking member restricting rotational movement of the actuator housing assembly about at least one axis. The single axis of rotation locking member is coupled at a first end to the actuator housing assembly about a Y axis and at a 90.degree. angle to an X and Z axis providing rotation of the actuator housing assembly about the Y axis. The single axis of rotation locking member is coupled at a second end to a mounting structure, and more particularly a mounting pin, about an X axis and at a 90.degree. angle to a Y and Z axis providing rotation of the actuator housing assembly about the X axis. The actuator assembly is thereby restricted from rotation about the Z axis.
Sandia Energy - Innovative Offshore Vertical-Axis Wind Turbine...
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
Vertical-Axis Wind Turbine Rotors Home Stationary Power Energy Conversion Efficiency Wind Energy Offshore Wind Innovative Offshore Vertical-Axis Wind Turbine Rotors Innovative...
Sandia National Laboratories: horizontal-axis wind turbine
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
horizontal-axis wind turbine Study Compares Floating-Platform Options for Offshore Vertical-Axis Wind Turbines On December 3, 2014, in Energy, News, News & Events, Partnership,...
Sandia Energy - Innovative Offshore Vertical-Axis Wind Turbine...
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
Innovative Offshore Vertical-Axis Wind Turbine Rotors Home Stationary Power Energy Conversion Efficiency Wind Energy Offshore Wind Innovative Offshore Vertical-Axis Wind Turbine...
Foundation of Hydrodynamics of Strongly Interacting Systems
Wong, Cheuk-Yin [ORNL] [ORNL
2014-01-01T23:59:59.000Z
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.
Disruptive Innovation in Numerical Hydrodynamics
Waltz, Jacob I. [Los Alamos National Laboratory
2012-09-06T23:59:59.000Z
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.
COMBINED MODELING OF ACCELERATION, TRANSPORT, AND HYDRODYNAMIC...
Office of Scientific and Technical Information (OSTI)
Search Title: COMBINED MODELING OF ACCELERATION, TRANSPORT, AND HYDRODYNAMIC RESPONSE IN SOLAR FLARES. I. THE NUMERICAL MODEL Acceleration and transport of high-energy particles...
Hydrodynamic experiment conducted in Nevada | National Nuclear...
National Nuclear Security Administration (NNSA)
that mimic many of the properties of nuclear materials. Hydrodynamics refers to the physics involved when solids, under extreme conditions, begin to mix and flow like liquids....
Collision-dominated nonlinear hydrodynamics in graphene
Briscot, U; Gornyi, I V; Titov, M; Narozhny, B N; Mirlin, A D
2015-01-01T23:59:59.000Z
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.
Effects on the Physical Environment (Hydrodynamics, Sediment...
Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site
Sediment Transport, and Water Quality) Effects on the Physical Environment (Hydrodynamics, Sediment Transport, and Water Quality) Effects on the Physical Environment...
Hydrodynamics on non-commutative space --A step toward hydrodynamics of granular materials--
Mayumi Saitou; Kazuharu Bamba; Akio Sugamoto
2014-09-16T23:59:59.000Z
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.
Enclosed, off-axis solar concentrator
Benitez, Pablo; Grip, Robert E; Minano, Juan C; Narayanan, Authi A; Plesniak, Adam; Schwartz, Joel A
2013-11-26T23:59:59.000Z
A solar concentrator including a housing having receiving wall, a reflecting wall and at least two end walls, the receiving, reflecting and end walls defining a three-dimensional volume having an inlet, wherein a vertical axis of the housing is generally perpendicular to the inlet, a receiver mounted on the receiving wall of the housing, the receiver including at least one photovoltaic cell, wherein a vertical axis of the receiver is disposed at a non-zero angle relative to the vertical axis of the housing, at least one clip disposed on the reflecting wall an optical element received within the three-dimensional volume, the optical element including at least one tab, the tab being engaged by the clip to align the optical element with the receiver, and a window received over the inlet to enclose the housing.
A benchmark concept for simulation in radiographic testing
Ewert, U.; Deresch, A.; Bellon, C.; Jaenisch, G.-R. [Federal Institute for Materials Research and Testing Unter den Eichen 87, 12205 Berlin (Germany)
2014-02-18T23:59:59.000Z
The new standard ISO 17636–2:2013 “NDT of welds: Radiographic testing - Part 2: X- and gamma ray techniques with digital detectors” describes a complex procedure for film replacement by phosphor imaging plates and digital detector arrays. RT modeling software should consider these detector types, X-ray film, and the standard requirements for image quality. Practitioners expect the same visibility of image quality indicators (IQI) in the simulated radiographs as in the experimental exposures. The proposed benchmark test is based on the comparison of experimental radiographs taken at BAM with modeled ones of participants. The experimental setup and the determination of the equivalent penetrameter sensitivity (EPS) as described in the procedure of ASTM E 746 are used for quantitative evaluation of the achievable contrast sensitivity for step hole IQIs as considered in Annex B of ISO 17636–2. System classification data for Computed Radiography (CR) and film systems will be provided by BAM according to ISO 11699–1 for selected film systems and according to ASTM E 2446 for selected CR systems. The classification of films and digital detectors is based on the measurement of the dose response function, the basic spatial resolution (SR{sub b}) of the image, and the measured image noise, which depends on the detector efficiency, the quantum statistics, and the detector fixed pattern noise.
Hydrodynamic forces on piggyback pipelines
Jakobsen, M.L.; Sayer, P. [Univ. of Strathclyde, Glasgow (United Kingdom)
1995-12-31T23:59:59.000Z
An increasing number of new offshore pipelines have been designed as bundles, mainly because of overall cost reductions. One popular way of combining two pipelines with different diameters is the piggyback configuration, with the smaller pipeline strapped on top of the main pipeline. The external hydrodynamic forces on this combination are at present very roughly estimated; pipeline engineers need more data to support their designs. This paper presents experimental results for the in-line hydrodynamic loading on three different piggyback set-ups. The models comprised a 0.4 m main pipeline, and three piggyback pipelines with diameters of 0.038 m, 0.059 m and 0.099 m. Each small pipeline was separately mounted to the main pipeline, with a gap equal to its own diameter. These model sizes lie approximately between half- and full-scale. Experiments were undertaken for K{sub C} between 5 and 42, and R{sub e} in the range 0.0 * 10{sup 4} to 8.5 * 10{sup 5}. The results based on Morison`s equation indicate that a simple addition of the separate forces acting on each cylinder underestimates the actual force by up to 35% at low K{sub C} (< {approximately} 10) and by as much as 100% in the drag-dominated regime (K{sub C} > {approximately} 20).
Isodynamic axisymmetric equilibrium near the magnetic axis
Arsenin, V. V., E-mail: arsenin@nfi.kiae.ru [National Research Centre Kurchatov Institute (Russian Federation)
2013-08-15T23:59:59.000Z
Plasma equilibrium near the magnetic axis of an axisymmetric toroidal magnetic confinement system is described in orthogonal flux coordinates. For the case of a constant current density in the vicinity of the axis and magnetic surfaces with nearly circular cross sections, expressions for the poloidal and toroidal magnetic field components are obtained in these coordinates by using expansion in the reciprocal of the aspect ratio. These expressions allow one to easily derive relationships between quantities in an isodynamic equilibrium, in which the absolute value of the magnetic field is constant along the magnetic surface (Palumbo’s configuration)
Hydrodynamic Modeling and the QGP Shear Viscosity
Huichao Song
2012-07-10T23:59:59.000Z
In this article, we will briefly review the recent progress on hydrodynamic modeling and the extraction of the quark-gluon plasma (QGP) specific shear viscosity with an emphasis on results obtained from the hybrid model VISHNU that couples viscous hydrodynamics for the macroscopic expansion of the QGP to the hadron cascade model for the microscopic evolution of the late hadronic stage.
A low order model for vertical axis wind turbines
Drela, Mark
A new computational model for initial sizing and performance prediction of vertical axis wind turbines
Hydrodynamic enhanced dielectrophoretic particle trapping
Miles, Robin R.
2003-12-09T23:59:59.000Z
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.
Effects on the Physical Environment (Hydrodynamics, and Water...
Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site
on the Physical Environment (Hydrodynamics, and Water Quality Food Web) Effects on the Physical Environment (Hydrodynamics, and Water Quality Food Web) Effects on the Physical...
Purely hydrodynamic ordering of rotating disks at a finite Reynolds number
Yusuke Goto; Hajime Tanaka
2015-02-18T23:59:59.000Z
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.
Outpatient radiographic exposure in the first five years of life
Fosarelli, P.D.; DeAngelis, C.
1987-06-01T23:59:59.000Z
Young children receive a variety of diagnostic radiographs over time. In some cases the exposure to radiation may be unwarranted because the films may yield confusing results, or may also need to be repeated because of poor technical quality. Even when the results are clearly negative, the subsequent treatment may proceed as if the film had been positive because of the child's clinical condition. The cumulative effect of such low-dose radiation on infants and children over time is unknown. The number and types of outpatient radiographs received by a cohort of poor children from a hospital-based continuity clinic during their first 5 years of life were reviewed. Also noted were the reason for obtaining the film, whether it was positive for that reason or another, whether the child had a chronic condition that prompted the use of radiograph, and the child's sex, race, and age when the film was obtained. Of the 218 children, 132 (60.6%) received 349 sets of films in their first 5 years. There was no difference in the number of films by race or sex. Chest and posttrauma bone or joint films accounted for 315 sets of films or 90.3% of the total. Overall, 25.8% of the 267 chest films were positive; this varied by age. Only 15% of the chest films were positive in the first year compared with 29 to 49% in the second through fifth years (p less than 0.001). Cough was the respiratory symptom most reliably associated with a positive chest film, both for the cohort (p less than 0.0001) and for children in the first year of life (p less than 0.01).
Optical and radiographical characterization of silica aerogel for Cherenkov radiator
Makoto Tabata; Ichiro Adachi; Yoshikiyo Hatakeyama; Hideyuki Kawai; Takeshi Morita; Keiko Nishikawa
2012-07-17T23:59:59.000Z
We present optical and X-ray radiographical characterization of silica aerogels with refractive index from 1.05 to 1.07 for a Cherenkov radiator. A novel pin-drying method enables us to produce highly transparent hydrophobic aerogels with high refractive index by shrinking wet-gels. In order to investigate the uniformity in the density (i.e., refractive index) of an individual aerogel monolith, we use the laser Fraunhofer method, an X-ray absorption technique, and Cherenkov imaging by a ring imaging Cherenkov detector in a beam test. We observed an increase in density at the edge of the aerogel tiles, produced by pin-drying.
Optical and radiographical characterization of silica aerogel for Cherenkov radiator
Tabata, Makoto; Hatakeyama, Yoshikiyo; Kawai, Hideyuki; Morita, Takeshi; Nishikawa, Keiko
2012-01-01T23:59:59.000Z
We present optical and X-ray radiographical characterization of silica aerogels with refractive index from 1.05 to 1.07 for a Cherenkov radiator. A novel pin-drying method enables us to produce highly transparent hydrophobic aerogels with high refractive index by shrinking wet-gels. In order to investigate the uniformity in the density (i.e., refractive index) of an individual aerogel monolith, we use the laser Fraunhofer method, an X-ray absorption technique, and Cherenkov imaging by a ring imaging Cherenkov detector in a beam test. We observed an increase in density at the edge of the aerogel tiles, produced by pin-drying.
Hydrodynamic compressibility of high-strength ceramics
Grady, D.E.
1993-08-01T23:59:59.000Z
In this study we have developed the techniques to investigate the hydrodynamic response of high-strength ceramics by mixing these powders with copper powder, preparing compacts, and performing shock compression tests on these mixtures. Hydrodynamics properties of silicon carbide, titanium diboride, and boron carbide to 30 GPa were examined by this method, and hydrodynamic compression data for these ceramics have been determined. We have concluded, however, that the measurement method is sensitive to sample preparation and uncertainties in shock wave measurements. Application of the experimental technique is difficult and further efforts are needed.
Lawson, M. J.; Li, Y.; Sale, D. C.
2011-10-01T23:59:59.000Z
This paper describes the development of a computational fluid dynamics (CFD) methodology to simulate the hydrodynamics of horizontal-axis tidal current turbines. Qualitative measures of the CFD solutions were independent of the grid resolution. Conversely, quantitative comparisons of the results indicated that the use of coarse computational grids results in an under prediction of the hydrodynamic forces on the turbine blade in comparison to the forces predicted using more resolved grids. For the turbine operating conditions considered in this study, the effect of the computational timestep on the CFD solution was found to be minimal, and the results from steady and transient simulations were in good agreement. Additionally, the CFD results were compared to corresponding blade element momentum method calculations and reasonable agreement was shown. Nevertheless, we expect that for other turbine operating conditions, where the flow over the blade is separated, transient simulations will be required.
Shear viscosity, cavitation and hydrodynamics at LHC
Bhatt, Jitesh R; Sreekanth, V
2011-01-01T23:59:59.000Z
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
2011-09-28T23:59:59.000Z
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.
Thermo--hydrodynamics As a Field Theory
Jacek Jezierski; Jerzy Kijowski
2011-12-26T23:59:59.000Z
The field theoretical description of thermo-hydrodynamics is given. It is based on the duality between the physical space--time and the "material space-time" which we construct here. The material space appearing in a natural way in the canonical formulation of the hydrodynamics is completed with a material time playing role of the field potential for temperature. Both Lagrangian and Hamiltonian formulations, the canonical structure, Poisson bracket, N\\"other theorem and conservation laws are discussed.
Hydrodynamic forces on smooth inclined cylinder in oscillatory flow
Kang, H.G. [Dalian Univ. of Technology (China)
1993-12-31T23:59:59.000Z
The hydrodynamic forces on a smooth inclined circular cylinder exposed to oscillating flow were experimentally investigated at Reynolds number (Re) in the range 40,000--200,000 and Keulegan-Capenter number (Kc) in the interval from 5--40. In the test, Re number and Kc number were varied systematically. The inertia force coefficient (C{sub M}) and the drag force coefficient (C{sub D}) in Morison equation were determined form the measured loads and the water particle kinematics. This analysis uses a modified form of Morison equation since it uses the normal velocity and acceleration. Thus, the applicability of the Cross Flow Principle was assumed. This principle, simply stated, is as follows: the force acting in the direction normal to the axis of a cylinder placed at some oblique angle to the direction of flow is expressed in terms of the normal component of flow only, and the axial component is disregarded. Both total in-line force coefficient (C{sub F}) and transverse force (lift) coefficient (C{sub L}) were analyzed in terms of their maximum and root mean square values. All the in-line and lift force coefficient were given as a functions of Re and Kc number. From this research, it can be seen that the Cross-Flow Principle does not always work well. It seems valid for the total in-line force at high Re and large Kc number; the C{sub M} for {alpha} = 45{degree} is larger and the C{sub D} for {alpha} = 45{degree} is smaller than that for {alpha} = 90{degree} and Re {ge} 80,000. The hydrodynamic force coefficients C{sub D} and C{sub M} for the inclined cylinder are only the functions of oblique angle ({alpha}) and Kc number, but not of the Re number.
Vertical axis wind turbine with continuous blade angle adjustment
Weiss, Samuel Bruce
2010-01-01T23:59:59.000Z
The author presents a concept for a vertical axis wind turbine that utilizes each blade's entire rotational cycle for power generation. Each blade has its own vertical axis of rotation and is constrained to rotate at the ...
Sandia National Laboratories: vertical-axis wind turbine research
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
vertical-axis wind turbine research Sandia Vertical-Axis Wind-Turbine Research Presented at Science of Making Torque from Wind Conference On July 8, 2014, in Computational Modeling...
Non-hydrodynamic transport in trapped unitary Fermi gases
Jasmine Brewer; Paul Romatschke
2015-08-05T23:59:59.000Z
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
2015-01-01T23:59:59.000Z
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.
Working safely in gamma radiography. A training manual for industrial radiographers
McGuire, S.A.; Peabody, C.A.
1982-09-01T23:59:59.000Z
This manual is designed for classroom training in working safely in industrial radiography using gamma sources. The purpose is to train radiographers' assistants to work safely as a qualified gamma radiographer. The contents cover the essentials of radiation, radiation protection, emergency procedures, gamma cameras, and biological effects of radiation. (ACR)
Three-axis asymmetric radiation detector system
Martini, Mario Pierangelo (Oak Ridge, TN); Gedcke, Dale A. (Oak Ridge, TN); Raudorf, Thomas W. (Oak Ridge, TN); Sangsingkeow, Pat (Knoxville, TN)
2000-01-01T23:59:59.000Z
A three-axis radiation detection system whose inner and outer electrodes are shaped and positioned so that the shortest path between any point on the inner electrode and the outer electrode is a different length whereby the rise time of a pulse derived from a detected radiation event can uniquely define the azimuthal and radial position of that event, and the outer electrode is divided into a plurality of segments in the longitudinal axial direction for locating the axial location of a radiation detection event occurring in the diode.
Axis Technologies Group Inc | 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 DeliciousPlasmaP a g eWorks - As Prepared forChoiceNEGAustralia: Energy Resources Jump to:AvanzaliaAxis Technologies
Subhas Chandra Bose: darling of the Axis
Getz, Marshall Jay
1993-01-01T23:59:59.000Z
Bose's Memorandum Of Interest To The Nazis Difficult Days In Berlin 110 118 132 CHAPTER The Voice Of Indian Fascism The Fauj End Of A Dream Page 137 150 164 Volume II TABLE OF CONTENTS VI DARLING OF THE AXIS ill 169 Japan: The Tiny... Superpower Indian Nationalists Look To Japan The Story Of Nohan Singh Bose Looks East Bose Becomes Established In Asia VII NOBODY'S DARLING 169 176 182 192 201 214 "Free India" At Last Noney For The Novement On To Delhi Nother India In Turmoil...
Two-axis tracking solar collector mechanism
Johnson, K.C.
1992-12-08T23:59:59.000Z
This invention is a novel solar tracking mechanism incorporating a number of practical features that give it superior environmental resilience and exceptional tracking accuracy. The mechanism comprises a lightweight space-frame assembly supporting an array of point-focus Fresnel lenses in a two-axis tracking structure. The system is enclosed under a glass cover which isolates it from environmental exposure and enhances tracking accuracy by eliminating wind loading. Tracking accuracy is also enhanced by the system's broad-based tracking support. The system's primary intended application would be to focus highly concentrated sunlight into optical fibers for transmission to core building illumination zones, and the system may also have potential for photovoltaic or photothermal solar energy conversion. 16 figs.
Two-axis tracking solar collector mechanism
Johnson, Kenneth C. (201 W. California Ave. #705, Sunnyvale, CA 94086)
1992-01-01T23:59:59.000Z
This invention is a novel solar tracking mechanism incorporating a number of practical features that give it superior environmental resilience and exceptional tracking accuracy. The mechanism comprises a lightweight space-frame assembly supporting an array of point-focus Fresnel lenses in a two-axis tracking structure. The system is enclosed under a glass cover which isolates it from environmental exposure and enhances tracking accuracy by eliminating wind loading. Tracking accuracy is also enhanced by the system's broad-based tracking support. The system's primary intended application would be to focus highly concentrated sunlight into optical fibers for transmission to core building illumination zones, and the system may also have potential for photovoltaic or photothermal solar energy conversion.
Two-axis tracking solar collector mechanism
Johnson, Kenneth C. (201 W. California Ave., #401, Sunnyvale, CA 94086)
1990-01-01T23:59:59.000Z
This invention is a novel solar tracking mechanism incorporating a number of practical features that give it superior environmental resilience and exceptional tracking accuracy. The mechanism comprises a lightweight space-frame assembly supporting an array of point-focus Fresnel lenses in a two-axis tracking structure. The system is enclosed under a glass cover which isolates it from environmental exposure and enhances tracking accuracy by eliminating wind loading. Tracking accuracy is also enhanced by the system's broad-based tracking support. The system's primary intended application would be to focus highly concentrated sunlight into optical fibers for transmission to core building illumination zones, and the system may also have potential for photovoltaic or photothermal solar energy conversion.
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)
2011-12-15T23:59:59.000Z
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.
Ionizing Radiation in Smoothed Particle Hydrodynamics
O. Kessel-Deynet; A. Burkert
2000-02-11T23:59:59.000Z
A new method for the inclusion of ionizing radiation from uniform radiation fields into 3D Smoothed Particle Hydrodynamics (SPHI) simulations is presented. We calculate the optical depth for the Lyman continuum radiation from the source towards the SPHI particles by ray-tracing integration. The time-dependent ionization rate equation is then solved locally for the particles within the ionizing radiation field. Using test calculations, we explore the numerical behaviour of the code with respect to the implementation of the time-dependent ionization rate equation. We also test the coupling of the heating caused by the ionization to the hydrodynamical part of the SPHI code.
Parity Breaking Transport in Lifshitz Hydrodynamics
Carlos Hoyos; Adiel Meyer; Yaron Oz
2015-05-12T23:59:59.000Z
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.
Hydrodynamic analysis of mooring lines based on optical tracking experiments
Yang, Woo Seuk
2009-05-15T23:59:59.000Z
Due to the complexity of body-shape, the investigation of hydrodynamic forces on mooring lines, especially those comprised of chain segments, has not been conducted to a sufficient degree to properly characterize the hydrodynamic damping effect...
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........................................................................... 5 Clam Dredge Construction and Repair
A comparison of on-axis and off-axis heliostat alignment strategies
Jones, S.A.
1996-03-01T23:59:59.000Z
Heliostat installation and alignment costs will be an important element in future solar power tower projects. The predicted annual performances of on- and-off axis strategies are compared for 95 m{sup 2} flat-glass heliostats and an external, molten-salt receiver. Actual approaches to heliostat alignment that have been used in the past are briefly discussed, and relative strengths and limitations are noted. The optimal approach can vary with the application.
General Relativity as Geometro-Hydrodynamics
B. L. Hu
1996-07-29T23:59:59.000Z
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.
2011-01-01T23:59:59.000Z
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...
Adiabatic hydrodynamics: The eightfold way to dissipation
Felix M. Haehl; R. Loganayagam; Mukund Rangamani
2015-03-17T23:59:59.000Z
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.
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)
2010-08-10T23:59:59.000Z
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.
Simple Waves in Ideal Radiation Hydrodynamics
Bryan M. Johnson
2008-11-24T23:59:59.000Z
In the dynamic diffusion limit of radiation hydrodynamics, advection dominates diffusion; the latter primarily affects small scales and has negligible impact on the large scale flow. The radiation can thus be accurately regarded as an ideal fluid, i.e., radiative diffusion can be neglected along with other forms of dissipation. This viewpoint is applied here to an analysis of simple waves in an ideal radiating fluid. It is shown that much of the hydrodynamic analysis carries over by simply replacing the material sound speed, pressure and index with the values appropriate for a radiating fluid. A complete analysis is performed for a centered rarefaction wave, and expressions are provided for the Riemann invariants and characteristic curves of the one-dimensional system of equations. The analytical solution is checked for consistency against a finite difference numerical integration, and the validity of neglecting the diffusion operator is demonstrated. An interesting physical result is that for a material component with a large number of internal degrees of freedom and an internal energy greater than that of the radiation, the sound speed increases as the fluid is rarefied. These solutions are an excellent test for radiation hydrodynamic codes operating in the dynamic diffusion regime. The general approach may be useful in the development of Godunov numerical schemes for radiation hydrodynamics.
Samson, Adeline
, INSERM U738, Groupe Hospitalier Bichat-Claude Bernard, 46 rue Henri Huchard, 75018 Paris, France. Tel for the management of RA in controlled trials (4, 5) and the radiographic outcome is often used as a primary endpoint
Precision 2 g Dual Axis, PWM Output Accelerometer
Lynch, Jerome P.
g shock survival APPLICATIONS Automotive tilt alarms Vehicle dynamic control (VDC Platform stabilization/leveling Alarms and motion detectors High accuracy, 2-axis tilt sensing GENERAL
Hydrodynamic Tesla Wheel Flume for Model and Prototype Testing
Wood, Stephen L.
Hydrodynamic 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, hydrodynamic, laminar, fluid, flow, model, prototype testing, Tesla wheel. I. INTRODUCTION The southeast region
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
Yaw dynamics of horizontal axis wind turbines
Hansen, A.C. (Utah Univ., Salt Lake City, UT (United States))
1992-05-01T23:59:59.000Z
Designers of a horizontal axis wind turbine yaw mechanism are faced with a difficult decision. They know that if they elect to use a yaw- controlled rotor then the system will suffer increased initial cost and increased inherent maintenance and reliability problems. On the other hand, if they elect to allow the rotor to freely yaw they known they will have to account for unknown and random, though bounded, yaw rates. They will have a higher-risk design to trade-off against the potential for cost savings and reliability improvement. The risk of a yaw-free system could be minimized if methods were available for analyzing and understanding yaw behavior. The complexity of yaw behavior has, until recently, discouraged engineers from developing a complete yaw analysis method. The objectives of this work are to (1) provide a fundamental understanding of free-yaw mechanics and the design concepts most effective at eliminating yaw problems, and (2) provide tested design tools and guidelines for use by free-yaw wind systems manufacturers. The emphasis is on developing practical and sufficiently accurate design methods.
Control system for a vertical axis windmill
Brulle, Robert V. (St. Louis County, MO)
1983-10-18T23:59:59.000Z
A vertical axis windmill having a rotating structure is provided with a series of articulated vertical blades whose positions are controlled to maintain a constant RPM for the rotating structure, when wind speed is sufficient. A microprocessor controller is used to process information on wind speed, wind direction and RPM of the rotating structure to develop an electrical signal for establishing blade position. The preferred embodiment of the invention, when connected to a utility grid, is designed to generate 40 kilowatts of power when exposed to a 20 mile per hour wind. The control system for the windmill includes electrical blade actuators that modulate the blades of the rotating structure. Blade modulation controls the blade angle of attack, which in turn controls the RPM of the rotor. In the preferred embodiment, the microprocessor controller provides the operation logic and control functions. A wind speed sensor provides inputs to start or stop the windmill, and a wind direction sensor is used to keep the blade flip region at 90.degree. and 270.degree. to the wind. The control system is designed to maintain constant rotor RPM when wind speed is between 10 and 40 miles per hour.
Three-axis particle impact probe
Fasching, George E. (Morgantown, WV); Smith, Jr., Nelson S. (Morgantown, WV); Utt, Carroll E. (Morgantown, WV)
1992-01-01T23:59:59.000Z
Three-axis particle impact probes detect particle impact vectors along x-, y-, and z-axes by spherical probe head mounted on the outer end of a shaft that is flexibly mounted in silicone rubber at the top of a housing so as to enable motion imparted to the head upon impact to be transmitted to a grounded electrode secured to the shaft within the housing. Excitable electrodes are mounted in the housing in a fixed position, spaced apart from the ground electrode and forming, with the ground electrode, capacitor pairs. Movement of the ground electrode results in changes in capacitance, and these difference in capacitance are used for measurement or derivation of momentum vectors along each of the three axes. In one embodiment, the ground electrode is mounted at the base of the shaft and is secured to a silicone rubber layer at the top of the housing, providing for cantilevered movement. In another embodiment, the shaft is mounted at its mid point in a flexible bushing so that it undergoes pivotal movement around that point.
Event Rates for Off Axis NuMI Experiments
B. Viren
2006-08-25T23:59:59.000Z
Neutrino interaction rates for experiments placed off axis in the NuMI beam are calculated. Primary proton beam energy is 120 GeV and four locations at 810 km from target and 6, 12, 30 and 40 km off axis are considered. This report is part of the Joint FNAL/BNL Future Long Baseline Neutrino Oscillation Experiment Study.
Effective Hydrodynamic Boundary Conditions for Corrugated Surfaces
Mongruel, Anne; Asmolov, Evgeny S; Vinogradova, Olga I
2012-01-01T23:59:59.000Z
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
2015-04-06T23:59:59.000Z
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.
Pursuit and Synchronization in Hydrodynamic Dipoles
Kanso, Eva
2015-01-01T23:59:59.000Z
We study theoretically the behavior of a class of hydrodynamic dipoles. This study is motivated by recent experiments on synthetic and biological swimmers in microfluidic \\textit{Hele-Shaw} type geometries. Under such confinement, a swimmer's hydrodynamic signature is that of a potential source dipole, and the long-range interactions among swimmers are obtained from the superposition of dipole singularities. Here, we recall the equations governing the positions and orientations of interacting asymmetric swimmers in doubly-periodic domains, and focus on the dynamics of swimmer pairs. We obtain two families of `relative equilibria'-type solutions that correspond to pursuit and synchronization of the two swimmers, respectively. Interestingly, the pursuit mode is stable for large tail swimmers whereas the synchronization mode is stable for large head swimmers. These results have profound implications on the collective behavior reported in several recent studies on populations of confined microswimmers.
Hydrodynamic Interactions of Self-Propelled Swimmers
John J. Molina; Yasuya Nakayama; Ryoichi Yamamoto
2013-01-12T23:59:59.000Z
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.
Notes 00. Introduction to Hydrodynamic Lubrication
San Andres, Luis
2010-01-01T23:59:59.000Z
Tribology needs for the 2000?s Dr. Luis San Andres August 2010 Other applications: Sports equipment: compliant, durable, tough, better performance (less friction and less wear) Medicine: Hip-joint replacements, miniature pumps for fluid injection.../removal, heart pumps and implants, 1 MRPM dental hand drills Ultra-hard drilling equipment: no wear and tear, i.e. infinite life Surface engineering, materials. Surface engineering, materials, lubricants. Gas hydrodynamics Nanopowder coatings, Surface engineering...
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
Kleinfeld, David
3-Axis Magnetic Sensor Hybrid HMC2003 The Honeywell HMC2003 is a high sensitivity, three-axis magnetic sensor hybrid assembly used to measure low magnetic field strengths. Honeywell's most sensitive Reference, Traffic Detection, Proximity Detection and Medical Devices Honeywell continues to maintain
Structural Design of a Horizontal-Axis Tidal Current Turbine Composite Blade
Bir, G. S.; Lawson, M. J.; Li, Y.
2011-10-01T23:59:59.000Z
This paper describes the structural design of a tidal composite blade. The structural design is preceded by two steps: hydrodynamic design and determination of extreme loads. The hydrodynamic design provides the chord and twist distributions along the blade length that result in optimal performance of the tidal turbine over its lifetime. The extreme loads, i.e. the extreme flap and edgewise loads that the blade would likely encounter over its lifetime, are associated with extreme tidal flow conditions and are obtained using a computational fluid dynamics (CFD) software. Given the blade external shape and the extreme loads, we use a laminate-theory-based structural design to determine the optimal layout of composite laminas such that the ultimate-strength and buckling-resistance criteria are satisfied at all points in the blade. The structural design approach allows for arbitrary specification of the chord, twist, and airfoil geometry along the blade and an arbitrary number of shear webs. In addition, certain fabrication criteria are imposed, for example, each composite laminate must be an integral multiple of its constituent ply thickness. In the present effort, the structural design uses only static extreme loads; dynamic-loads-based fatigue design will be addressed in the future. Following the blade design, we compute the distributed structural properties, i.e. flap stiffness, edgewise stiffness, torsion stiffness, mass, moments of inertia, elastic-axis offset, and center-of-mass offset along the blade. Such properties are required by hydro-elastic codes to model the tidal current turbine and to perform modal, stability, loads, and response analyses.
Off-axis illumination direct-to-digital holography
Thomas, Clarence E.; Price, Jeffery R.; Voelkl, Edgar; Hanson, Gregory R.
2004-06-08T23:59:59.000Z
Systems and methods are described for off-axis illumination direct-to-digital holography. A method of recording an off-axis illuminated spatially heterodyne hologram including spatially heterodyne fringes for Fourier analysis, includes: reflecting a reference beam from a reference mirror at a non-normal angle; reflecting an object beam from an object at an angle with respect to an optical axis defined by a focusing lens; focusing the reference beam and the object beam at a focal plane of a digital recorder to form the off-axis illuminated spatially heterodyne hologram including spatially heterodyne fringes for Fourier analysis; digitally recording the off-axis illuminated spatially heterodyne hologram including spatially heterodyne fringes for Fourier analysis; Fourier analyzing the recorded off-axis illuminated spatially heterodyne hologram including spatially heterodyne fringes by transforming axes of the recorded off-axis illuminated spatially heterodyne hologram including spatially heterodyne fringes in Fourier space to sit on top of a heterodyne carrier frequency defined as an angle between the reference beam and the object beam; applying a digital filter to cut off signals around an original origin; and then performing an inverse Fourier transform.
Dual-axis hole-drilling ESPI residual stress measurements
Steinzig, Michael [Los Alamos National Laboratory; Schajer, Gary [UNIV OF BRITISH COLUMBIA
2008-01-01T23:59:59.000Z
A novel dual-axis ESPI hole-drilling residual stress measurement method is presented. The method enables the evaluation of all the in-plane normal stress components with similar response to measurement errors, significantly lower than with single-axis measurements. A numerical method is described that takes advantage of, and compactly handles, the additional optical data that are available from the second measurement axis. Experimental tests were conducted on a calibrated specimen to demonstrate the proposed method, and the results supported theoretical expectations.
Kinematic and Dynamic Analyses of the Orthoglide 5-axis
Ur-Rehman, Raza; Chablat, Damien; Wenger, Philippe
2008-01-01T23:59:59.000Z
This paper deals with the kinematic and dynamic analyses of the Orthoglide 5-axis, a five-degree-of-freedom manipulator. It is derived from two manipulators: i) the Orthoglide 3-axis; a three dof translational manipulator and ii) the Agile eye; a parallel spherical wrist. First, the kinematic and dynamic models of the Orthoglide 5-axis are developed. The geometric and inertial parameters of the manipulator are determined by means of a CAD software. Then, the required motors performances are evaluated for some test trajectories. Finally, the motors are selected in the catalogue from the previous results.
Real-time spot size camera for pulsed high-energy radiographic machines
Watson, S.A.
1993-01-01T23:59:59.000Z
The focal spot size of an x-ray source is a critical parameter which degrades resolution in a flash radiograph. For best results, a small round focal spot is required. Therefore, a fast and accurate measurement of the spot size is highly desirable to facilitate machine tuning. This paper describes two systems developed for Los Alamos National Laboratory's Pulsed High-Energy Radiographic Machine Emitting X-rays (PHERMEX) facility. The first uses a CCD camera combined with high-brightness floors, while the second utilizes phosphor storage screens. Other techniques typically record only the line spread function on radiographic film, while systems in this paper measure the more general two-dimensional point-spread function and associated modulation transfer function in real time for shot-to-shot comparison.
Real-time spot size camera for pulsed high-energy radiographic machines
Watson, S.A.
1993-06-01T23:59:59.000Z
The focal spot size of an x-ray source is a critical parameter which degrades resolution in a flash radiograph. For best results, a small round focal spot is required. Therefore, a fast and accurate measurement of the spot size is highly desirable to facilitate machine tuning. This paper describes two systems developed for Los Alamos National Laboratory`s Pulsed High-Energy Radiographic Machine Emitting X-rays (PHERMEX) facility. The first uses a CCD camera combined with high-brightness floors, while the second utilizes phosphor storage screens. Other techniques typically record only the line spread function on radiographic film, while systems in this paper measure the more general two-dimensional point-spread function and associated modulation transfer function in real time for shot-to-shot comparison.
A hybrid type small 5-axis CNC milling machine
Son, Seung-Kil, 1964-
2002-01-01T23:59:59.000Z
5-axis CNC milling machines are important in a number of industries ranging from aerospace to consumer-die-mold machining because they can deliver high machining accuracy with a spindle tilting capacity. Most of these ...
Magnetically suspended reaction sphere with one-axis hysteresis drive
Zhou, Lei., S.M. Massachusetts Institute of Technology
2014-01-01T23:59:59.000Z
This thesis presents the design, modeling, implementation, and control of a magnetically suspended reaction sphere with one-axis hysteresis drive (1D-MSRS). The goal of this project is two fold: (a) exploring the design ...
Determination of Elastic Twist in Horizontal Axis Wind Turbines (HAWTs)
Stoddard, F.; Nelson, V.; Starcher, K.; Andrews, B.
2006-06-01T23:59:59.000Z
This report presents the results of a project at the Alternative Energy Institute (AEI) which measured and calculated the elastic twist of three representative composite horizontal-axis blades: Carter 300, Gougeon ESI 54, and UTRC 8 kW.
Experimental and theoretical study of horizontal-axis wind turbines
Anderson, Michael Broughton
1981-10-20T23:59:59.000Z
An experimental and theoretical study of horizontal-axis wind turbines is undertaken. The theoretical analyses cover the four major areas of aerodynamics, turbulence. aeroelasticity and blade optimisation. EXisting aerodynamic theories based...
A two axis mirror positioning system with quadrature encoder output
Woodruff, Rick Bryan
2007-01-01T23:59:59.000Z
This project was conducted in support of a solar concentrating technology that required the design and construction of a low cost, two axis rotational drive system with a resolution of one degree or better. The scope of ...
General Relativistic Hydrodynamic Simulation of Accretion Flow from a Stellar Tidal Disruption
Shiokawa, Hotaka; Cheng, Roseanne M; Piran, Tsvi; Noble, Scott C
2015-01-01T23:59:59.000Z
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...
Particle-Based Mesoscale Hydrodynamic Techniques
Hiroshi Noguchi; Norio Kikuchi; Gerhard Gompper
2006-10-31T23:59:59.000Z
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 experiment provides key data for Stockpile Stewardship
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
experiments such as Leda involve non-nuclear surrogate materials that mimic many of the properties of nuclear materials. December 22, 2014 Los Alamos hydrodynamic experiment...
Compressible hydrodynamic flow of liquid crystals in 1-D
2009-08-17T23:59:59.000Z
We consider the equation modeling the compressible hydrodynamic flow ... In this paper, we consider the one dimensional initial-boundary value problem for.
Smoothed Particle Hydrodynamics pore-scale simulations of unstable...
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
experiments using the Pair-Wise Force Smoothed Particle Hydrodynamics (PF-SPH) multiphase flow model. First, we derived analytical expressions relating parameters in the...
Assessing Thermo-Hydrodynamic-Chemical Processes at the Dixie...
Transport Modeling Approach Jump to: navigation, search OpenEI Reference LibraryAdd to library Conference Paper: Assessing Thermo-Hydrodynamic-Chemical Processes at the Dixie...
Palacio Mizrahi, J. H. [Physics Department, Technion, Haifa 32000 (Israel)
2014-06-15T23:59:59.000Z
A rigorous derivation of expressions, starting from the governing equations, for the ionization frequency, edge-to-axis ratio of plasma density, plasma density at the axis, and radially averaged plasma density in a cylindrical gas discharge has been obtained. The derived expressions are simple and involve the relevant parameters of the discharge: Cylinder radius, axial current, and neutral gas pressure. The found expressions account for ion inertia, ion temperature, and changes in plasma ion collisionality.
Athens, University of
Robust model-based detection of the lung field boundaries in portable chest radiographs supported of the lung field boundaries in portable chest radiographs supported by selective thresholding D K Iakovidis1-ray misinterpretation rates. This paper presents a novel methodology for the detection of the lung field boundaries
Supernova Hydrodynamics on the Omega Laser
R. Paul Drake
2004-01-16T23:59:59.000Z
(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.
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)
2014-09-20T23:59:59.000Z
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.
Optimization of X-ray Radiographic Imaging Birsen Yazici, Il-Young Son, An Jin
Yazici, Birsen
Visible Human CT data set. To produce a realistic image, the software simulates quantum noise, blurring effects to the patient. All radiographic x-ray examinations require the selection of beam parameters, which affect both by an observer with respect to a quantitative image quality criteria and determine if the images meet
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
Two-axis spin squeezing in two cavities
Caifeng Li; Jingtao Fan; Lixuan Yu; Gang Chen; Tian-Cai Zhang; Suotang Jia
2015-02-02T23:59:59.000Z
Ultracold atoms in an ultrahigh-finesse optical cavity are a powerful platform to produce spin squeezing since photon of cavity mode can induce nonlinear spin-spin interaction and thus generate a one-axis twisting Hamiltonian $H_{\\text{OAT}}=qJ_{x}^{2}$, whose corresponding maximal squeezing factor scales as $N^{-2/3}$, where $N$ is the atomic number. On the contrary, for the other two-axis twisting Hamiltonian $H_{\\text{TAT}}=q(J_{x}^{2}-J_{y}^{2})$, the maximal squeezing factor scales as $N^{-1}$, approaching the Heisenberg limit. In this paper, inspired by recent experiments of cavity-assisted Raman transitions, we propose a scheme, in which an ensemble of ultracold six-level atoms interacts with two quantized cavity fields and two pairs of Raman lasers, to realize a tunable two-axis spin Hamiltonian $%H=q(J_{x}^{2}+\\chi J_{y}^{2})+\\omega_{0}J_{z}$. For proper parameters, the above one- and two- axis twisting Hamiltonians are recovered, and the scaling of $N^{-1}$ of the maximal squeezing factor can occur naturally. On the other hand, in the two-axis twisting Hamiltonian, spin squeezing is usually reduced when increasing the effective atomic resonant frequency $\\omega_{0}$. Surprisingly, we find that by combined with the dimensionless parameter $\\chi(>-1)$, the effective atomic resonant frequency $\\omega_{0}$ can enhance spin squeezing largely. These results are benefit for achieving the required spin squeezing in experiments.
Green's functions and hydrodynamics for isotopic binary diffusion
R. van Zon; E. G. D. Cohen
2005-08-10T23:59:59.000Z
We study classical binary fluid mixtures in which densities vary on very short time (ps) and length (nm) scales, such that hydrodynamics does not apply. In a pure fluid with a localized heat pulse the breakdown of hydrodynamics was overcome using Green's functions which connect the initial densities to those at later times. Numerically it appeared that for long times the results from the Green's functions would approach hydrodynamics. In this paper we extend the Green's functions theory to binary mixtures. For the case of isothermal isobaric mutual diffusion in isotopic binary mixtures and ideal binary mixtures, which is easier to handle than heat conduction yet still non-trivial, we show analytically that in the Green's function approach one recovers hydrodynamic behaviour at long time scales provided the system reaches local equilibrium at long times. This is a first step toward giving the Green's function theory a firmer basis because it can for this case be considered as an extension of hydrodynamics.
Hydrodynamic models for slurry bubble column reactors
Gidaspow, D. [IIT Center, Chicago, IL (United States)
1995-12-31T23:59:59.000Z
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.
Hydrodynamical random walker with chemotactic memory
H. Mohammady; B. Esckandariun; A. Najafi
2014-10-01T23:59:59.000Z
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
1993-10-13T23:59:59.000Z
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.
Code Differentiation for Hydrodynamic Model Optimization
Henninger, R.J.; Maudlin, P.J.
1999-06-27T23:59:59.000Z
Use of a hydrodynamics code for experimental data fitting purposes (an optimization problem) requires information about how a computed result changes when the model parameters change. These so-called sensitivities provide the gradient that determines the search direction for modifying the parameters to find an optimal result. Here, the authors apply code-based automatic differentiation (AD) techniques applied in the forward and adjoint modes to two problems with 12 parameters to obtain these gradients and compare the computational efficiency and accuracy of the various methods. They fit the pressure trace from a one-dimensional flyer-plate experiment and examine the accuracy for a two-dimensional jet-formation problem. For the flyer-plate experiment, the adjoint mode requires similar or less computer time than the forward methods. Additional parameters will not change the adjoint mode run time appreciably, which is a distinct advantage for this method. Obtaining ''accurate'' sensitivities for the j et problem parameters remains problematic.
Deriving Displacement from a 3 axis Accelerometer Mr. Andrew Blake
Winstanley, Graham
Deriving Displacement from a 3 axis Accelerometer Mr. Andrew Blake University of Brighton CMIS, Additive 1. Introduction The Nintendo WiiTM, Sony's Playstation 3TM and Microsoft's Xbox 360TM all feature a 1000 seconds is 1,000,000 times greater than that at 1 second. Any small offset errors
A Simplified Morphing Blade for Horizontal Axis Wind Turbines
Boyer, Edmond
A Simplified Morphing Blade for Horizontal Axis Wind Turbines Weijun WANG , St´ephane CARO, Fouad salinas@hotmail.com The aim of designing wind turbine blades is to improve the power capture ability by adjusting the twist of the blade's root and tip. To evaluate the performance of wind turbine blades
NICMOS OPTICS OffAxis Conicoids Fold Mirrors
Schneider, Glenn
NICMOS OPTICS OffAxis Conicoids Fold Mirrors Cameras 3, 1, 2 Pupil Al ignment Mirror Reimaging Optics (and Witness Samples) Before Installation The integrated NICMOS optical system is comprised of the fifteen NICMOS mirrors are mounted to a graphite epoxy truss, called the ForeOptics Bracket (FOB
Modeling endocrine control of the pituitary-ovarian axis: Androgenic
: aohendri@ncsu.edu 1 #12;Abstract Mathematical models of the hypothalamus-pituitary-ovarian axis in women. Gonadotropin-releasing hormone (GnRH) from the hypothalamus prompts the pituitary to produce follicle and on the ovaries. Pulses of gonadotropin-releasing hormone (GnRH) produced by the hypothalamus on a time scale
Hamilton, Douglas P.
ascension and declination of s with respect to the equator and equinox at epoch J2000.0 are 40.595° and 83.538° respectively (Yoder 1995). Rotating about the vernal equinox by the Earth's obliquity, 23.439° (Yoder 1995), gives s with respect to the ecliptic and equinox as TABLE II: Coordinates of Saturn Spin Axis, j = 18
Energy Gradient Theory of Hydrodynamic Instability
Hua-Shu Dou
2005-01-29T23:59:59.000Z
A new universal theory for flow instability and turbulent transition is proposed in this study. Flow instability and turbulence transition have been challenging subjects for fluid dynamics for a century. The critical condition of turbulent transition from theory and experiments differs largely from each other for Poiseuille flows. In this paper, a new mechanism of flow instability and turbulence transition is presented for parallel shear flows and the energy gradient theory of hydrodynamic instability is proposed. It is stated that the total energy gradient in the transverse direction and that in the streamwise direction of the main flow dominate the disturbance amplification or decay. A new dimensionless parameter K for characterizing flow instability is proposed for wall bounded shear flows, which is expressed as the ratio of the energy gradients in the two directions. It is thought that flow instability should first occur at the position of Kmax which may be the most dangerous position. This speculation is confirmed by Nishioka et al's experimental data. Comparison with experimental data for plane Poiseuille flow and pipe Poiseuille flow indicates that the proposed idea is really valid. It is found that the turbulence transition takes place at a critical value of Kmax of about 385 for both plane Poiseuille flow and pipe Poiseuille flow, below which no turbulence will occur regardless the disturbance. More studies show that the theory is also valid for plane Couette flows and Taylor-Couette flows between concentric rotating cylinders.
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)
2010-09-15T23:59:59.000Z
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
2014-10-28T23:59:59.000Z
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.
An implicit Smooth Particle Hydrodynamic code
Charles E. Knapp
2000-04-01T23:59:59.000Z
An implicit version of the Smooth Particle Hydrodynamic (SPH) code SPHINX has been written and is working. In conjunction with the SPHINX code the new implicit code models fluids and solids under a wide range of conditions. SPH codes are Lagrangian, meshless and use particles to model the fluids and solids. The implicit code makes use of the Krylov iterative techniques for solving large linear-systems and a Newton-Raphson method for non-linear corrections. It uses numerical derivatives to construct the Jacobian matrix. It uses sparse techniques to save on memory storage and to reduce the amount of computation. It is believed that this is the first implicit SPH code to use Newton-Krylov techniques, and is also the first implicit SPH code to model solids. A description of SPH and the techniques used in the implicit code are presented. Then, the results of a number of tests cases are discussed, which include a shock tube problem, a Rayleigh-Taylor problem, a breaking dam problem, and a single jet of gas problem. The results are shown to be in very good agreement with analytic solutions, experimental results, and the explicit SPHINX code. In the case of the single jet of gas case it has been demonstrated that the implicit code can do a problem in much shorter time than the explicit code. The problem was, however, very unphysical, but it does demonstrate the potential of the implicit code. It is a first step toward a useful implicit SPH code.
Vacuum energy: quantum hydrodynamics vs quantum gravity
G. E. Volovik
2005-09-09T23:59:59.000Z
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.
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 ...
A GPU Accelerated Smoothed Particle Hydrodynamics Capability For Houdini
Sanford, Mathew
2012-10-19T23:59:59.000Z
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...
Hydrodynamics and sediment transport in natural and beneficial use marshes
Kushwaha, Vaishali
2006-10-30T23:59:59.000Z
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...
Second-Order Accurate Method for Solving Radiation-Hydrodynamics
Edwards, Jarrod Douglas
2013-11-12T23:59:59.000Z
Second-order discretization for radiation-hydrodynamics is currently an area of great interest. Second-order methods used to solve the respective single-physics problems often differ fundamentally, making it difficult to combine them in a second...
Hydrodynamics and sediment transport in natural and beneficial use marshes
Kushwaha, Vaishali
2006-10-30T23:59:59.000Z
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...
The hydrodynamics of water-walking insects and spiders
Hu, David L., 1979-
2006-01-01T23:59:59.000Z
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 ...
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 ...
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
Fluctuating hydrodynamics approach to equilibrium time correlations for anharmonic chains
Herbert Spohn
2015-05-22T23:59:59.000Z
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.
A new three-dimensional general-relativistic hydrodynamics code
Luca Baiotti; Ian Hawke; Pedro J. Montero; Luciano Rezzolla
2010-04-22T23:59:59.000Z
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.
Sedimentation of pairs of hydrodynamically interacting semiflexible filaments
Isaac Llopis; Ignacio Pagonabarraga; Marco Cosentino Lagomarsino; Christopher P. Lowe
2007-10-08T23:59:59.000Z
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.
Molecular quantum wakes in the hydrodynamic plasma waveguide in air
Wu Jian; Cai Hua; Zeng Heping [State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai 200062 (China); Milchberg, H. M. [Institute for Research in Electronics and Applied Physics, University of Maryland, College Park, Maryland 20742 (United States)
2010-10-15T23:59:59.000Z
We demonstrate a modulated plasma guiding effect from the molecular alignment wakes in the hydrodynamic plasma waveguide. A properly time-delayed laser pulse can be spatially confined by the hydrodynamic expansion induced plasma waveguide of an advancing femtosecond laser pulse. The spatial confinement can be further strengthened or weakened by following the quantum wakes of the impulsively excited rotational wave packets of the molecules in the plasma waveguide.
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
2015-01-18T23:59:59.000Z
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.
X-ray radiographic expansion measurements of isochorically heated thin wire targets
Hochhaus, D. C. [ExtreMe Matter Institute EMMI, GSI, 64291 Darmstadt (Germany) [ExtreMe Matter Institute EMMI, GSI, 64291 Darmstadt (Germany); Goethe-Universität, 60438 Frankfurt am Main (Germany); Frankfurt Institute for Advanced Studies, 60438 Frankfurt am Main (Germany); Aurand, B. [ExtreMe Matter Institute EMMI, GSI, 64291 Darmstadt (Germany) [ExtreMe Matter Institute EMMI, GSI, 64291 Darmstadt (Germany); Johannes Gutenberg-Universität, 55099 Mainz (Germany); Frankfurt Institute for Advanced Studies, 60438 Frankfurt am Main (Germany); Basko, M. [ExtreMe Matter Institute EMMI, GSI, 64291 Darmstadt (Germany) [ExtreMe Matter Institute EMMI, GSI, 64291 Darmstadt (Germany); Alikhanov Institute for Theoretical and Experimental Physics, 117218 Moscow (Russian Federation); Ecker, B. [Johannes Gutenberg-Universität, 55099 Mainz (Germany) [Johannes Gutenberg-Universität, 55099 Mainz (Germany); Helmholtz-Institut Jena, 07743 Jena (Germany); Frankfurt Institute for Advanced Studies, 60438 Frankfurt am Main (Germany); Kühl, T. [GSI Helmholtzzentrum für Schwerionenforschung GmbH, 64291 Darmstadt (Germany) [GSI Helmholtzzentrum für Schwerionenforschung GmbH, 64291 Darmstadt (Germany); Johannes Gutenberg-Universität, 55099 Mainz (Germany); Helmholtz-Institut Jena, 07743 Jena (Germany); ExtreMe Matter Institute EMMI, GSI, 64291 Darmstadt (Germany); Ma, T. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States)] [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States); Rosmej, F. [UPMC, UMR7605, LULI, case 128, 4 Place Jussieu, 75252 Paris Cedex 05 (France) [UPMC, UMR7605, LULI, case 128, 4 Place Jussieu, 75252 Paris Cedex 05 (France); Ecole Polytechnique, LULI, PAPD, Route de Saclay, 91128 Palaiseau Cedex (France); Zielbauer, B. [GSI Helmholtzzentrum für Schwerionenforschung GmbH, 64291 Darmstadt (Germany) [GSI Helmholtzzentrum für Schwerionenforschung GmbH, 64291 Darmstadt (Germany); Helmholtz-Institut Jena, 07743 Jena (Germany); Neumayer, P. [ExtreMe Matter Institute EMMI, GSI, 64291 Darmstadt (Germany) [ExtreMe Matter Institute EMMI, GSI, 64291 Darmstadt (Germany); Frankfurt Institute for Advanced Studies, 60438 Frankfurt am Main (Germany)
2013-06-15T23:59:59.000Z
Solid density matter at temperatures ranging from 150 eV to <5 eV has been created by irradiating thin wire targets with high-energy laser pulses at intensities ?10{sup 18}W/cm{sup 2}. Energy deposition and transport of the laser-produced fast electrons are inferred from spatially resolved K{sub ?}-spectroscopy. Time resolved x-ray radiography is employed to image the target mass density up to solid density and proves isochoric heating. The subsequent hydrodynamic evolution of the target is observed for up to 3 ns and is compared to radiation-hydrodynamic simulations. At distances of several hundred micrometers from the laser interaction region, where temperatures of 5–20 eV and small temperature gradients are found, the hydrodynamic evolution of the wire is a near axially symmetric isentropic expansion, and good agreement between simulations and radiography data confirms heating of the wire over hundreds of micrometers.
On the spin-axis dynamics of a Moonless Earth
Li, Gongjie; Batygin, Konstantin, E-mail: gli@cfa.harvard.edu [Harvard-Smithsonian Center for Astrophysics, The Institute for Theory and Computation, 60 Garden Street, Cambridge, MA 02138 (United States)
2014-07-20T23:59:59.000Z
The variation of a planet's obliquity is influenced by the existence of satellites with a high mass ratio. For instance, Earth's obliquity is stabilized by the Moon and would undergo chaotic variations in the Moon's absence. In turn, such variations can lead to large-scale changes in the atmospheric circulation, rendering spin-axis dynamics a central issue for understanding climate. The relevant quantity for dynamically forced climate change is the rate of chaotic diffusion. Accordingly, here we re-examine the spin-axis evolution of a Moonless Earth within the context of a simplified perturbative framework. We present analytical estimates of the characteristic Lyapunov coefficient as well as the chaotic diffusion rate and demonstrate that even in absence of the Moon, the stochastic change in Earth's obliquity is sufficiently slow to not preclude long-term habitability. Our calculations are consistent with published numerical experiments and illustrate the putative system's underlying dynamical structure in a simple and intuitive manner.
Early hydrodynamic evolution of a stellar collision
Kushnir, Doron; Katz, Boaz [Institute for Advanced Study, Einstein Drive, Princeton, NJ 08540 (United States)
2014-04-20T23:59:59.000Z
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
2014-10-03T23:59:59.000Z
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.
Development of an LED reference light source for calibration of radiographic imaging detectors
M. Weierganz; D. Bar; B. Bromberger; V. Dangendorf; G. Feldman; M. B. Goldberg; M. Lindemann; I. Mor; K. Tittelmeier; D. Vartsky
2010-02-08T23:59:59.000Z
A stable reference light source based on an LED (Light Emission Diode) is presented for stabilizing the conversion gain of the opto-electronic system of a gamma- and fast-neutron radiographic and tomographic imaging device. A constant fraction of the LED light is transported to the image plane of the camera and provides a stable reference exposure. This is used to normalize the images during off-line image processing. We have investigated parameters influencing the stability of LEDs and developed procedures and criteria to prepare and select LEDs suitable for delivering stable light outputs for several 100 h of operation.
MHK Technologies/Vertical Axis Venturi System | 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 DeliciousPlasmaP a gHigh Plains Wind Farm JumpKahului,Coos Bay OPTMHKMultiMHKTREKVertical Axis Venturi System < MHK
Z-Axis Tipper Electromagnetics | 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 onsource History View NewUS National FuelYancey County, North Carolina: Energy ResourcesYokayoYoung County,YuYumaZ-Axis
Space variations in axis height of the jet stream core
Leutwyler, Cooke Hearon
1965-01-01T23:59:59.000Z
height, of 55 mb be- tween Model I (troughs) and Model II (ridges). However, the present models of the jet stream do not adequately describe the way a jet stream axis varies in height at a given time. The average presented by Reiter (1958... the Ridge cases, the standard deviation was smaller upstream from the reference height than it was downstream. Therefore the mean curves are more representative and useful as models upstream than they are downstream. C HAP TER I I I HEIGHT VARIATIONS...
Off-Axis Parabola Inserter - Laboratory for Laser Energetics
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:1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level:5 TablesExports(Journal Article) | SciTech Connect Journal Article: X-rayContract DocumentsofDioxideNotes andresourcesSpeeding Outreach EffortsAxis
Axis-1 diode simulations I: standard 2-inch cathode
Ekdahl, Carl [Los Alamos National Laboratory
2011-01-11T23:59:59.000Z
The standard configuration of the DARHT Axis-I diode features a 5.08-cm diameter velvet emitter mounted in the flat surface of the cathode shroud. The surface of the velvet is slightly recessed {approx}2.5 mm. This configuration produces a 1.75 kA beam when a 3.8-MV pulse is applied to the anode-cathode (AK) gap. This note addresses some of the physics of this diode through the use of finite-element simulations.
Medial-Axis Biased Rapidly-Exploring Random Trees
Greco, Evan
2012-05-09T23:59:59.000Z
, 1998, 1998. [3] S. A. Wilmarth, N. M. Amato, and P. F. Stiller, MAPRM: A probabilistic roadmap planner with sampling on the medial axis of the free space. In Proc. IEEE Int. Conf. Robot. Autom. (ICRA), vol. 2, pp. 1024{1031, 1999. [4] J. J. Ku?ner and S.... M. LaValle, RRT-Connect: An eÆcient approach to single- query path planning. In Proc. IEEE Int. Conf. Robot. Autom. (ICRA), pp. 995{1001, 2000. [5] S. Rodriguez, X. Tang, J. M. Lien, and N. M. Amato, An obstacle-based rapidly- exploring random tree...
Multi-Fidelity Uncertainty Quantification: Application to a Vertical Axis Wind Turbine Under an
Alonso, Juan J.
Multi-Fidelity Uncertainty Quantification: Application to a Vertical Axis Wind Turbine Under, USA Designing better vertical axis wind turbines (VAWTs) requires considering the uncertain wind cost. Low-fidelity tools are used extensively in the modeling of vertical axis wind turbines (VAWTs)3
CFD Simulation of Dynamic Thrust and Radial Forces on a Vertical Axis Wind Turbine Blade
Tullis, Stephen
CFD Simulation of Dynamic Thrust and Radial Forces on a Vertical Axis Wind Turbine Blade K. Mc vibration source of a small scale vertical axis wind turbine. The dynamic loading on the blades detail. 1. INTRODUCTION A prototype of a small scale vertical axis wind turbine is currently being field
Experimental investigation of the performance of a diffuser-augmented vertical axis wind turbine
Victoria, University of
Experimental investigation of the performance of a diffuser- augmented vertical axis wind turbine Experimental investigation of the performance of a diffuser-augmented vertical axis wind turbine by Arash The performance of a vertical axis wind turbine with and without a diffuser was studied using direct force
A Low Order Model for Vertical Axis Wind Turbines Isaac M. Asher
Peraire, Jaime
A Low Order Model for Vertical Axis Wind Turbines Isaac M. Asher , Mark Drela and Jaime Peraire and performance prediction of vertical axis wind turbines is presented. The model uses a 2D hybrid dynamic vortex perpendicular. z perpendicular to the plane (spanwise direction). I. Introduction Darrieus-type vertical axis
Blade Offset and Pitch Effects on a High Solidity Vertical Axis Wind Turbine
Tullis, Stephen
Blade Offset and Pitch Effects on a High Solidity Vertical Axis Wind Turbine Andrzej J. Fiedler ABSTRACT A high solidity, small scale, 2.5m diameter by 3m high Vertical Axis Wind Turbine (VAWT turbines. Keywords: Vertical Axis Wind Turbine, VAWT, airfoil, pitch, blade, mount, offset, high solidity
Flux Distribution of a Single-Axis Tracking Parabolic Trough Array with Photovoltaic Receiver
. With single-axis tracking the incident solar rays are not in general perpendicular to the trough. NonFlux Distribution of a Single-Axis Tracking Parabolic Trough Array with Photovoltaic Receiver G 0200 Australia E-mail: gregory.burgess@anu.edu.au Abstract Single-axis tracking parabolic troughs
Bulk Viscosity Effects in Event-by-Event Relativistic Hydrodynamics
Jacquelyn Noronha-Hostler; Gabriel S. Denicol; Jorge Noronha; Rone P. G. Andrade; Frederique Grassi
2013-05-10T23:59:59.000Z
Bulk viscosity effects on the collective flow harmonics in heavy ion collisions are investigated, on an event by event basis, using a newly developed 2+1 Lagrangian hydrodynamic code named v-USPhydro which implements the Smoothed Particle Hydrodynamics (SPH) algorithm for viscous hydrodynamics. A new formula for the bulk viscous corrections present in the distribution function at freeze-out is derived starting from the Boltzmann equation for multi-hadron species. Bulk viscosity is shown to enhance the collective flow Fourier coefficients from $v_2(p_T)$ to $v_5(p_T)$ when $% p_{T}\\sim 1-3$ GeV even when the bulk viscosity to entropy density ratio, $% \\zeta/s$, is significantly smaller than $1/(4\\pi)$.
Hydrodynamic Correlations slow down Crystallization of Soft Colloids
Roehm, Dominic; Arnold, Axel
2013-01-01T23:59:59.000Z
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...
Non-decaying hydrodynamic interactions along narrow channels
Misiunas, Karolis; Lauga, Eric; Lister, John R; Keyser, Ulrich F
2015-01-01T23:59:59.000Z
Particle-particle interactions are of paramount importance in every multi-body system as they determine the collective behaviour and coupling strength. Many well-known interactions like electro-static, van der Waals or screened Coulomb, decay exponentially or with negative powers of the particle spacing r. Similarly, hydrodynamic interactions between particles undergoing Brownian motion decay as 1/r in bulk, and are assumed to decay quickly in small channels. Such interactions are ubiquitous in biological and technological systems. Here we confine two particles undergoing Brownian motion in narrow, microfluidic channels and study their coupling through hydrodynamic interactions. Our experiments show that, in contrast to expectations from current theoretical understanding, the hydrodynamic particle-particle interactions are long-range and non-decaying in these channels. This new effect is of fundamental importance for the interpretation of experiments where dense mixtures of particles or molecules diffuse thro...
Conformational Manipulation of DNA in Nanochannels Using Hydrodynamics
Qihao He; Hubert Ranchon; Pascal Carrivain; Yannick Viero; Joris Lacroix; Charline Blatché; Emmanuelle Daran; Jean-Marc Victor; Aurélien Bancaud
2014-09-01T23:59:59.000Z
The control over DNA elongation in nanofluidic devices holds great potential for large-scale genomic analysis. So far, the manipulation of DNA in nanochannels has been mostly carried out with electrophoresis and seldom with hydrodynamics, although the physics of soft matter in nanoscale flows has raised considerable interest over the past decade. In this report the migration of DNA is studied in nanochannels of lateral dimension spanning 100 to 500 nm using both actuation principles. We show that the relaxation kinetics are 3-fold slowed down and the extension increases up to 3-fold using hydrodynamics. We propose a model to account for the onset in elongation with the flow, which assumes that DNA response is determined by the shear-driven lift forces mediated by the proximity of the channels' walls. Overall, we suggest that hydrodynamic actuation allows for an improved manipulation of DNA in nanochannels.
Collective excitations of hydrodynamically coupled driven colloidal particles
Harel Nagar; Yael Roichman
2014-08-21T23:59:59.000Z
Two colloidal particles, driven around an optical vortex trap, have been recently shown to pair due to an interplay between hydrodynamic interactions and the curved path they are forced to follow. We demonstrate here, that this pairing interaction can be tuned experimentally, and study its effect on the collective excitations of many particles driven around such an optical trap. We find that even though the system is overdamped, hydrodynamic interactions due to driving give rise to non-decaying excitations with characteristic dispersion relations. The collective excitations of the colloidal ring reflect fluctuations of particle pairs rather than those of single particles.
3-D HYDRODYNAMIC MODELING IN A GEOSPATIAL FRAMEWORK
Bollinger, J; Alfred Garrett, A; Larry Koffman, L; David Hayes, D
2006-08-24T23:59:59.000Z
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.
Anisotropic hydrodynamics for mixture of quark and gluon fluids
Florkowski, Wojciech; Ryblewski, Radoslaw; Tinti, Leonardo
2015-01-01T23:59:59.000Z
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.
Accounting for backflow in hydrodynamic-simulation interfaces
Scott Pratt
2014-01-01T23:59:59.000Z
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
Off-Axis Undulator Radiation for CLIC Drive Beam Diagnostics
Jeff, A; Welsch, CP
2013-01-01T23:59:59.000Z
The Compact LInear Collider (CLIC) will use a novel acceleration scheme in which energy extracted from a very intense beam of relatively low-energy electrons (the Drive Beam) is used to accelerate a lower intensity Main Beam to very high energy. The high intensity of the Drive Beam, with pulses of more than 1015 electrons, poses a challenge for conventional profile measurements such as wire scanners. Thus, new non-invasive profile measurements are being investigated. In this paper we propose the use of relatively inexpensive permanent-magnet undulators to generate off-axis visible Synchrotron Radiation from the CLIC Drive Beam. The field strength and period length of the undulator should be designed such that the on-axis undulator wavelength is in the ultra-violet. A smaller but still useable amount of visible light is then generated in a hollow cone. This light can be reflected out of the beam pipe by a ring-shaped mirror placed downstream and imaged on a camera. In this contribution, results of SRW and ZEMA...
An Optical Streak Diagnostic for Observing Anode-Cathode Plasmas for Radiographic Source Development
Droemer, Darryl W. [National Security Technologies, LLC; Crain, Marlon D.; Lare, Gregory A. [National Security Technologies, LLC; Bennett, Nichelle L. [National Security Technologies, LLC; Johnston, Mark D. [Sandia National Laboratories
2013-06-13T23:59:59.000Z
National Security Technologies, LLC, and Sandia National Laboratories are collaborating in the development of pulsed power–driven flash x-ray radiographic sources that utilize high-intensity electron beam diodes. The RITS 6 (Radiographic Integrated Test Stand) accelerator at Sandia is used to drive a self magnetic pinch diode to produce a Bremsstrahlung x-ray source. The high electric fields and current densities associated with these short A-K gap pinch beam diodes present many challenges in diode development. Plasmas generated at both the anode and cathode affect the diode performance, which is manifested in varying spot (source) sizes, total dose output, and impedance profiles. Understanding the nature of these plasmas including closure rates and densities is important in modeling their behavior and providing insight into their mitigation. In this paper we describe a streak camera–based optical diagnostic that is capable of observing and measuring plasma evolution within the A-K gap. By imaging a region of interest onto the input slit of a streak camera, we are able to produce a time-resolved one-dimensional image of the evolving plasma. Typical data are presented.
Benedict, Joshua King
2011-01-01T23:59:59.000Z
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
Tullis, Stephen
IntroductionIntroduction The use of small scale vertical axis wind turbinesThe use of small scale vertical axis wind turbines (VAWT) is being studied at McMaster University using(VAWT) is being studied at McMaster University using a prototype wind turbine provided bya prototype wind turbine provided
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
Epps, Brenden P
2010-01-01T23:59:59.000Z
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, ...
Self-Similar Radiation-Hydrodynamics Solutions in the Equilibrium Diffusion Limit
Lane, Taylor Kinsey
2013-01-31T23:59:59.000Z
, 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...
Dong, Cheng
Hydrodynamic Shear Rate Regulates Melanoma-Leukocyte Aggregation, Melanoma Adhesion that polymorphonuclear neutrophils (PMNs) may enhance melanoma adhesion to the endothelium (EC) and subsequent microenvironment within the microcirculation. In this study, effects of hydrodynamic flow on regulating melanoma
Simon, Scott I.
Hydrodynamic Shear Rate Regulates Melanoma-Leukocyte Aggregation, Melanoma Adhesion that polymorphonuclear neutrophils (PMNs) may enhance melanoma adhesion to the endothelium (EC) and subsequent microenvironment within the microcirculation. In this study, effects of hydrodynamic flow on regulating melanoma
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
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
Linearly resummed hydrodynamics in a weakly curved spacetime
Yanyan Bu; Michael Lublinsky
2015-02-27T23:59:59.000Z
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.
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
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
Hydrodynamic model for picosecond propagation of laser-created nanoplasmas
Saxena, Vikrant; Ziaja, Beata; Santra, Robin
2015-01-01T23:59:59.000Z
The interaction of a free-electron-laser pulse with a moderate or large size cluster is known to create a quasi-neutral nanoplasma, which then expands on hydrodynamic timescale, i.e., $>1$ ps. To have a better understanding of ion and electron data from experiments derived from laser-irradiated clusters, one needs to simulate cluster dynamics on such long timescales for which the molecular dynamics approach becomes inefficient. We therefore propose a two-step Molecular Dynamics-Hydrodynamic scheme. In the first step we use molecular dynamics code to follow the dynamics of an irradiated cluster until all the photo-excitation and corresponding relaxation processes are finished and a nanoplasma, consisting of ground-state ions and thermalized electrons, is formed. In the second step we perform long-timescale propagation of this nanoplasma with a computationally efficient hydrodynamic approach. In the present paper we examine the feasibility of a hydrodynamic two-fluid approach to follow the expansion of spherica...
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
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
Event-by-event hydrodynamics: A better tool to study the Quark-Gluon plasma
Grassi, Frederique [Instituto de Fisica, Universidade de Sao Paulo (Brazil)
2013-03-25T23:59:59.000Z
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.
Dmytro Oliinychenko; Hannah Petersen
2015-08-18T23:59:59.000Z
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\
Oliinychenko, Dmytro
2015-01-01T23:59:59.000Z
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\
Dual-axis resonance testing of wind turbine blades
Hughes, Scott; Musial, Walter; White, Darris
2014-01-07T23:59:59.000Z
An apparatus (100) for fatigue testing test articles (104) including wind turbine blades. The apparatus (100) includes a test stand (110) that rigidly supports an end (106) of the test article (104). An actuator assembly (120) is attached to the test article (104) and is adapted for substantially concurrently imparting first and second forcing functions in first and second directions on the test article (104), with the first and second directions being perpendicular to a longitudinal axis. A controller (130) transmits first and second sets of displacement signals (160, 164) to the actuator assembly (120) at two resonant frequencies of the test system (104). The displacement signals (160, 164) initiate the actuator assembly (120) to impart the forcing loads to concurrently oscillate the test article (104) in the first and second directions. With turbine blades, the blades (104) are resonant tested concurrently for fatigue in the flapwise and edgewise directions.
Nonlinear characterization of a single-axis acoustic levitator
Andrade, Marco A. B. [Institute of Physics, University of São Paulo, São Paulo (Brazil)] [Institute of Physics, University of São Paulo, São Paulo (Brazil); Ramos, Tiago S.; Okina, Fábio T. A.; Adamowski, Julio C. [Department of Mechatronics and Mechanical Systems Engineering, Escola Politécnica, University of São Paulo, São Paulo (Brazil)] [Department of Mechatronics and Mechanical Systems Engineering, Escola Politécnica, University of São Paulo, São Paulo (Brazil)
2014-04-15T23:59:59.000Z
The nonlinear behavior of a 20.3 kHz single-axis acoustic levitator formed by a Langevin transducer with a concave radiating surface and a concave reflector is experimentally investigated. In this study, a laser Doppler vibrometer is applied to measure the nonlinear sound field in the air gap between the transducer and the reflector. Additionally, an electronic balance is used in the measurement of the acoustic radiation force on the reflector as a function of the distance between the transducer and the reflector. The experimental results show some effects that cannot be described by the linear acoustic theory, such as the jump phenomenon, harmonic generation, and the hysteresis effect. The influence of these nonlinear effects on the acoustic levitation of small particles is discussed.
Mofrad, Mohammad R. K.
, in order to better resolve the drag profiles along the filament. A large part of the hydrodynamic dragAveraged implicit hydrodynamic model of semiflexible filaments Preethi L. Chandran and Mohammad R 2009; published 26 March 2010 We introduce a method to incorporate hydrodynamic interaction in a model
Tests of the hydrodynamic equivalence of direct-drive implosions with different D2 and 3
Tests of the hydrodynamic equivalence of direct-drive implosions with different D2 and 3 He, D2 and 3 He gases are fully ionized, and hydrodynamically equivalent fuels with different ratios the materials are cho- sen to be as nearly hydrodynamically equivalent as possible. D and 3 He have the special
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
Yu, Victoria; Kishan, Amar U.; Cao, Minsong; Low, Daniel; Lee, Percy; Ruan, Dan, E-mail: druan@mednet.ucla.edu [Department of Radiation Oncology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, California 90024 (United States)] [Department of Radiation Oncology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, California 90024 (United States)
2014-03-15T23:59:59.000Z
Purpose: To demonstrate a new method of evaluating dose response of treatment-induced lung radiographic injury post-SBRT (stereotactic body radiotherapy) treatment and the discovery of bimodal dose behavior within clinically identified injury volumes. Methods: Follow-up CT scans at 3, 6, and 12 months were acquired from 24 patients treated with SBRT for stage-1 primary lung cancers or oligometastic lesions. Injury regions in these scans were propagated to the planning CT coordinates by performing deformable registration of the follow-ups to the planning CTs. A bimodal behavior was repeatedly observed from the probability distribution for dose values within the deformed injury regions. Based on a mixture-Gaussian assumption, an Expectation-Maximization (EM) algorithm was used to obtain characteristic parameters for such distribution. Geometric analysis was performed to interpret such parameters and infer the critical dose level that is potentially inductive of post-SBRT lung injury. Results: The Gaussian mixture obtained from the EM algorithm closely approximates the empirical dose histogram within the injury volume with good consistency. The average Kullback-Leibler divergence values between the empirical differential dose volume histogram and the EM-obtained Gaussian mixture distribution were calculated to be 0.069, 0.063, and 0.092 for the 3, 6, and 12 month follow-up groups, respectively. The lower Gaussian component was located at approximately 70% prescription dose (35 Gy) for all three follow-up time points. The higher Gaussian component, contributed by the dose received by planning target volume, was located at around 107% of the prescription dose. Geometrical analysis suggests the mean of the lower Gaussian component, located at 35 Gy, as a possible indicator for a critical dose that induces lung injury after SBRT. Conclusions: An innovative and improved method for analyzing the correspondence between lung radiographic injury and SBRT treatment dose has been demonstrated. Bimodal behavior was observed in the dose distribution of lung injury after SBRT. Novel statistical and geometrical analysis has shown that the systematically quantified low-dose peak at approximately 35 Gy, or 70% prescription dose, is a good indication of a critical dose for injury. The determined critical dose of 35 Gy resembles the critical dose volume limit of 30 Gy for ipsilateral bronchus in RTOG 0618 and results from previous studies. The authors seek to further extend this improved analysis method to a larger cohort to better understand the interpatient variation in radiographic lung injury dose response post-SBRT.
X-ray radiographic technique for measuring density uniformity of silica aerogel
Makoto Tabata; Yoshikiyo Hatakeyama; Ichiro Adachi; Takeshi Morita; Keiko Nishikawa
2012-12-14T23:59:59.000Z
This paper proposes a new X-ray radiographic technique for measuring density uniformity of silica aerogels used as radiator in proximity-focusing ring-imaging Cherenkov detectors. To obtain high performance in a large-area detector, a key characteristic of radiator is the density (i.e. refractive index) uniformity of an individual aerogel monolith. At a refractive index of n = 1.05, our requirement for the refractive index uniformity in the transverse plane direction of an aerogel tile is |\\delta (n - 1)/(n - 1)| aerogels from a trial production and that of Panasonic products (SP-50) as a reference, and to confirm they have sufficient density uniformity within \\pm 1% along the transverse plane direction. The measurement results show that the proposed technique can quantitatively estimate the density uniformity of aerogels.
X-ray radiographic technique for measuring density uniformity of silica aerogel
Tabata, Makoto; Adachi, Ichiro; Morita, Takeshi; Nishikawa, Keiko; 10.1016/j.nima.2012.09.001
2012-01-01T23:59:59.000Z
This paper proposes a new X-ray radiographic technique for measuring density uniformity of silica aerogels used as radiator in proximity-focusing ring-imaging Cherenkov detectors. To obtain high performance in a large-area detector, a key characteristic of radiator is the density (i.e. refractive index) uniformity of an individual aerogel monolith. At a refractive index of n = 1.05, our requirement for the refractive index uniformity in the transverse plane direction of an aerogel tile is |\\delta (n - 1)/(n - 1)| aerogels from a trial production and that of Panasonic products (SP-50) as a reference, and to confirm they have sufficient density uniformity within \\pm 1% along the transverse plane direction. The measurement results show that the proposed technique can quantitatively estimate the density uniformity of aerogels.
Phonon mean free path of graphite along the c-axis
Wei, Zhiyong; Yang, Juekuan; Chen, Weiyu; Bi, Kedong; Chen, Yunfei, E-mail: yunfeichen@seu.edu.cn [Jiangsu Key Laboratory for Design and Manufacture of Micro/Nano Biomedical Instruments and School of Mechanical Engineering, Southeast University, Nanjing 210096 (China); Li, Deyu, E-mail: deyu.li@vanderbilt.edu [Department of Mechanical Engineering, Vanderbilt University, Nashville, Tennessee 37235-1592 (United States)
2014-02-24T23:59:59.000Z
Phonon transport in the c-axis direction of graphite thin films has been studied using non-equilibrium molecular dynamics (MD) simulation. The simulation results show that the c-axis thermal conductivities for films of thickness ranging from 20 to 500 atomic layers are significantly lower than the bulk value. Based on the MD data, a method is developed to construct the c-axis thermal conductivity as an accumulation function of phonon mean free path (MFP), from which we show that phonons with MFPs from 2 to 2000?nm contribute ?80% of the graphite c-axis thermal conductivity at room temperature, and phonons with MFPs larger than 100?nm contribute over 40% to the c-axis thermal conductivity. These findings indicate that the commonly believed value of just a few nanometers from the simple kinetic theory drastically underestimates the c-axis phonon MFP of graphite.
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.,
2002-01-01T23:59:59.000Z
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.
Levin, Judith G.
Using Entrez Utilities Web Service with Apache Axis2 for Java Creating a Web Service Client Entrez Utilities Web Service using Axis2 for Java. Preinstalled Software You should have Apache Axis2.sh shell script file on Linux) in the bin directory of Axis2 installation. You will use it to generate Web
Design and Implementation of a 9-Axis Inertial Measurement Unit Pei-Chun Lin and Chi-Wei Ho
Lin, Pei-Chun
Design and Implementation of a 9-Axis Inertial Measurement Unit Pei-Chun Lin and Chi-Wei Ho Abstract-- We report on a 9-axis inertial measurement unit (IMU) which utilizes 3-axis angular velocity of states. A traditional inertial measurement unit (IMU) is comprised of 3-axis acceleration measurement
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)
2014-09-15T23:59:59.000Z
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.
Galaxies that Shine: radiation-hydrodynamical simulations of disk galaxies
Rosdahl, Joakim; Teyssier, Romain; Agertz, Oscar
2015-01-01T23:59:59.000Z
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 model of Fukushima-Daiichi NPP Industrial site flooding
Vaschenko, V N; Gerasimenko, T V; Vachev, B
2014-01-01T23:59:59.000Z
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...
A new hydrodynamics code for Type Ia Supernovae
Leung, S -C; Lin, L -M
2015-01-01T23:59:59.000Z
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...
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
2012-08-22T23:59:59.000Z
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.
Porous Superhydrophobic Membranes: Hydrodynamic Anomaly in Oscillating Flows
Rajauria, Sukumar; Lawall, J; Yakhot, Victor; Ekinci, Kamil L
2011-01-01T23:59:59.000Z
We have fabricated and characterized a novel superhydrophobic system, a mesh-like porous superhydrophobic membrane with solid area fraction $\\Phi_s$, which can maintain intimate contact with outside air and water reservoirs simultaneously. Oscillatory hydrodynamic measurements on porous superhydrophobic membranes as a function of $\\Phi_s$ reveal surprising effects. The hydrodynamic mass oscillating in-phase with the membranes stays constant for $0.9\\le\\Phi_s\\le1$, but drops precipitously for $\\Phi_s < 0.9$. The viscous friction shows a similar drop after a slow initial decrease proportional to $\\Phi_s$. We attribute these effects to the percolation of a stable Knudsen layer of air at the interface.
Porous Superhydrophobic Membranes: Hydrodynamic Anomaly in Oscillating Flows
Sukumar Rajauria; O. Ozsun; J. Lawall; Victor Yakhot; Kamil L. Ekinci
2011-08-05T23:59:59.000Z
We have fabricated and characterized a novel superhydrophobic system, a mesh-like porous superhydrophobic membrane with solid area fraction $\\Phi_s$, which can maintain intimate contact with outside air and water reservoirs simultaneously. Oscillatory hydrodynamic measurements on porous superhydrophobic membranes as a function of $\\Phi_s$ reveal surprising effects. The hydrodynamic mass oscillating in-phase with the membranes stays constant for $0.9\\le\\Phi_s\\le1$, but drops precipitously for $\\Phi_s < 0.9$. The viscous friction shows a similar drop after a slow initial decrease proportional to $\\Phi_s$. We attribute these effects to the percolation of a stable Knudsen layer of air at the interface.
COSMOS: A Radiation-Chemo-Hydrodynamics Code for Astrophysical Problems
Peter Anninos; P. Chris Fragile; Stephen D. Murray
2003-03-10T23:59:59.000Z
We have developed a new massively-parallel radiation-hydrodynamics code (Cosmos) for Newtonian and relativistic astrophysical problems that also includes radiative cooling, self-gravity, and non-equilibrium, multi-species chemistry. Several numerical methods are implemented for the hydrodynamics, including options for both internal and total energy conserving schemes. Radiation is treated using flux-limited diffusion. The chemistry incorporates 27 reactions, including both collisional and radiative processes for atomic hydrogen and helium gases, and molecular hydrogen chains. In this paper we discuss the equations and present results from test problems carried out to verify the robustness and accuracy of our code in the Newtonian regime. An earlier paper presented tests of the relativistic capabilities of Cosmos.
COSMOS A Radiation-Chemo-Hydrodynamics Code for Astrophysical Problems
Anninos, P; Murray, S D; Anninos, Peter; Murray, Stephen D.
2003-01-01T23:59:59.000Z
We have developed a new massively-parallel radiation-hydrodynamics code (Cosmos) for Newtonian and relativistic astrophysical problems that also includes radiative cooling, self-gravity, and non-equilibrium, multi-species chemistry. Several numerical methods are implemented for the hydrodynamics, including options for both internal and total energy conserving schemes. Radiation is treated using flux-limited diffusion. The chemistry incorporates 27 reactions, including both collisional and radiative processes for atomic hydrogen and helium gases, and molecular hydrogen chains. In this paper we discuss the equations and present results from test problems carried out to verify the robustness and accuracy of our code in the Newtonian regime. An earlier paper presented tests of the relativistic capabilities of Cosmos.
Numerical integration of thermal noise in relativistic hydrodynamics
Clint Young
2013-06-03T23:59:59.000Z
Thermal fluctuations affect the dynamics of systems near critical points, the evolution of the early universe, and two-particle correlations in heavy-ion collisions. For the latter, numerical simulations of nearly-ideal, relativistic fluids are necessary. The correlation functions of noise in relativistic fluids are calculated, stochastic integration of the noise in 3+1-dimensional viscous hydrodynamics is implemented, and the effect of noise on observables in heavy-ion collisions is discussed. Thermal fluctuations will cause significant variance in the event-by-event distributions of integrated v2 while changing average values even when using the same initial conditions, suggesting that including thermal noise will lead to refitting of the hydrodynamical parameters with implications for understanding the physics of hot QCD.
Enhanced Heat Flow in the Hydrodynamic Collisionless Regime
Meppelink, R.; Rooij, R. van; Vogels, J. M.; Straten, P. van der [Atom Optics and Ultrafast Dynamics, Utrecht University, P.O. Box 80000, 3508 TA Utrecht (Netherlands)
2009-08-28T23:59:59.000Z
We study the heat conduction of a cold, thermal cloud in a highly asymmetric trap. The cloud is axially hydrodynamic, but due to the asymmetric trap radially collisionless. By locally heating the cloud we excite a thermal dipole mode and measure its oscillation frequency and damping rate. We find an unexpectedly large heat conduction compared to the homogeneous case. The enhanced heat conduction in this regime is partially caused by atoms with a high angular momentum spiraling in trajectories around the core of the cloud. Since atoms in these trajectories are almost collisionless they strongly contribute to the heat transfer. We observe a second, oscillating hydrodynamic mode, which we identify as a standing wave sound mode.
A hydrodynamic approach to boost invariant free streaming
Esteban Calzetta
2015-08-10T23:59:59.000Z
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.
A hydrodynamic approach to non-equilibrium conformal field theories
Denis Bernard; Benjamin Doyon
2015-07-27T23:59:59.000Z
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
2015-01-01T23:59:59.000Z
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 $t^{1/3}$.
Hydrodynamics of an inelastic gas with implications for sonochemistry
James F. Lutsko
2005-10-09T23:59:59.000Z
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 $\\Delta \\sim 12,000K \\sim 1eV$
Soft Photons from transport and hydrodynamics at FAIR energies
Andreas Grimm; Bjørn Bäuchle
2012-11-11T23:59:59.000Z
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.
Control system for a vertical-axis windmill
Brulle, R.V.
1981-09-03T23:59:59.000Z
A vertical-axis windmill having a rotating structure is provided with a series of articulated vertical blades whose positions are controlled to maintain a constant RPM for the rotating structure, when wind speed is sufficient. A microprocessor controller is used to process information on wind speed, wind direction and RPM of the rotating structure to develop an electrical signal for establishing blade position. The preferred embodiment of the invention, when connected to a utility grid, is designed to generate 40 kilowatts of power when exposed to a 20 mile per hour wind. The control system for the windmill includes electrical blade actuators that modulate the blades of the rotating structure. Blade modulation controls the blade angle of attack, which in turn controls the RPM of the rotor. In the preferred embodiment, the microprocessor controller provides the operation logic and control functions. A wind speed sensor provides inputs to start or stop the windmill, and a wind direction sensor is used to keep the blade flip region at 90 and 270/sup 0/ to the wind. The control system is designed to maintain constant rotor RPM when wind speed is between 10 and 40 miles per hour.
Hydrodynamic analogy of production decline for Devonian shale wells
Pulle, C.V.
1982-01-01T23:59:59.000Z
Several studies on production decline curves have shown that an exponential or hyperbolic curve adequately fits production decline data for Devonian shale wells. Attempts to characterize the production decline based on open flows, rock pressures, and specific shale production mechanisms have also been made. This paper seeks to provide a genesis of the decline curves with the use of a simple hydrodynamic analogy. Some physical factors critical to well productivity are also examined. 4 refs.
Hydrodynamic equations for an electron gas in graphene
Luigi Barletti
2015-09-16T23:59:59.000Z
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
Skew and twist resistant hydrodynamic rotary shaft seal
Dietle, Lannie (Sugar Land, TX); Kalsi, Manmohan Singh (Houston, TX)
1999-01-01T23:59:59.000Z
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.
1999-02-23T23:59:59.000Z
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.
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)
2014-09-10T23:59:59.000Z
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.
Demis, W.D. (Marathon Oil Co., Houston, TX (United States))
1991-03-01T23:59:59.000Z
Hydrocarbons in Mission Canyon dolomite reservoirs in the Elkhorn Ranch field are trapped by downdip flow of formation water to the northeast. Elkhorn Ranch field is located on a north-plunging anticline with only 10 ft (3 m) of crestal closure. The Mission Canyon is a regressive, shallowing upward sequence of subtidal dolomitized mudstones and wackestones grading upward into sebkha-salina evaporites. Mission Canyon oil production is localized on the north and northeast side of the structure. Maps of porosity pinch-outs and permeability barriers defined from core data, superimposed upon the Mission Canyon structure, show that most of the oil cannot be trapped by stratigraphic facies change. Southwest-trending, updip porosity pinch-outs cross the north-plunging structural axis at an angle so low that hydrocarbons would leak out to the southwest under hydrostatic conditions. Downdip hydrodynamic flow to the northeast provides the critical trapping component. Regional maps of apparent formation water resistivity and water salinity show a region of fresher water south and southwest of the field. A regional potentiometric map constructed using Horner-plot extrapolated shut-in pressure data indicates a head gradient of about 20 ft/mi (4 m/km) to the northeast at Elkhorn Ranch field. This gradient corresponds to a calculated water-oil tilt of about 50 ft/mi (20 m/km). Observed tilt of the oil accumulation is actually about 25 ft/mi (5 m/km) to the northeast. This discrepancy might be the result of the field having not yet reached equilibrium with the invading water.
Constructing higher-order hydrodynamics: The third order
Sašo Grozdanov; Nikolaos Kaplis
2015-07-19T23:59:59.000Z
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
2015-01-01T23:59:59.000Z
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...
Hydrodynamically Lubricated Rotary Shaft Having Twist Resistant Geometry
Dietle, Lannie (Houston, TX); Gobeli, Jeffrey D. (Houston, TX)
1993-07-27T23:59:59.000Z
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.
A multiblob approach to colloidal hydrodynamics with inherent lubrication
Adolfo Vázquez-Quesada; Florencio Balboa Usabiaga; Rafael Delgado-Buscalioni
2014-07-23T23:59:59.000Z
This work presents an intermediate resolution model of the hydrodynamics of colloidal particles based on a mixed Eulerian-Lagrangian formulation. The particle is constructed with a small set of overlapping Peskin's Immersed Boundary kernels (blobs) which are held together by springs to build up a particle impenetrable core. Here, we used 12 blobs placed in the vertexes of an icosahedron with an extra one in its center. Although the particle surface is not explicitly resolved, we show that the short-distance hydrodynamic responses (flow profiles, translational and rotational mobilities, lubrication, etc) agree with spherical colloids and provide consistent effective radii. A remarkable property of the present multiblob model is that it naturally presents a "divergent" lubrication force at finite inter-particle distance. This permits to resolve the large viscosity increase at dense colloidal volume fractions. The intermediate resolution model is able to recover highly non-trivial (many-body) hydrodynamics using small particles whose radii are similar to the grid size $h$ (in the range $[1.6-3.2]\\,h$). Considering that the cost of the embedding fluid phase scales like the cube of the particle radius, this result brings about a significant computational speed-up. Our code Fluam works in Graphics Processor Units (GPU's) and uses Fast Fourier Transform for the Poisson solver, which further improves its efficiency.
William H. Lee
2001-08-14T23:59:59.000Z
We present the results of three-dimensional hydrodynamical simulations of the final stages of inspiral in a black hole-neutron star binary, when the separation is comparable to the stellar radius. We use a Newtonian Smooth Particle Hydrodynamics (SPH) code to model the evolution of the system, and take the neutron star to be a polytrope with a soft (adiabatic index G=2 and G=5/3) equation of state and the black hole to be a Newtonian point mass. The only non-Newtonian effect we include is a gravitational radiation back reaction force, computed in the quadrupole approximation for point masses. We use irrotational binaries as initial conditions for our dynamical simulations, which are begun when the system is on the verge of initiating mass transfer and followed for approximately 23 ms. For all the cases studied we find that the star is disrupted on a dynamical time-scale, and forms a massive (the disc mass is approximately 0.2 solar masses) accretion torus around the spinning (Kerr) black hole. The rotation axis is clear of baryons (less than 1.e-5 solar masses within 10 degrees) to an extent that would not preclude the formation of a relativistic fireball capable of powering a cosmological gamma ray burst. Some mass (the specific amount is sensitive to the stiffness of the equation of state) may be dynamically ejected from the system during the coalescence and could undergo r-process nucleosynthesis. We calculate the waveforms, luminosities and energy spectra of the gravitational radiation signal and show how they reflect the global outcome of the coalescence process.
Two-axis MEMS scanner with transfer-printed high-reflectivity, broadband monolithic silicon
Rogers, John A.
Two-axis MEMS scanner with transfer-printed high-reflectivity, broadband monolithic silicon@illinois.edu Abstract: We present a two-axis electrostatic MEMS scanner with high- reflectivity monolithic. The reflective surfaces of the MEMS scanner are transfer-printed PC mirrors with low polarization dependence, low
Model for the prediction of 3D surface topography in 5-axis milling
Paris-Sud XI, Université de
1 Model for the prediction of 3D surface topography in 5-axis milling Sylvain Lavernhe LURPA - ENS surface topography obtained in 5-axis milling in function of the machining conditions. For this purpose to a feed rate prediction model. Thanks to the simulation model of 3D surface topography, the influence
Hydrothermal synthesis, off-axis electron holography and magnetic properties of Fe3O4 nanoparticles
Dunin-Borkowski, Rafal E.
properties investigated using off-axis electron holography and more conventional rock magnetism techniqueHydrothermal synthesis, off-axis electron holography and magnetic properties of Fe3O4 nanoparticles measurements. 1. Introduction The ability of a rock to reliably record the geomagnetic field depends
WIND-TUNNEL STUDY ON AERODYNAMIC PERFORMANCE OF SMALL VERTICAL-AXIS WIND TURBINES
Leu, Tzong-Shyng "Jeremy"
1 WIND-TUNNEL STUDY ON AERODYNAMIC PERFORMANCE OF SMALL VERTICAL-AXIS WIND TURBINES J. J. Miau*1 were carried out to study the aerodynamic performance of three vertical axis wind turbines (VAWTs. On the other hand, the characteristics of unsteady flow around the helical wind turbine were studied with a hot
Near wake properties of horizontal axis marine current L. Myers and A.S. Bahaj
Quartly, Graham
1 Near wake properties of horizontal axis marine current turbines L. Myers and A.S. Bahaj-scale horizontal axis turbine has been have been measured in a large water channel facility. A downstream map with different vertical shear and turbulence distributions. Offshore wind farms are perhaps the most closely
Vibration Analysis of a Vertical Axis Wind Turbine Blade , S.Tullis 2
Tullis, Stephen
Vibration Analysis of a Vertical Axis Wind Turbine Blade K. Mc Laren 1 , S.Tullis 2 and S.Ziada 3 1 vibration source of a small-scale vertical axis wind turbine currently undergoing field-testing. The turbine consists of three 3 metre long vertically aligned blades each fixed to the central shaft by two horizontal
Performance Testing of a Small Vertical-Axis Wind Turbine , S. Tullis2
Tullis, Stephen
Performance Testing of a Small Vertical-Axis Wind Turbine R. Bravo1 , S. Tullis2 , S. Ziada3 vertical-axis wind turbines (VAWT) in urban settings, full-scale wind tunnel testing of a prototype 3.5 k of electric production [1]. Although most performance testing for small-scale wind turbines is conducted
Regulation Of Fshr And SF-1 In The Hypothalamus-Pituitary-Gonadal (HPG) Axis.
George, Jitu Wilson
2013-08-31T23:59:59.000Z
Regulation Of Fshr And SF-1 In The Hypothalamus-Pituitary-Gonadal (HPG) Axis. By Jitu W. George Submitted to the graduate degree program in Molecular and Integrative Physiology and the Graduate Faculty of the University of Kansas in partial... dissertation: Regulation Of Fshr And SF-1 In The Hypothalamus-Pituitary-Gonadal (HPG) Axis. ________________________________ Leslie L...
Multidisciplinary Design Optimization for Glass-Fiber Epoxy-Matrix Composite 5 MW Horizontal-Axis
Grujicic, Mica
.S. energy needs will be met by various onshore and offshore wind-farms (a collection of wind turbines to as the horizontal axis wind turbine (HAWT). A photograph of an offshore wind turbine is pro- vided in Fig. 1. All-Axis Wind-Turbine Blades M. Grujicic, G. Arakere, B. Pandurangan, V. Sellappan, A. Vallejo, and M. Ozen
A flat-cathode thermionic injector for the PHERMEX Radiographic Facility
Kauppila, T.; Builta, L.; Burns, M.; Gregory, W.; Honaberger, D.; Watson, S. (Los Alamos National Lab., NM (United States)); Hughes, T. (Mission Research Corp., Albuquerque, NM (United States))
1993-01-01T23:59:59.000Z
The PHERMEX (Pulsed High-Energy Radiographic Machine Emitting X-rays) standing-wave linear accelerator is a high-current electron beam generator used for flash-radiography. An improved electron gun has been designed employing a flat-thermionic cathode to replace the existing Pierce-geometry gun. The flat cathode yields increased current with the same applied voltage and cathode area as the Pierce gun. The ISIS code simulations indicate a beam current of 1.5 kA at 600 kV. The new geometry also reduces the probability for high voltage breakdown in the A-K gap. A reentrant magnet captures the expanding electron beam and a bucking coil nulls cathode-tinge field. A third coil is used to optimize the extraction field profile and reduce the effect of nonlinear space charge on the beam emittance. Time-resolved measurements of beam current and voltage have been made. In addition, a streak camera was used to measure beam emittance and spatial profile. Comparisons of measurements with simulations are presented.
A flat-cathode thermionic injector for the PHERMEX Radiographic Facility
Kauppila, T.; Builta, L.; Burns, M.; Gregory, W.; Honaberger, D.; Watson, S. [Los Alamos National Lab., NM (United States); Hughes, T. [Mission Research Corp., Albuquerque, NM (United States)
1993-06-01T23:59:59.000Z
The PHERMEX (Pulsed High-Energy Radiographic Machine Emitting X-rays) standing-wave linear accelerator is a high-current electron beam generator used for flash-radiography. An improved electron gun has been designed employing a flat-thermionic cathode to replace the existing Pierce-geometry gun. The flat cathode yields increased current with the same applied voltage and cathode area as the Pierce gun. The ISIS code simulations indicate a beam current of 1.5 kA at 600 kV. The new geometry also reduces the probability for high voltage breakdown in the A-K gap. A reentrant magnet captures the expanding electron beam and a bucking coil nulls cathode-tinge field. A third coil is used to optimize the extraction field profile and reduce the effect of nonlinear space charge on the beam emittance. Time-resolved measurements of beam current and voltage have been made. In addition, a streak camera was used to measure beam emittance and spatial profile. Comparisons of measurements with simulations are presented.
Archuleta, Rita Denise [Los Alamos National Laboratory; Sanchez, Lawrence [Los Alamos National Laboratory
2008-01-01T23:59:59.000Z
The Dual Axis Radiographic Hydrodynamic Test Facility (DARHT) at Los Alamos National Laboratory is the world's most advanced weapons test facility. DARHT contains two linear accelerators for producing flash radiographs of hydrodynamic experiments. High-speed electronics and optical instrumentation are used for triggering the accelerators and collecting accelerator data. Efficient and effective diagnostics provide basic information needed to routinely tune the accelerators for peak radiographic performance, and to successfully monitor the accelerators performance. DARHT's server and network infrastructure is a key element in providing shot related data storage and retrieval for successfully executing radiographic experiments. This paper will outline the elaborate Data Acquisition, Archival, Analysis, and Instrument Control System (DAAAC), as well as the server and network infrastructure for both accelerators.
Xueke Pu; Boling Guo
2015-04-21T23:59:59.000Z
The hydrodynamic equations with quantum effects are studied in this paper. First we establish the global existence of smooth solutions with small initial data and then in the second part, we establish the convergence of the solutions of the quantum hydrodynamic equations to those of the classical hydrodynamic equations. The energy equation is considered in this paper, which added new difficulties to the energy estimates, especially to the selection of the appropriate Sobolev spaces.
RAM: a Relativistic Adaptive Mesh Refinement Hydrodynamics Code
Zhang, Wei-Qun; /KIPAC, Menlo Park; MacFadyen, Andrew I.; /Princeton, Inst. Advanced Study
2005-06-06T23:59:59.000Z
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.
Hydrodynamic and Ecological Assessment of Nearshore Restoration: A Modeling Study
Yang, Zhaoqing; Sobocinski, Kathryn L.; Heatwole, Danelle W.; Khangaonkar, Tarang; Thom, Ronald M.; Fuller, Roger
2010-04-10T23:59:59.000Z
Along the Pacific Northwest coast, much of the estuarine habitat has been diked over the last century for agricultural land use, residential and commercial development, and transportation corridors. As a result, many of the ecological processes and functions have been disrupted. To protect coastal habitats that are vital to aquatic species, many restoration projects are currently underway to restore the estuarine and coastal ecosystems through dike breaches, setbacks, and removals. Information on physical processes and hydrodynamic conditions are critical for the assessment of the success of restoration actions. Restoration of a 160- acre property at the mouth of the Stillaguamish River in Puget Sound has been proposed. The goal is to restore native tidal habitats and estuary-scale ecological processes by removing the dike. In this study, a three-dimensional hydrodynamic model was developed for the Stillaguamish River estuary to simulate estuarine processes. The model was calibrated to observed tide, current, and salinity data for existing conditions and applied to simulate the hydrodynamic responses to two restoration alternatives. Responses were evaluated at the scale of the restoration footprint. Model data was combined with biophysical data to predict habitat responses at the site. Results showed that the proposed dike removal would result in desired tidal flushing and conditions that would support four habitat types on the restoration footprint. At the estuary scale, restoration would substantially increase the proportion of area flushed with freshwater (< 5 ppt) at flood tide. Potential implications of predicted changes in salinity and flow dynamics are discussed relative to the distribution of tidal marsh habitat.
A Moving Frame Algorithm for High Mach Number Hydrodynamics
Hy Trac; Ue-Li Pen
2003-09-24T23:59:59.000Z
We present a new approach to Eulerian computational fluid dynamics that is designed to work at high Mach numbers encountered in astrophysical hydrodynamic simulations. The Eulerian fluid conservation equations are solved in an adaptive frame moving with the fluid where Mach numbers are minimized. The moving frame approach uses a velocity decomposition technique to define local kinetic variables while storing the bulk kinetic components in a smoothed background velocity field that is associated with the grid velocity. Gravitationally induced accelerations are added to the grid, thereby minimizing the spurious heating problem encountered in cold gas flows. Separately tracking local and bulk flow components allows thermodynamic variables to be accurately calculated in both subsonic and supersonic regions. A main feature of the algorithm, that is not possible in previous Eulerian implementations, is the ability to resolve shocks and prevent spurious heating where both the preshock and postshock Mach numbers are high. The hybrid algorithm combines the high resolution shock capturing ability of the second-order accurate Eulerian TVD scheme with a low-diffusion Lagrangian advection scheme. We have implemented a cosmological code where the hydrodynamic evolution of the baryons is captured using the moving frame algorithm while the gravitational evolution of the collisionless dark matter is tracked using a particle-mesh N-body algorithm. The MACH code is highly suited for simulating the evolution of the IGM where accurate thermodynamic evolution is needed for studies of the Lyman alpha forest, the Sunyaev-Zeldovich effect, and the X-ray background. Hydrodynamic and cosmological tests are described and results presented. The current code is fast, memory-friendly, and parallelized for shared-memory machines.
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)
2012-08-15T23:59:59.000Z
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.
Chemo -- Dynamical evolution of disk galaxies, smoothed particles hydrodynamics approach
Peter Berczik
1998-10-20T23:59:59.000Z
A new Chemo -- Dynamical Smoothed Particle Hydrodynamic (CD -- SPH) code is presented. The disk galaxy is described as a multi -- fragmented gas and star system, embedded into the cold dark matter halo. The star formation (SF) process, SNII, SNIa and PN events as well as chemical enrichment of gas have been considered within the framework of standard SPH model. Using this model we try to describe the dynamical and chemical evolution of triaxial disk -- like galaxies. It is found that such approach provides a realistic description of the process of formation, chemical and dynamical evolution of disk galaxies over the cosmological timescale.
Role of Brownian Motion Hydrodynamics on Nanofluid Thermal Conductivity
W Evans, J Fish, P Keblinski
2005-11-14T23:59:59.000Z
We use a simple kinetic theory based analysis of heat flow in fluid suspensions of solid nanoparticles (nanofluids) to demonstrate that the hydrodynamics effects associated with Brownian motion have a minor effect on the thermal conductivity of the nanofluid. Our conjecture is supported by the results of molecular dynamics simulations of heat flow in a model nanofluid with well-dispersed particles. Our findings are consistent with the predictions of the effective medium theory as well as with recent experimental results on well dispersed metal nanoparticle suspensions.
Semiclassical hydrodynamics of a quantum Kane model for semiconductors
Luigi Barletti; Giovanni Borgioli; Giovanni Frosali
2014-02-17T23:59:59.000Z
In this paper we derive a semiclassical hydrodynamic system for electron densities and currents in the two energy bands of a semiconductor. We use the semiclassical Wigner equation with a k.p Hamiltonian and a BGK dissipative term to construct the first two moment equations. The closure of the moment system is obtained using the Maximum Entropy Principle, by minimizing a Gibbs free-energy functional under suitable constraints. We prove that the constraint equations can be uniquely solved, i.e. that the local equilibrium state can be parametrized by the density and velocity field. Some BGK-like models are proposed to mimic the quantum interband migration.
Hydrodynamic effects on coalescence. (Technical Report) | SciTech Connect
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On freeze-out problem in relativistic hydrodynamics
Ivanov, Yu. B., E-mail: Y.Ivanov@gsi.de; Russkikh, V. N. [Gesellschaft fuer Schwerionenforschung mbH (Germany)
2009-07-15T23:59:59.000Z
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.
Skew And Twist Resistant Hydrodynamic Rotary Shaft Seal
Dietle, Lannie (Sugar Land, TX); Kalsi, Manmohan Singh (Houston, TX)
2000-03-14T23:59:59.000Z
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.
Dancing Volvox: Hydrodynamic Bound States of Swimming Algae
Knut Drescher; Kyriacos C. Leptos; Idan Tuval; Takuji Ishikawa; Timothy J. Pedley; Raymond E. Goldstein
2009-01-14T23:59:59.000Z
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.
The Role of Anti-Phase Domains in InSb-Based Structures Grown on On-Axis and Off-Axis Ge Substrates
Debnath, M. C.; Mishima, T. D.; Santos, M. B. [Homer L. Dodge Department of Physics and Astronomy, University of Oklahoma, Norman, OK 73019 (United States); Hossain, K.; Holland, O. W. [Amethyst Research, Inc., 1405 4th Ave NW, Ardmore, OK 73401 (United States)
2011-12-26T23:59:59.000Z
Anti-phase domains form in InSb epilayers and InSb/Al{sub 0.20}In{sub 0.80}Sb single quantum wells when grown upon on-axis (001) Ge substrates by molecular beam epitaxy. Domain formation is partially suppressed through growth on Ge substrates with surfaces that are several degrees off the (001) or (211) axis. By using off-axis Ge substrates, room-temperature electron mobilities increased to {approx}60,000 cm{sup 2}/V-s and {approx}14,000 cm{sup 2}/V-s for a 4.0-{mu}m-thick InSb epilayer and a 25-nm InSb quantum well, respectively.
Annual performance prediction for off-axis aligned Lugo heliostats at Solar Two
Jones, S.A.
1996-02-01T23:59:59.000Z
The DELSOL computer code was used to model the annual Performance for numerous off-axis alignments of the Lugo heliostats located at the Solar Two site in Dagget, California. Recommended canting times are presented for the Lugo heliostats based upon their location in the field. Predicted annual performance of an off-axis alignment was actually higher than for on-axis alignment in some cases, and approximately equal if the recommended times are used. The annual performances of Solar One heliostats located nearby were also calculated, and illustrated the poorer performance expected of the Lugo heliostats.
Refining a relativistic, hydrodynamic solver: Admitting ultra-relativistic flows
J. P. Bernstein; P. A. Hughes
2009-07-23T23:59:59.000Z
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.
Multi-Thread Hydrodynamic Modeling of a Solar Flare
Harry P. Warren
2005-07-13T23:59:59.000Z
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}.
Numerical Simulation of the Hydrodynamical Combustion to Strange Quark Matter
Brian Niebergal; Rachid Ouyed; Prashanth Jaikumar
2010-08-27T23:59:59.000Z
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 1D with neutrino emission from weak equilibrating reactions, and strange quark diffusion across the burning front. We also include entropy change due to 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 approximately 2 times saturation density). In a 2-dimensional setting, such rapid speeds and neutrino cooling may allow for a flame wrinkle instability to develop, possibly leading to detonation.
Hydrodynamic model for electron-hole plasma in graphene
D. Svintsov; V. Vyurkov; S. Yurchenko; T. Otsuji; V. Ryzhii
2012-01-03T23:59:59.000Z
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.
Hydrodynamic and hydromagnetic energy spectra from large eddy simulations
N. E. L. Haugen; A. Brandenburg
2006-06-29T23:59:59.000Z
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
2005-09-15T23:59:59.000Z
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.
Hydrodynamics of rapidly rotating superfluid neutron stars with mutual friction
A. Passamonti; N. Andersson
2010-04-26T23:59:59.000Z
We study time evolutions of superfluid neutron stars, focussing on the nature of the oscillation spectrum, the effect of mutual friction force on the oscillations and the hydrodynamical spin-up phase of pulsar glitches. We linearise the dynamical equations of a Newtonian two-fluid model for rapidly rotating backgrounds. In the axisymmetric equilibrium configurations, the two fluid components corotate and are in beta-equilibrium. We use analytical equations of state that generate stratified and non-stratified stellar models, which enable us to study the coupling between the dynamical degrees of freedom of the system. By means of time evolutions of the linearised dynamical equations, we determine the spectrum of axisymmetric and non-axisymmetric oscillation modes, accounting for the contribution of the gravitational potential perturbations, i.e. without adopting the Cowling approximation. We study the mutual friction damping of the superfluid oscillations and consider the effects of the non-dissipative part of the mutual friction force on the mode frequencies. We also provide technical details and relevant tests for the hydrodynamical model of pulsar glitches discussed by Sidery, Passamonti and Andersson (2010). In particular, we describe the method used to generate the initial data that mimic the pre-glitch state, and derive the equations that are used to extract the gravitational-wave signal.
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)
2014-11-07T23:59:59.000Z
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.
Hydrodynamic Simulation of Supernova Remnants Including Efficient Particle Acceleration
Donald C. Ellison; Anne Decourchelle; Jean Ballet
2003-08-19T23:59:59.000Z
A number of supernova remnants (SNRs) show nonthermal X-rays assumed to be synchrotron emission from shock accelerated TeV electrons. The existence of these TeV electrons strongly suggests that the shocks in SNRs are sources of galactic cosmic rays (CRs). In addition, there is convincing evidence from broad-band studies of individual SNRs and elsewhere that the particle acceleration process in SNRs can be efficient and nonlinear. If SNR shocks are efficient particle accelerators, the production of CRs impacts the thermal properties of the shock heated, X-ray emitting gas and the SNR evolution. We report on a technique that couples nonlinear diffusive shock acceleration, including the backreaction of the accelerated particles on the structure of the forward and reverse shocks, with a hydrodynamic simulation of SNR evolution. Compared to models which ignore CRs, the most important hydrodynamical effects of placing a significant fraction of shock energy into CRs are larger shock compression ratios and lower temperatures in the shocked gas. We compare our results, which use an approximate description of the acceleration process, with a more complete model where the full CR transport equations are solved (i.e., Berezhko et al., 2002), and find excellent agreement for the CR spectrum summed over the SNR lifetime and the evolving shock compression ratio. The importance of the coupling between particle acceleration and SNR dynamics for the interpretation of broad-band continuum and thermal X-ray observations is discussed.
Modelling the Mechanics and Hydrodynamics of Swimming E. coli
Jinglei Hu; Mingcheng Yang; Gerhard Gompper; Roland G. Winkler
2015-08-04T23:59:59.000Z
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.
Bulk Viscosity and Cavitation in Boost-Invariant Hydrodynamic Expansion
Krishna Rajagopal; Nilesh Tripuraneni
2010-02-16T23:59:59.000Z
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
2009-01-01T23:59:59.000Z
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...
Krejcarek, Stephanie C. [Department of Radiation Oncology, Massachusetts General Hospital, Harvard Medical School, Boston, MA (United States); Grant, P. Ellen [Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Boston, MA (United States); Henson, John W. [Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Boston, MA (United States); Pappas Center for Neuro-oncology, Massachusetts General Hospital, Harvard Medical School, Boston, MA (United States); Tarbell, Nancy J. [Department of Radiation Oncology, Massachusetts General Hospital, Harvard Medical School, Boston, MA (United States); Yock, Torunn I. [Department of Radiation Oncology, Massachusetts General Hospital, Harvard Medical School, Boston, MA (United States)]. E-mail: tyock@partners.org
2007-07-01T23:59:59.000Z
Purpose: Fatty replacement of bone marrow resulting from radiation therapy can be seen on T1-weighted magnetic resonance (MR) images. We evaluated the radiographic appearance of the vertebral bodies in children treated with proton craniospinal irradiation (CSI) to illustrate the distal edge effect of proton radiotherapy. Methods and Materials: The study cohort consisted of 13 adolescents aged 12-18 years who received CSI with proton radiotherapy at Massachusetts General Hospital. Ten of these patients had reached maximal or near-maximal growth. Proton beam radiation for these 10 patients was delivered to the thecal sac and exiting nerve roots only, whereas the remaining 3 patients had a target volume that included the thecal sac, exiting nerve roots, and entire vertebral bodies. Median CSI dose was 27 [range, 23.4-36] cobalt gray equivalent (CGE) given in 1.8-CGE fractions. Magnetic resonance images of the spine were obtained after completion of radiotherapy. Results: Magnetic resonance images of patients who received proton radiotherapy to the thecal sac only demonstrate a sharp demarcation of hyperintense T1-weighted signal in the posterior aspects of the vertebral bodies, consistent with radiation-associated fatty marrow replacement. Magnetic resonance images of the patients prescribed proton radiotherapy to the entire vertebral column had corresponding hyperintense T1-weighted signal involving the entire vertebral bodies. Conclusion: The sharp delineation of radiation-associated fatty marrow replacement in the vertebral bodies demonstrates the rapid decrease in energy at the edge of the proton beam. This provides evidence for a sharp fall-off in radiation dose and supports the premise that proton radiotherapy spares normal tissues unnecessary irradiation.
Design and development of a two-axis reluctance based actuator for hexflex nano-positioner
Liles, Howard J
2010-01-01T23:59:59.000Z
An endeavor was conducted to explore the design and development of a two-axis linear reluctance actuator for use as a part of a nano-positioner with the application of serving as a small scale kinematic coupling assembly ...
Content-based fused off-axis object illumination direct-to-digital holography
Price, Jeffery R.
2006-05-02T23:59:59.000Z
Systems and methods are described for content-based fused off-axis illumination direct-to-digital holography. A method includes calculating an illumination angle with respect to an optical axis defined by a focusing lens as a function of data representing a Fourier analyzed spatially heterodyne hologram; reflecting a reference beam from a reference mirror at a non-normal angle; reflecting an object beam from an object the object beam incident upon the object at the illumination angle; focusing the reference beam and the object beam at a focal plane of a digital recorder to from the content-based off-axis illuminated spatially heterodyne hologram including spatially heterodyne fringes for Fourier analysis; and digitally recording the content based off-axis illuminated spatially heterodyne hologram including spatially heterodyne fringes for Fourier analysis.
Verma, Shobhit
2005-11-01T23:59:59.000Z
This dissertation presents two novel 6-axis magnetic-levitation (maglev) stages that are capable of nanoscale positioning. These stages have very simple and compact structure that is advantageous to meet requirements in ...
Spencer, Robert L.
Differential Responses of Hypothalamus-Pituitary- Adrenal Axis Immediate Early Genes Neuroscience, Department of Psychology, University of Colorado, Boulder, Colorado 80309 The hypothalamus by daily fluctuations in activity of CRH neurons within the paraven- tricular nucleus of the hypothalamus
Measurement of c-axis angular orientation in calcite (CaCO3) nanocrystals using
Coppersmith, Susan N.
Measurement of c-axis angular orientation in calcite (CaCO3) nanocrystals using X-ray absorption are demonstrated here on geologic calcite (CaCO3) and used to investigate the prismatic layer of a mollusk shell
Multi-DOF precision positioning methodology using two-axis Hall-effect sensors
Kawato, Yusuke
2006-08-16T23:59:59.000Z
A novel sensing methodology using two-axis Hall-effect sensors is proposed, where the absolute positioning of a device atop any magnet matrix is possible. This methodology has the capability of micrometer-order positioning resolution as well...
Design and Test of a Vertical-Axis Wind Turbine with Pitch Control J. J. Miau1,a
Leu, Tzong-Shyng "Jeremy"
Design and Test of a Vertical-Axis Wind Turbine with Pitch Control J. J. Miau1,a , S. Y. Liang2 , R, USA a jjmiau@mail.ncku.edu.tw Keywords: vertical-axis wind turbine, pitch control, wind of a small vertical-axis wind turbine. Benefits gained can be shown by the experimental and numerical results
The experimental and theoretical investigaton of a horizontal-axis wind turbine
Milburn, Robert Terrance
1977-01-01T23:59:59.000Z
THE EXPERIMENTAL AND THEORETICAL INVESTIGATION OF A HORIZONTAL-AXIS WIND TURBINE A Thesis by ROBERT TERRANCE MILBURN Submitted to the Graduate College of Texas A&M University in partial fulfillment of the requirement for the degree of MASTER... OF SCIENCE August 1977 Major Subject: Aerospace Engineering THE EXPERIMENTAL AND THEORETICAL INVESTIGATION OF A HORIZONTAL-AXIS WIND TURBINE A Thesis by ROBERT TERRANCE MILBURN Approved as to style and content by: (Chairman of Committee) (Head...
Method for non-contact particle manipulation and control of particle spacing along an axis
Goddard, Gregory Russ; Kaduchak, Gregory; Jett, James Hubert; Graves, Steven Wayde
2012-09-11T23:59:59.000Z
Method and system for uniformly spacing particles in a flowing system comprising suspending particles in an elongated fluid filled cavity; exposing said cavity to an axial acoustic standing wave field, wherein said axial acoustic standing wave field drives said particles to nodal and anti-nodal positions along the center axis of said cavity to result in uniformly spaced particles; and focusing said particles to the center axis of said cavity.
First Measurement of $?_?$ and $?_e$ Events in an Off-Axis Horn-Focused Neutrino Beam
P. Adamson; A. A. Aguilar-Arevalo; C. E. Anderson; A. O. Bazarko; M. Bishai; S. J. Brice; B. C. Brown; L. Bugel; J. Cao; B. C. Choudhary; L. Coney; J. M. Conrad; D. C. Cox; A. Curioni; Z. Djurcic; D. A. Finley; B. T. Fleming; R. Ford; H. R. Gallagher; F. G. Garcia; G. T. Garvey; C. Green; J. A. Green; D. Harris; T. L. Hart; E. Hawker; J. Hylen; R. Imlay; R. A. Johnson; G. Karagiorgi; P. Kasper; T. Katori; T. Kobilarcik; S. Kopp; I. Kourbanis; S. Koutsoliotas; E. M. Laird; S. K. Linden; J. M. Link; Y. Liu; Y. Liu; L. Loiacono; W. C. Louis; A. Marchionni; K. B. M. Mahn; W. Marsh; G. McGregor; M. D. Messier; W. Metcalf; P. D. Meyers; F. Mills; G. B. Mills; J. Monroe; C. D. Moore; J. K. Nelson; R. H. Nelson; V. T. Nguyen; P. Nienaber; J. A. Nowak; S. Ouedraogo; R. B. Patterson; Z. Pavlovic; D. Perevalov; C. C. Polly; E. Prebys; J. L. Raaf; H. Ray; B. P. Roe; A. D. Russell; V. Sandberg; R. Schirato; D. Schmitz; M. H. Shaevitz; F. C. Shoemaker; W. Smart; D. Smith; M. Sodeberg; M. Sorel; P. Spentzouris; I. Stancu; R. J. Stefanski; M. Sung; H. A. Tanaka; R. Tayloe; M. Tzanov; P. Vahle; R. Van de Water; B. Viren; M. O. Wascko; D. H. White; M. J. Wilking; H. J. Yang; F. X. Yumiceva; G. P. Zeller; E. D. Zimmerman; R. Zwaska
2009-07-21T23:59:59.000Z
We report the first observation of off-axis neutrino interactions in the MiniBooNE detector from the NuMI beamline at Fermilab. The MiniBooNE detector is located 745 m from the NuMI production target, at 110 mrad angle ($6.3^{\\circ}$) with respect to the NuMI beam axis. Samples of charged current quasi-elastic $\
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)
2014-11-01T23:59:59.000Z
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.
Role of Brownian motion hydrodynamics on nanofluid thermal conductivity William Evans
Fish, Jacob
Role of Brownian motion hydrodynamics on nanofluid thermal conductivity William Evans Lockheed of solid nanoparticles nanofluids to demonstrate that the hydrodynamics effects associated with Brownian motion have only a minor effect on the thermal conductivity of the nanofluid. This analysis is supported
Alvaro Domínguez
2014-10-10T23:59:59.000Z
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.
THERMO-HYDRODYNAMICS OF DEVELOPING FLOW IN A RECTANGULAR MINI-CHANNEL ARRAY Gaurav Agarwal
Khandekar, Sameer
THERMO-HYDRODYNAMICS OF DEVELOPING FLOW IN A RECTANGULAR MINI-CHANNEL ARRAY Gaurav Agarwal Dept of Technology Kanpur Kanpur (UP) 208016, India samkhan@iitk.ac.in ABSTRACT Thermo-hydrodynamic performance on developing flows. Thus, the study reveals that conventional theory, which predicts thermo
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
2015-01-01T23:59:59.000Z
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
Price, Jeffery R.; Bingham, Philip R.
2005-11-08T23:59:59.000Z
Systems and methods are described for rapid acquisition of fused off-axis illumination direct-to-digital holography. A method of recording a plurality of off-axis object illuminated spatially heterodyne holograms, each of the off-axis object illuminated spatially heterodyne holograms including spatially heterodyne fringes for Fourier analysis, includes digitally recording, with a first illumination source of an interferometer, a first off-axis object illuminated spatially heterodyne hologram including spatially heterodyne fringes for Fourier analysis; and digitally recording, with a second illumination source of the interferometer, a second off-axis object illuminated spatially heterodyne hologram including spatially heterodyne fringes for Fourier analysis.
Absolute Lineshifts - A new diagnostic for stellar hydrodynamics
Dainis Dravins
2003-02-28T23:59:59.000Z
For hydrodynamic model atmospheres, absolute lineshifts are becoming an observable diagnostic tool beyond the classical ones of line-strength, -width, -shape, and -asymmetry. This is the wavelength displacement of different types of spectral lines away from the positions naively expected from the Doppler shift caused by stellar radial motion. Caused mainly by correlated velocity and brightness patterns in granular convection, such absolute lineshifts could in the past be studied only for the Sun (since the relative Sun-Earth motion, and the ensuing Doppler shift is known). For other stars, this is now becoming possible thanks to three separate developments: (a) Astrometric determination of stellar radial motion; (b) High-resolution spectrometers with accurate wavelength calibration, and (c) Accurate laboratory wavelengths for several atomic species. Absolute lineshifts offer a tool to segregate various 2- and 3-dimensional models, and to identify non-LTE effects in line formation.
Absolute Lineshifts - A new diagnostic for stellar hydrodynamics
Dravins, D
2003-01-01T23:59:59.000Z
For hydrodynamic model atmospheres, absolute lineshifts are becoming an observable diagnostic tool beyond the classical ones of line-strength, -width, -shape, and -asymmetry. This is the wavelength displacement of different types of spectral lines away from the positions naively expected from the Doppler shift caused by stellar radial motion. Caused mainly by correlated velocity and brightness patterns in granular convection, such absolute lineshifts could in the past be studied only for the Sun (since the relative Sun-Earth motion, and the ensuing Doppler shift is known). For other stars, this is now becoming possible thanks to three separate developments: (a) Astrometric determination of stellar radial motion; (b) High-resolution spectrometers with accurate wavelength calibration, and (c) Accurate laboratory wavelengths for several atomic species. Absolute lineshifts offer a tool to segregate various 2- and 3-dimensional models, and to identify non-LTE effects in line formation.
Anisotropic flow in transport+hydrodynamics hybrid approaches
Hannah Petersen
2014-11-26T23:59:59.000Z
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.
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)
2013-08-15T23:59:59.000Z
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.
Hydrodynamic transport coefficients in relativistic scalar field theory
Jeon, S. [Department of Physics FM-15, University of Washington, Seattle, Washington 98195 (United States)] [Department of Physics FM-15, University of Washington, Seattle, Washington 98195 (United States)
1995-09-15T23:59:59.000Z
Hydrodynamic transport coefficients may be evaluated from first principals in a weakly coupled scalar field theory at an arbitrary temperature. In a theory with cubic and quartic interactions, the infinite class of diagrams which contributes to the leading weak coupling behavior is identified and summed. The resulting expression may be reduced to a single linear integral equation, which is shown to be identical to the corresponding result obtained from a linearized Boltzmann equation describing effective thermal excitations with temperature-dependent masses and scattering amplitudes. The effective Boltzmann equation is valid even at very high temperature where the thermal lifetime and mean free path are short compared to the Compton wavelength of the fundamental particles. Numerical results for the shear and the bulk viscosities are presented.
An Eulerian PPM & PIC Code for Cosmological Hydrodynamics
A. Sornborger; B. Fryxell; K. Olson; P. MacNeice
1996-08-05T23:59:59.000Z
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.
Hydrodynamics of the physical vacuum: dark matter is an illusion
Valeriy I. Sbitnev
2015-06-23T23:59:59.000Z
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.
Hydro-dynamical models for the chaotic dripping faucet
P. Coullet; L. Mahadevan; C. S. Riera
2004-08-20T23:59:59.000Z
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.
Hydrodynamics of the physical vacuum: dark matter is an illusion
Sbitnev, Valeriy I
2015-01-01T23:59:59.000Z
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
2014-10-01T23:59:59.000Z
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.
A Co-moving Coordinate System for Relativistic Hydrodynamics
Scott Pratt
2006-12-03T23:59:59.000Z
The equations of relativistic hydrodynamics are transformed so that steps forward in time preserves local simultaneity. In these variables, the space-time coordinates of neighboring points on the mesh are simultaneous according to co-moving observers. Aside from the time step varying as a function of the location on the mesh, the local velocity gradient and the local density then evolve according to non-relativistic equations of motion. Analytic solutions are found for two one-dimensional cases with constant speed of sound. One solution has a Gaussian density profile when mapped into the new coordinates. That solution is analyzed for the effects of longitudinal acceleration in relativistic heavy ion collisions at RHIC, especially in regards to two-particle correlation measurements of the longitudinal size.
Cheng, X.; Wang, Z. G.; Kobayashi, S.; Nakamoto, K.; Yamazaki, K.
2010-01-01T23:59:59.000Z
nano milling—function analysis and design of a six-axis Wirepaper, a function analysis and design of a six-axis Wireon the function analysis and design of a six-axis WEDM
Simulated VLBI Images From Relativistic Hydrodynamic Jet Models
Amy J. Mioduszewski; Philip A. Hughes; G. Comer Duncan
1996-06-03T23:59:59.000Z
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.
Impact of hydrodynamics on coal liquefaction. Final technical report
Kang, D.; Ying, D.H.S.; Givens, E.N.
1983-09-01T23:59:59.000Z
We have attempted to determine the hydrodynamic effects of various reactor configurations on coal liquefaction, to help select the optimal reactor configuration and to provide additional understanding of coal liquefaction reaction kinetics, which cannot be definitively determined by a CSTR alone. Only a qualitative understanding of the fluid dynamic effects on product yields has been perceived by operating various sizes of open-column tubular reactors, because the fluid-dynamic characteristics of these reactors were not clearly understood and could not be varied significantly. Indirect studies, by cold-flow simulation, have been of little help in defining the fluid dynamic impact on coal liquefaction. Comparison of actual coal liquefaction data from both the plug-flow reactor and the CSTR showed that the plug-flow configuration had various advantages. Reactor yields improved significantly, especially the primary product conversions. At 840/sup 0/F and residence times of 29 and 40 min, coal and preasphaltene conversions were enhanced approximately 6 and 10%, respectively. At these conditions, the plug-flow reactor also yielded about 10% more oils than the CSTR with significant increase in hydrogen utilization. Also, this study provided an opportunity to examine the soundness of APCI/ICRC's sequential kinetic model, by interfacing the plug-flow and CSTR yield data. Transforming CSTR yields to plug-flow data showed that product yields deviated considerably from the measured plug-flow data, suggesting the need to improve the existing reaction model. Having both CSTR and plug-flow reactor data bases is important for developing a sound coal reaction model and for determining hydrodynamic effects on coal liquefaction in a direct way. The results will lead to an optimized reactor configuration as well as optimized operation. 5 references, 23 figures, 20 tables.
Rajarshi Chakrabarti
2011-05-04T23:59:59.000Z
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)).
Effect of Second-Order Hydrodynamics on a Floating Offshore Wind Turbine
Roald, L.; Jonkman, J.; Robertson, A.
2014-05-01T23:59:59.000Z
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.
Introduction and guide to LLNL's relativistic 3-D nuclear hydrodynamics code
Zingman, J.A.; McAbee, T.L.; Alonso, C.T.; Wilson, J.R.
1987-11-01T23:59:59.000Z
We have constructed a relativistic hydrodynamic model to investigate Bevalac and higher energy, heavy-ion collisions. The basis of the model is a finite-difference solution to covariant hydrodynamics, which will be described in the rest of this paper. This paper also contains: a brief review of the equations and numerical methods we have employed in the solution to the hydrodynamic equations, a detailed description of several of the most important subroutines, and a numerical test on the code. 30 refs., 8 figs., 1 tab.
Supanich, M [Rush University Medical Center, Chicago, IL (United States); Bevins, N [Henry Ford Health System, Detroit, MI (United States)
2014-06-01T23:59:59.000Z
Purpose: This review of scanners from 4 major manufacturers examines the clinical impact of performing CT scans that extend into areas of the body that were not acquired in the CT localizer radiograph. Methods: Anthropomorphic chest and abdomen phantoms were positioned together on the tables of CT scanners from 4 different vendors. All of the scanners offered an Automatic Exposure Control (AEC) option with both lateral and axial tube current modulation. A localizer radiograph was taken covering the entire extent of both phantoms and then the scanner's Chest-Abdomen-Pelvis (CAP) study was performed with the clinical AEC settings employed and the scan and reconstruction range extending from the superior portion of the chest phantom through the inferior portion of the abdomen phantom. A new study was then initiated with a localizer radiograph extending the length of the chest phantom (not covering the abdomen phantom). The same CAP protocol and AEC settings were then used to scan and reconstruct the entire length of both phantoms. Scan parameters at specific locations in the abdomen phantom from both studies were investigated using the information contained in the DICOM metadata of the reconstructed images. Results: The AEC systems on all scanners utilized different tube current settings in the abdomen phantom for the scan completed without the full localizer radiograph. The AEC system behavior was also scanner dependent with the default manual tube current, the maximum tube current and the tube current at the last known position observed as outcomes. Conclusion: The behavior of the AEC systems of CT scanners in regions not covered by the localizer radiograph is vendor dependent. To ensure optimal image quality and radiation exposure it is important to include the entire planned scan region in the localizer radiograph.
The chemical enrichment of the ICM from hydrodynamical simulations
S. Borgani; D. Fabjan; L. Tornatore; S. Schindler; K. Dolag; A. Diaferio
2008-01-07T23:59:59.000Z
The study of the metal enrichment of the intra-cluster and inter-galactic media (ICM and IGM) represents a direct means to reconstruct the past history of star formation, the role of feedback processes and the gas-dynamical processes which determine the evolution of the cosmic baryons. In this paper we review the approaches that have been followed so far to model the enrichment of the ICM in a cosmological context. While our presentation will be focused on the role played by hydrodynamical simulations, we will also discuss other approaches based on semi-analytical models of galaxy formation, also critically discussing pros and cons of the different methods. We will first review the concept of the model of chemical evolution to be implemented in any chemo-dynamical description. We will emphasise how the predictions of this model critically depend on the choice of the stellar initial mass function, on the stellar life-times and on the stellar yields. We will then overview the comparisons presented so far between X-ray observations of the ICM enrichment and model predictions. We will show how the most recent chemo-dynamical models are able to capture the basic features of the observed metal content of the ICM and its evolution. We will conclude by highlighting the open questions in this study and the direction of improvements for cosmological chemo-dynamical models of the next generation.
Simulating Magnetized Laboratory Plasmas with Smoothed Particle Hydrodynamics
Johnson, J N
2009-07-02T23:59:59.000Z
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.
Radiation Hydrodynamical Evolution of Primordial H II Regions
Daniel Whalen; Tom Abel; Michael L. Norman
2004-03-02T23:59:59.000Z
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.
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)
2014-12-01T23:59:59.000Z
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.
IUTAM symposium on hydrodynamic diffusion of suspended particles
Davis, R.H. [ed.
1995-12-31T23:59:59.000Z
Hydrodynamic diffusion refers to the fluctuating motion of nonBrownian particles (or droplets or bubbles) which occurs in a dispersion due to multiparticle interactions. For example, in a concentrated sheared suspension, particles do not move along streamlines but instead exhibit fluctuating motions as they tumble around each other. This leads to a net migration of particles down gradients in particle concentration and in shear rate, due to the higher frequency of encounters of a test particle with other particles on the side of the test particle which has higher concentration or shear rate. As another example, suspended particles subject to sedimentation, centrifugation, or fluidization, do not generally move relative to the fluid with a constant velocity, but instead experience diffusion-like fluctuations in velocity due to interactions with neighboring particles and the resulting variation in the microstructure or configuration of the suspended particles. In flowing granular materials, the particles interact through direct collisions or contacts (rather than through the surrounding fluid); these collisions also cause the particles to undergo fluctuating motions characteristic of diffusion processes. Selected papers are indexed separately for inclusion in the Energy Science and Technology Database.
Design of an electromagnetic accelerator for turbulent hydrodynamic mix studies
Susoeff, A.R.; Hawke, R.S.; Morrison, J.J.; Dimonte, G.; Remington, B.A.
1993-12-08T23:59:59.000Z
An electromagnetic accelerator in the form of a linear electric motor (LEM) has been designed to achieve controlled acceleration profiles of a carriage containing hydrodynamically unstable fluids for the investigation of the development of turbulent mix. The Rayleigh- Taylor instability is investigated by accelerating two dissimilar density fluids using the LEM to achieve a wide variety of acceleration and deceleration profiles. The acceleration profiles are achieved by independent control of rail and augmentation currents. A variety of acceleration-time profiles are possible including: (1) constant, (2) impulsive and (3) shaped. The LEM and support structure are a robust design in order to withstand high loads with deflections and to mitigate operational vibration. Vibration of the carriage during acceleration could create artifacts in the data which would interfere with the intended study of the Rayleigh-Taylor instability. The design allows clear access for diagnostic techniques such as laser induced fluorescence radiography, shadowgraphs and particle imaging velocimetry. Electromagnetic modeling codes were used to optimize the rail and augmentation coil positions within the support structure framework. Results of contemporary studies for non-arcing sliding contact of solid armatures are used for the design of the driving armature and the dynamic electromagnetic braking system. A 0. 6MJ electrolytic capacitor bank is used for energy storage to drive the LEM. This report will discuss a LEM design which will accelerate masses of up to 3kg to a maximum of about 3000g{sub o}, where g{sub o} is accelerated due to gravity.
MODEST: modeling stellar evolution and (hydro)dynamics
Piet Hut
2003-09-15T23:59:59.000Z
Simulations of dense stellar systems currently face two major hurdles, one astrophysical and one computational. The astrophysical problem lies in the fact that several major stages in binary evolution, such as common envelope evolution, are still poorly understood. The best we can do in these cases is to parametrize our ignorance, in a way that is reminiscent of the introduction of a mixing length to describe convection in a single star, or an alpha parameter in modeling an accretion disk. The hope is that by modeling a whole star cluster in great detail, and comparing the results to the wealth of observational data currently available, we will be able to constrain the parameters that capture the unknown physics. The computational problem is one of composition: while we have accurate computer codes for modeling stellar dynamics, stellar hydrodynamics, and stellar evolution, we currently have no good way to put all this knowledge together in a single software environment. A year ago, a loosely-knit organization was founded to address these problems, MODEST for MOdeling DEnse STellar systems, with nine working groups and a series of meetings that are held every half year. This report reviews the first year of this initiative. Much more detail can be found on the MODEST web site http://www.manybody.org/modest.html .
Thermal and hydrodynamic effects in the ordering of lamellar fluids
G. Gonnella; A. Lamura; A. Tiribocchi
2011-02-15T23:59:59.000Z
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.
Driven cavity flow: from molecular dynamics to continuum hydrodynamics
Tiezheng Qian; Xiao-Ping Wang
2004-03-06T23:59:59.000Z
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.
Onset and cessation of motion in hydrodynamically sheared granular beds
Abram H. Clark; Mark D. Shattuck; Nicholas T. Ouellette; Corey S. O'Hern
2015-04-14T23:59:59.000Z
To clarify the grain-scale mechanisms that control the onset and cessation of sediment transport, we performed molecular dynamics simulations of granular beds driven by a model hydrodynamic shear flow. We find a critical value for the Shields number (the nondimensional shear stress at the top of the granular bed) that separates flowing and static states, with a bed flow rate that is discontinuous at the critical value. The transition times between flowing and static states diverge as the system approaches the critical Shields number from above and below. Additionally we find that, for finite systems, the onset of flow occurs stochastically at supercritical Shields numbers. We show that the statistics of the Shields number at failure obey Weibullian weakest-link statistics, and that the onset of flow is caused by local grain rearrangements that give rise to additional rearrangements and then to continuous flow. Thus, the onset of motion is governed by the packing structure of the granular bed, even deep beneath the surface. Since the fluid dynamics is strongly coupled to the settling process and thus to the bed structure, this also suggests a strong feedback between the fluid dynamics and granular physics in bed mobilization.
Entropy production in non-equilibrium fluctuating hydrodynamics
Giacomo Gradenigo; Andrea Puglisi; Alessandro Sarracino
2012-05-16T23:59:59.000Z
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.
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
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 ...
A Smoothed Particle Hydrodynamics-Based Fluid Model With a Spatially...
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
A Smoothed Particle Hydrodynamics-Based Fluid Model With a Spatially Dependent Viscosity Authors: Martys, N.S., George, W.L., Chun, B., Lootens, D. A smoothed particle...
Venkataraman, Balaji
1995-01-01T23:59:59.000Z
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...
Energy Conversion Efficiency of Nanofluidic Batteries: Hydrodynamic Slip and Access Resistance
Chang, Hsueh-Chia
Energy Conversion Efficiency of Nanofluidic Batteries: Hydrodynamic Slip and Access Resistance Yu channels. INTRODUCTION Nanofluidic batteries are interesting energy generation systems for converting with this nanofluidic battery system has gained considerable attention. One of the challenges for the nanofluidic
Pandoe, Wahyu Widodo
2004-09-30T23:59:59.000Z
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...
Anderson, Mary Elizabeth
2011-10-21T23:59:59.000Z
nor implemented in current hydrodynamic models. A series of laboratory experiments were conducted at the Haynes Coastal Engineering Laboratory and in a two-dimensional flume at Texas A and M University to investigate the influence of relative...
Using Genetic Algorithms to Optimize Bathymetric Surveys for Hydrodynamic Model Input
Manian, Dinesh
2010-07-14T23:59:59.000Z
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...
Matha, D.; Schlipf, M.; Cordle, A.; Pereira, R.; Jonkman, J.
2011-10-01T23:59:59.000Z
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.
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
2012-10-01T23:59:59.000Z
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.
Physico-chemical hydrodynamics of droplets on textured surfaces with engineered micro/nanostructures
Park, Kyoo Chul
2013-01-01T23:59:59.000Z
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 ...
Design of the All-Electric Ship: Focus on Integrated Power System Coupled to Hydrodynamics
Prempraneerach, P.
2008-01-01T23:59:59.000Z
We present a detailed model of the integrated power system coupled to hydrodynamics that allows us to study global sensitivities in the All-Electric Ship. A novel element of our formulation is the stochastic modeling of ...
A model for analyzing the effects of hydrodynamic forces on cell adhesion in a perfused bioreactor
Owens, Bryan D
2007-01-01T23:59:59.000Z
In bioreactor culture systems that aim to provide a convective flux to address mass transport limitations of oxygen and other nutrients, large hydrodynamic forces and shear stress can potentially serve as a negative signals ...
Mendelson, Leah Rose
2013-01-01T23:59:59.000Z
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 ...
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
Anderson, Mary Elizabeth
2011-10-21T23:59:59.000Z
nor implemented in current hydrodynamic models. A series of laboratory experiments were conducted at the Haynes Coastal Engineering Laboratory and in a two-dimensional flume at Texas A and M University to investigate the influence of relative...
CFD study of hydrodynamic signal perception by fish using the lateral line system
Rapo, Mark Andrew
2009-01-01T23:59:59.000Z
The lateral line system on fish has been found to aid in schooling behavior, courtship communication, active and passive hydrodynamic imaging, and prey detection. The most widely used artificial prey stimulus has been the ...
Measurements of static loading characteristics of a Flexurepivot Tilt Pad Hydrodynamic Bearing
Walton, Nicholas Van Edward
1995-01-01T23:59:59.000Z
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...
Measurements of static loading characteristics of a Flexurepivot Tilt Pad Hydrodynamic Bearing
Walton, Nicholas Van Edward
1995-01-01T23:59:59.000Z
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...
William H. Lee
2000-07-14T23:59:59.000Z
We present a hydrodynamical study of the final stages of inspiral in a black hole-neutron star (NS) binary. We use a Newtonian 3D SPH code, and model the NS with a stiff (index G=3 and G=2.5) polytropic equation of state and the black hole as a Newtonian point mass. Our initial conditions correspond to irrotational binaries in equilibrium (approximating the NS as a compressible ellipsoid), and we have explored configurations with different initial mass ratios, 0.2< q=M_ns/M_bh<0.5. The dynamical evolution is followed for ~23ms. We include gravitational radiation losses in the quadrupole approximation for a point-mass binary. For G=3, after an initial episode of mass transfer, the NS is not completely disrupted and a remnant core remains in orbit about the black hole. For G=2.5 the disruption is more complex, with the NS being totally disrupted during a second periastron passage. The accretion disc formed around the black hole contains ~0.2 solar masses. A nearly baryon-free axis is always present in the system, and only modest beaming of a relativistic fireball that could give rise to a GRB would be sufficient to avoid baryon contamination. Around 0.01 solar masses may be dynamically ejected from the system, and could contribute substantially to the amount of observed galactic r-process material. We calculate the gravitational radiation waveforms in the quadrupole approximation. We also present the results of simulations that have used spherical NSs relaxed in isolation as initial conditions, in order to gauge the effect of using non-equilibrium initial conditions on the coalescence.
Bicknell, James Scott
1985-01-01T23:59:59.000Z
DEPOSITIONAL ENVIRONMENT AND HYDRODYNAMIC FLOW IN LOWER CRETACEOUS J SANDSTONE, LONETREE FIELD, DENVER BASIN, COLORADO A Thesis by JAMES SCOTT BICKNELL Submitted to the Graduate College of Texas A&M University in partial fulfillment... of the requirement for the degree of MASTER OF SCIENCE December 1985 Major Subject: Geology DEPOSITIONAL ENVIRONMENT AND HYDRODYNAMIC FLOW IN LOWER CRETACEOUS J SANDSTONE, LONETREE FIELD, DENVER BASIN, COLORADO A Thesis by JAMES SCOTT BICKNELL Approved...
Test plan for the 34 meter vertical axis wind turbine test bed located at Bushland, Texas
Stephenson, W.A.
1986-12-01T23:59:59.000Z
A plan is presented for the testing and evaluation of a new 500 kw vertical axis wind turbine test bed. The plan starts with the initial measurements made during construction, proceeds through evaluation of the design, the development of control methods, and finally to the test bed phase where new concepts are evaluated and in-depth studies are performed.
Russell, J. A.; Ochedalski, T; Meddle, S. L.; Ma, S.; Brunton, P. J.; Douglas, A. J.
2005-01-01T23:59:59.000Z
, but not pregnant, rats. However, naloxone infused directly into the PVN increased noradrenaline release after IL-1{beta} in pregnant rats. Thus, the HPA axis responses to immune signals are suppressed in pregnancy at the level of pPVN CRH neurons through an opioid...
Correlating anomalies of the microwave sky: The Good, the Evil and the Axis
Aleksandar Rakic; Dominik J. Schwarz
2007-05-11T23:59:59.000Z
At the largest angular scales the presence of a number of unexpected features has been confirmed by the latest measurements of the cosmic microwave background (CMB). Among them are the anomalous alignment of the quadrupole and octopole with each other as well as the stubborn lack of angular correlation on scales >60deg. We search for correlations between these two phenomena and demonstrate their absence. A Monte Carlo likelihood analysis confirms previous studies and shows that the joint likelihood of both anomalies is incompatible with the best-fit Lambda Cold Dark Matter model at >99.95% C.L. At the same time, a presumed special axis (the `Axis of Evil') identified on the microwave sky demands additional contributions to multipole power on top of the primordial standard inflationary ones. We find that the notion of a preferred axis in the CMB is misleading and inconsistent with three-year data from the Wilkinson Microwave Anisotropy Probe (WMAP). Rather the data require a preferred plane, whereupon the axis is just the normal direction to that plane. Rotational symmetry within that plane is inconsistent with the observations and is ruled out at high confidence.
MAGNETIC NEUTRON SCATTERING. And Recent Developments in the Triple Axis Spectroscopy
Johnson, Peter D.
Chapter 1 MAGNETIC NEUTRON SCATTERING. And Recent Developments in the Triple Axis Spectroscopy Igor.................................................................................... 2 2. Neutron interaction with matter and scattering cross-section ........ 6 2.1 Basic scattering theory and differential cross-section................ 7 2.2 Neutron interactions and scattering lengths
First-order design of off-axis reflective ophthalmic adaptive optics systems using afocal
First-order design of off-axis reflective ophthalmic adaptive optics systems using afocal for designing laser cavities, spectrographs and adaptive optics retinal imaging systems. The use, range respectively. This is discussed using examples from adaptive optics retinal imaging systems. The performance
Axis control using model predictive control: identification and friction effect reduction
Boyer, Edmond
Axis control using model predictive control: identification and friction effect reduction Pedro this numerical model is used to synthetize a predictive GPC controller reducing the impact of the friction Rodriguez-Ayerbe, Didier Dumur, Sylvain Lavernhe** * SUPELEC- E3S, Automatic Control, 3 rue Joliot Curie
Extremely Soft X-ray Flash as the indicator of off-axis orphan GRB afterglow
Urata, Yuji; Yamazaki, Ryo; Sakamoto, Takanori
2015-01-01T23:59:59.000Z
We verified the off-axis jet model of X-ray flashes (XRFs) and examined a discovery of off-axis orphan gamma-ray burst (GRBs) afterglows. The XRF sample was selected on the basis of the following three factors: (1) a constraint on the lower peak energy of the prompt spectrum $E^{src}_{obs}$, (2) redshift measurements, and (3) multi-color observations of an earlier (or brightening) phase. XRF020903 was the only sample selected basis of these criteria. A complete optical multi-color afterglow light curve of XRF020903 obtained from archived data and photometric results in literature showed an achromatic brightening around 0.7 days. An off-axis jet model with a large observing angle (0.21 rad, which is twice the jet opening half-angle, $\\theta_{jet}$) can naturally describe the achromatic brightening and the prompt X-ray spectral properties. This result indicates the existence of off-axis orphan GRB afterglow light curves. Events with a larger viewing angle ($>\\sim2\\theta_{jet}$) could be discovered using an 8-m ...
Rotation Angle for the Optimum Tracking of One-Axis Trackers
Marion, W. F.; Dobos, A. P.
2013-07-01T23:59:59.000Z
An equation for the rotation angle for optimum tracking of one-axis trackers is derived along with equations giving the relationships between the rotation angle and the surface tilt and azimuth angles. These equations are useful for improved modeling of the solar radiation available to a collector with tracking constraints and for determining the appropriate motor revolutions for optimum tracking.
1-and 2-Axis Magnetic Sensors HMC1001/1002/1021/1022
Kleinfeld, David
1- and 2-Axis Magnetic Sensors HMC1001/1002/1021/1022 The Honeywell HMC100x and HMC102x magnetic and HMC102x sensors utilize Honeywell's Anisotropic Magnetoresistive (AMR) technology that provides-gauss to 6 gauss. Honeywell's Magnetic Sensors are among the most sensitive and reliable low-field sensors
Integral operators with the generalized sine-kernel on the real axis
N. A. Slavnov
2010-05-27T23:59:59.000Z
The asymptotic properties of integral operators with the generalized sine kernel acting on the real axis are studied. The formulas for the resolvent and the Fredholm determinant are obtained in the large x limit. Some applications of the results obtained to the theory of integrable models are considered.
Origin of a magnetic easy axis in pipeline steel L. Clapham,a)
Clapham, Lynann
Origin of a magnetic easy axis in pipeline steel L. Clapham,a) C. Heald, T. Krause, and D. L December 1998; accepted for publication 27 April 1999 Oil and gas pipelines are generally magnetically overlooked, the magnetic properties of oil and gas pipelines are an important consideration since the most
Vertical-axis Wind Turbines: Development of the Offshore Wind Energy Simulation Toolkit Brian C. Owens The availability of offshore wind resources in coastal regions makes offshore wind energy an attractive opportunity. There are, however, significant challenges in realizing offshore wind energy with an acceptable cost
Digital Design and Fabrication Techniques Using a 3-Axis CNC Mill
Coffman, Ky
2010-07-14T23:59:59.000Z
of their inability to rotate out of the z-axis to make undercuts. We investigated different fabrication techniques that can be used to create completely three-dimensional forms with this machine and poly-urethane foam. Included in the fabrication process...
Axis-Aligned Filtering for Interactive Physically-Based Diffuse Indirect Lighting Soham Uday Mehta1
O'Brien, James F.
-bounce indirect lighting, Our Method average 63 samples per pixel (spp) (b) Adaptive Sampling, based on a novel frequency analysis of indirect lighting. Our method combines adaptive sampling by MonteAxis-Aligned Filtering for Interactive Physically-Based Diffuse Indirect Lighting Soham Uday Mehta1
On the probability of major-axis precession in triaxial ellipsoidal potentials
P. A. Thomas; S. Vine; F. R. Pearce
1993-08-09T23:59:59.000Z
Orbits in triaxial ellipsoidal potentials precess about either the major or minor axis of the ellipsoid. In standard perturbation theory it can be shown that a circular orbit will precess about the minor axis if its angular momentum vector lies in a region bounded by two great circles which pass through the intermediate axis and which are inclined with minimum separation $i_T$ from the minor axis. We test the accuracy of the standard formula for $i_T$ by performing orbit integrations to determine $i_S$, the simulated turnover angle corresponding to $i_T$. We reach two principal conclusions: (i) $i_S$ is usually greater than $i_T$, by as much as 12 degrees even for moderate triaxialities, $A/1.2
Calibration of Multi-Axis MEMS Force Sensors Using the Shape from Motion Method
Sun, Yu
Calibration of Multi-Axis MEMS Force Sensors Using the Shape from Motion Method Yu Sun, Keekyoung Inst. of Robotics and Intelligent Systems University of Toronto University of Minnesota Swiss Federal systems) capacitive force sensor with strict linearity and a new sensor calibration method for micro-sensors
Method for non-contact particle manipulation and control of particle spacing along an axis
Goddard, Gregory Russ; Kaduchak, Gregory; Jett, James Hubert; Graves, Steven Wayde
2013-09-10T23:59:59.000Z
One or more of the embodiments of the present invention provide for a method of non-contact particle manipulation and control of particle spacing along an axis which includes axial and radial acoustic standing wave fields. Particles are suspended in an aqueous solution, and this solution then flows into the cylindrical flow channel. While the solution flows through the flow channel, the outer structure of the flow channel is vibrated at a resonant frequency, causing a radial acoustic standing wave field to form inside the flow channel in the solution. These radial acoustic standing waves focus the particles suspended in the solution to the center axis of the cylindrical flow channel. At the same time, a transducer is used to create an axial acoustic standing wave field in the flow channel parallel to the axis of the flow channel. This drives the particles, which are already being focused to the center axis of the flow channel, to nodes or anti-nodes of the axial standing wave at half-wavelength intervals, depending on whether the particles are more or less dense and more or less compressible than the surrounding fluid.
Automatic polishing process of plastic injection molds on a 5-axis milling center
Xavier Pessoles; Christophe Tournier
2010-03-26T23:59:59.000Z
The plastic injection mold manufacturing process includes polishing operations when surface roughness is critical or mirror effect is required to produce transparent parts. This polishing operation is mainly carried out manually by skilled workers of subcontractor companies. In this paper, we propose an automatic polishing technique on a 5-axis milling center in order to use the same means of production from machining to polishing and reduce the costs. We develop special algorithms to compute 5-axis cutter locations on free-form cavities in order to imitate the skills of the workers. These are based on both filling curves and trochoidal curves. The polishing force is ensured by the compliance of the passive tool itself and set-up by calibration between displacement and force based on a force sensor. The compliance of the tool helps to avoid kinematical error effects on the part during 5-axis tool movements. The effectiveness of the method in terms of the surface roughness quality and the simplicity of implementation is shown through experiments on a 5-axis machining center with a rotary and tilt table.
Microstructure dependence of the c-axis critical current density in second-generation YBCO tapes.
Jia, Y.; Welp, U.; Crabtree, G. W.; Kwok, W. K.; Malozemoff, A. P.; Rupich, M. W.; Fleshler, S.; Clem, J. R. (Materials Science Division); (American Superconductor Corp.); (Ames Lab.); (Iowa State Univ.)
2011-10-01T23:59:59.000Z
C-axis current flow in high temperature superconductor (HTS) tape-shaped wires arises in configurations where the local wire axis is not perpendicular to the local magnetic field, such as in power cables with helically wound HTS tapes. The c-axis critical current density J{sub c}{sup c} has been recently found to be orders of magnitude lower than the ab-plane critical current density J{sub c}{sup ab}. Here we report on J{sub c}{sup c} (77 K, sf) values of various YBa{sub 2}Cu{sub 3}O{sub 7}-based (YBCO) tapes with different microstructures. Our results show that the value of J{sub c}{sup c} (77 K, sf) decreases significantly with increasing concentration of ab-plane stacking faults in YBCO thin films and that the critical current anisotropy {gamma} = J{sub c}{sup ab}/J{sub c}{sup c} can reach values as high as 2070, implying that in the highest-anisotropy tape, {approx}20% of the tape width carries c-axis current in a helically wound power cable.
Microstructure dependence of the c-axis critical current density in second generation YBCO tapes
Jia, Y. Welp, U. Crabtree, G.W.; Kwok, W.K.; Malozemoff, A.P.; Rupich, M.W.; Fleshler, S.; Clem, J.R.
2011-10-31T23:59:59.000Z
C-axis current flow in high temperature superconductor (HTS) tape-shaped wires arises in configurations where the local wire axis is not perpendicular to the local magnetic field, such as in power cables with helically wound HTS tapes. The c-axis critical current density J{sub c}{sup c} has been recently found to be orders of magnitude lower than the ab-plane critical current density J{sub c}{sup ab}. Here we report on J{sub c}{sup c} (77 K, sf) values of various YBa{sub 2}Cu{sub 3}O{sub 7}-based (YBCO) tapes with different microstructures. Our results show that the value of J{sub c}{sup c} (77 K, sf) decreases significantly with increasing concentration of ab-plane stacking faults in YBCO thin films and that the critical current anisotropy {gamma} = J{sub c}{sup ab}/J{sub c}{sup c} can reach values as high as 2070, implying that in the highest-anisotropy tape, {approx}20% of the tape width carries c-axis current in a helically wound power cable.
Off-axis directional acoustic wave beaming control by an asymmetric rubber heterostructures film
Wang, Ji
Off-axis directional acoustic wave beaming control by an asymmetric rubber heterostructures film rubber heterostructures film deposited on steel plate in water. The rubber heterostructures film at left side and right side are constructed by alternately stacking rubber-1 and rubber-2 film periodically
C. Noel; Y. Busegnies; M. V. Papalexandris; V. Deledicque; A. El Messoudi
2007-05-18T23:59:59.000Z
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.
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)
2014-04-20T23:59:59.000Z
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.
Density Power Spectrum of Compressible Hydrodynamic Turbulent Flows
Jongsoo Kim; Dongsu Ryu
2005-07-26T23:59:59.000Z
Turbulent flows are ubiquitous in astrophysical environments, and understanding density structures and their statistics in turbulent media is of great importance in astrophysics. In this paper, we study the density power spectra, $P_{\\rho}$, of transonic and supersonic turbulent flows through one and three-dimensional simulations of driven, isothermal hydrodynamic turbulence with root-mean-square Mach number in the range of $1 \\la M_{\\rm rms} \\la 10$. From one-dimensional experiments we find that the slope of the density power spectra becomes gradually shallower as the rms Mach number increases. It is because the density distribution transforms from the profile with {\\it discontinuities} having $P_{\\rho} \\propto k^{-2}$ for $M_{\\rm rms} \\sim 1$ to the profile with {\\it peaks} having $P_{\\rho} \\propto k^0$ for $M_{\\rm rms} \\gg 1$. We also find that the same trend is carried to three-dimension; that is, the density power spectrum flattens as the Mach number increases. But the density power spectrum of the flow with $M_{\\rm rms} \\sim 1$ has the Kolmogorov slope. The flattening is the consequence of the dominant density structures of {\\it filaments} and {\\it sheets}. Observations have claimed different slopes of density power spectra for electron density and cold H I gas in the interstellar medium. We argue that while the Kolmogorov spectrum for electron density reflects the {\\it transonic} turbulence of $M_{\\rm rms} \\sim 1$ in the warm ionized medium, the shallower spectrum of cold H I gas reflects the {\\it supersonic} turbulence of $M_{\\rm rms} \\sim$ a few in the cold neutral medium.
Margraf, J
2012-06-12T23:59:59.000Z
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.
Effects of Second-Order Hydrodynamics on a Semisubmersible Floating Offshore Wind Turbine: Preprint
Bayati, I.; Jonkman, J.; Robertson, A.; Platt, A.
2014-07-01T23:59:59.000Z
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.
Dabiri, John O.
Potential order-of-magnitude enhancement of wind farm power density via counter-rotating vertical-axis wind turbine arrays John O. Dabiria) Graduate Aeronautical Laboratories and Bioengineering, California; published online 19 July 2011) Modern wind farms comprised of horizontal-axis wind turbines (HAWTs) require
Shamir, Ron
/microRNA Axis Blocks Melanoma Invasion Program by miR-211 Targeting NUAK1 Rachel E Bell, Mehdi Khaled, Dvir Levy, Transcription Factor/microRNA Axis Blocks Melanoma Invasion Program by miR-211 Targeting NUAK1 Blocks Melanoma Invasion Program by miR-211 Targeting NUAK1 Rachel E. Bella,h , Mehdi Khaledb
Hydrodynamic heave damping estimation and scaling for tension leg platforms
Thiagarajan, K.P.; Troesch, A.W. (Univ. of Michigan, Ann Arbor, MI (United States))
1994-05-01T23:59:59.000Z
Resonant heave excitation of tension leg platform (TLP) tendons is typically of high-frequency and small amplitude. The response of the tendons to this excitation is non-negligible due to a very small drag coefficient of the structure in this mode of oscillation. Small values of the drag force complicate experimental estimation in a laboratory due to the dominating inertial force. Model tests conducted at the University of Michigan investigating the damping experienced by a cylinder of 0.457 m (1.5 ft) diameter and 1.219 m (4.0 ft) draft are described here. The cylinder is vertical and surface-piercing, and oscillates parallel to its axis. The amplitude of the forcing is varied to give a Keulegan-Carpenter (KC) number range of 0.1--1.0. The frequency parameter [beta] is 89236, corresponding to an oscillation frequency of 0.41 Hz. From these experiments, a definite nonlinear trend is observed between the drag force and velocity conflicting with some of the results reported by Huse (1990) and Chakrabarti and Hanna (1991). The heave damping coefficients of individual structural components of a TLP follow different scaling laws. Rules are presented for scaling friction and form drag components from model to full scale. Results from experiments are used to obtain a scaling law for vertical columns of a TLP. Previously published results are used for horizontal pontoons. An example TLP calculation shows that the heave damping ratio of horizontal cylinders is approximately 0.049--0.078 percent, depending upon cylinder shape, and that for vertical cylinders is in the range 0.025--0.171 percent, depending upon KC.
Axi-symmetrical flow reactor for .sup.196 Hg photochemical enrichment
Grossman, Mark W. (Belmont, MA)
1991-01-01T23:59:59.000Z
The present invention is directed to an improved photochemical reactor useful for the isotopic enrichment of a predetermined isotope of mercury, especially, .sup.196 Hg. Specifically, two axi-symmetrical flow reactors were constructed according to the teachings of the present invention. These reactors improve the mixing of the reactants during the photochemical enrichment process, affording higher yields of the desired .sup.196 Hg product. Measurements of the variation of yield (Y) and enrichment factor (E) along the flow axis of these reactors indicates very substantial improvement in process uniformity compared to previously used photochemical reactor systems. In one preferred embodiment of the present invention, the photoreactor system was built such that the reactor chamber was removable from the system without disturbing the location of either the photochemical lamp or the filter employed therewith.
Axi-symmetrical flow reactor for [sup 196]Hg photochemical enrichment
Grossman, M.W.
1991-04-30T23:59:59.000Z
The present invention is directed to an improved photochemical reactor useful for the isotopic enrichment of a predetermined isotope of mercury, especially, [sup 196]Hg. Specifically, two axi-symmetrical flow reactors were constructed according to the teachings of the present invention. These reactors improve the mixing of the reactants during the photochemical enrichment process, affording higher yields of the desired [sup 196]Hg product. Measurements of the variation of yield (Y) and enrichment factor (E) along the flow axis of these reactors indicates very substantial improvement in process uniformity compared to previously used photochemical reactor systems. In one preferred embodiment of the present invention, the photoreactor system was built such that the reactor chamber was removable from the system without disturbing the location of either the photochemical lamp or the filter employed therewith. 10 figures.
Fish schooling as a basis for vertical axis wind turbine farm design
Whittlesey, Robert W; Dabiri, John O
2010-01-01T23:59:59.000Z
Most wind farms consist of horizontal axis wind turbines (HAWTs) due to the high power coefficient (mechanical power output divided by the power of the free-stream air through the turbine cross-sectional area) of an isolated turbine. However when in close proximity to neighbouring turbines, HAWTs suffer from a reduced power coefficient. In contrast, previous research on vertical axis wind turbines (VAWTs) suggests that closely-spaced VAWTs may experience only small decreases (or even increases) in an individual turbine's power coefficient when placed in close proximity to neighbours, thus yielding much higher power outputs for a given area of land. A potential flow model of inter-VAWT interactions is developed to investigate the effect of changes in VAWT spatial arrangement on the array performance coefficient, which compares the expected average power coefficient of turbines in an array to a spatially-isolated turbine. A geometric arrangement based on the configuration of shed vortices in the wake of schooli...
Cheng, Hongguang, E-mail: chenghg7932@gmail.com; Deng, Ning [Institute of Microelectronics, Tsinghua University, Beijing 100084 (China)] [Institute of Microelectronics, Tsinghua University, Beijing 100084 (China)
2013-12-15T23:59:59.000Z
We investigated the influence of thermal agitation on the electric field induced precessional magnetization switching probability with perpendicular easy axis by solving the Fokker-Planck equation numerically with finite difference method. The calculated results show that the thermal agitation during the reversal process crucially influences the switching probability. The switching probability can be achieved is only determined by the thermal stability factor ? of the free layer, it is independent on the device dimension, which is important for the high density device application. Ultra-low error rate down to the order of 10{sup ?9} can be achieved for the device of thermal stability factor ? of 40. Low damping factor ? material should be used for the free layer for high reliability device applications. These results exhibit potential of electric field induced precessional magnetization switching with perpendicular easy axis for ultra-low power, high speed and high density magnetic random access memory (MRAM) applications.
Sun-relative pointing for dual-axis solar trackers employing azimuth and elevation rotations.
Riley, Daniel M.; Hansen, Clifford W.
2014-04-01T23:59:59.000Z
Dual axis trackers employing azimuth and elevation rotations are common in the field of photovoltaic (PV) energy generation. Accurate sun-tracking algorithms are widely available. However, a steering algorithm has not been available to accurately point the tracker away from the sun such that a vector projection of the sun beam onto the tracker face falls along a desired path relative to the tracker face. We have developed an algorithm which produces the appropriate azimuth and elevation angles for a dual axis tracker when given the sun position, desired angle of incidence, and the desired projection of the sun beam onto the tracker face. Development of this algorithm was inspired by the need to accurately steer a tracker to desired sun-relative positions in order to better characterize the electro-optical properties of PV and CPV modules.
Method and apparatus for maintaining equilibrium in a helical axis stellarator
Reiman, A.; Boozer, A.
1984-10-31T23:59:59.000Z
Apparatus for maintaining three-dimensional MHD equilibrium in a plasma contained in a helical axis stellarator includes a resonant coil system, having a configuration such that current therethrough generates a magnetic field cancelling the resonant magnetic field produced by currents driven by the plasma pressure on any given flux surface resonating with the rotational transform of another flux surface in the plasma. Current through the resonant coil system is adjusted as a function of plasma beta.
The experimental and theoretical investigaton of a horizontal-axis wind turbine
Milburn, Robert Terrance
1977-01-01T23:59:59.000Z
. Chevalier An experimental and theoretical investigation of a horizontal-axis wind energy conversion device utilizing straight blades as the force- producing surfaces was conducted. The blades were mounted horizontally between two rotating discs and were... positioned with a mechanical cern system to produce the maximum torque at every point around the revolution. The wind turbine was tested in a 7 x 10 ft low speed wind tunnel. The device converted over 20 percent of the energy available in the wind...
How DARHT Works - the World's Most Powerful X-ray Machine
None
2011-11-06T23:59:59.000Z
The Dual Axis Radiographic Hydrodynamic Test (DARHT) facility at Los Alamos National Laboratory is an essential scientific tool that supports Stockpile Stewardship at the Laboratory. The World's most powerful x-ray machine, it's used to take high-speed images of mock nuclear devices - data that is used to confirm and modify advanced computer codes in assuring the safety, security, and effectiveness of the U.S. nuclear deterrent.
How DARHT Works - the World's Most Powerful X-ray Machine
None
2014-06-25T23:59:59.000Z
The Dual Axis Radiographic Hydrodynamic Test (DARHT) facility at Los Alamos National Laboratory is an essential scientific tool that supports Stockpile Stewardship at the Laboratory. The World's most powerful x-ray machine, it's used to take high-speed images of mock nuclear devices - data that is used to confirm and modify advanced computer codes in assuring the safety, security, and effectiveness of the U.S. nuclear deterrent.
Stellar hydrodynamical modeling of dwarf galaxies: simulation methodology, tests, and first results
Vorobyov, Eduard I; Hensler, Gerhard
2015-01-01T23:59:59.000Z
Cosmological simulations still lack numerical resolution or physical processes to simulate dwarf galaxies in sufficient details. Accurate numerical simulations of individual dwarf galaxies are thus still in demand. We aim at (i) studying in detail the coupling between stars and gas in a galaxy, exploiting the so-called stellar hydrodynamical approach, and (ii) studying the chemo-dynamical evolution of individual galaxies starting from self-consistently calculated initial gas distributions. We present a novel chemo-dynamical code in which the dynamics of gas is computed using the usual hydrodynamics equations, while the dynamics of stars is described by the stellar hydrodynamics approach, which solves for the first three moments of the collisionless Boltzmann equation. The feedback from stellar winds and dying stars is followed in detail. In particular, a novel and detailed approach has been developed to trace the aging of various stellar populations, which enables an accurate calculation of the stellar feedba...
Jonkman, J. M.; Sclavounos, P. D.
2006-01-01T23:59:59.000Z
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.
Hydrodynamics of phase transition fronts and the speed of sound in the plasma
Leonardo Leitao; Ariel Megevand
2015-03-06T23:59:59.000Z
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
2015-01-01T23:59:59.000Z
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...
Di-jet hadron pair correlation in a hydrodynamical model with a quenching jet
A. K. Chaudhuri
2008-01-15T23:59:59.000Z
In jet quenching, a hard QCD parton, before fragmenting into a jet of hadrons, deposits a fraction of its energy in the medium, leading to suppressed production of high-$p_T$ hadrons. Assuming that the deposited energy quickly thermalizes, we simulate the subsequent hydrodynamic evolution of the QGP fluid. Hydrodynamic evolution and subsequent particle emission depend on the jet trajectories. Azimuthal distribution of excess $\\pi^-$ due to quenching jet, averaged over all the trajectories, reasonably well reproduce the di-hadron correlation as measured by the STAR and PHENIX collaboration in central and in peripheral Au+Au collisions.
Spin current evolution in the separated spin-up and spin-down quantum hydrodynamics
Trukhanova, Mariya Iv
2015-01-01T23:59:59.000Z
We have developed the quantum hydrodynamic model that describes particles with spin-up and with spin-down in separate. We have derived the equation of the spin current evolution as a part of the set of the quantum hydrodynamics (QHD) equations that treat particles with different projection of spin on the preferable direction as two different species. We have studied orthogonal propagation of waves in the external magnetic field and determined the contribution of quantum corrections due to the Bohm potential and to magnetization energy of particles with different projections of spin in the spin current wave dispersion. We have analyzed the limits of weak and strong magnetic fields.
Hydrodynamic flow in lower Cretaceous Muddy sandstone, Gas Draw Field, Powder River Basin, Wyoming
Lin, Joseph Tien-Chin
1978-01-01T23:59:59.000Z
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...
Transport Coefficients of Non-Newtonian Fluid and Causal Dissipative Hydrodynamics
T. Koide; T. Kodama
2008-10-20T23:59:59.000Z
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.
Exploring Hydrodynamic Modeling of Texas Bays With focus on Corpus Christi Bay & Lavaca Bay
Furnans, Jordan
2004-01-01T23:59:59.000Z
on the circulation and salinity patterns within the estuarine system. The model of choice is the 2- dimensional, depth averaged finite element model TxBLEND. Exploring Hydrodynamic Modeling of Texas Bays - Furnans 4 Figure 4 – TxBLEND Finite Element Grid w... of the isnull grid function in ArcGIS. Once this second grid is completed, the final bathymetry grid is created by adding the grids from step one and step two. Exploring Hydrodynamic Modeling of Texas Bays - Furnans 14 Figure 10 – Continuous...
Temperature-extrapolation method for Implicit Monte Carlo - Radiation hydrodynamics calculations
McClarren, R. G. [Department of Nuclear Engineering, Texas A and M University, 3133 TAMU, College Station, TX 77802 (United States); Urbatsch, T. J. [XTD-5: Air Force Systems, Los Alamos National Laboratory, P.O. Box 1663, Los Alamos, NM 77845 (United States)
2013-07-01T23:59:59.000Z
We present a method for implementing temperature extrapolation in Implicit Monte Carlo solutions to radiation hydrodynamics problems. The method is based on a BDF-2 type integration to estimate a change in material temperature over a time step. We present results for radiation only problems in an infinite medium and for a 2-D Cartesian hohlraum problem. Additionally, radiation hydrodynamics simulations are presented for an RZ hohlraum problem and a related 3D problem. Our results indicate that improvements in noise and general behavior are possible. We present considerations for future investigations and implementations. (authors)
Statistical Estimation of Two-Body Hydrodynamic Properties Using System Identification
Xie, Chen
2010-01-14T23:59:59.000Z
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...
Cheng, X.; Wang, Z. G.; Kobayashi, S.; Nakamoto, K.; Yamazaki, K.
2010-01-01T23:59:59.000Z
axis Wire EDM machine X. Cheng & Z. G. Wang & S. Kobayashi &Tool fabrication X. Cheng (*) : Z. G. Wang : K. Yamazaki
Chen, Shih-Chi
This paper presents the design and characterization of a three-axis thermomechanical actuator-based endoscopic scanner for obtaining ex vivo two-photon images. The scanner consisted of two sub-systems: 1) an optical system ...
Knot undulator to generate linearly polarized photons with low on-axis power density
Qiao, S; Feng, Donglai; Hussain, Z; Shen, Z -X
2008-01-01T23:59:59.000Z
Heat load on beamline optics is a serious problem to generate pure linearly polarized photons in the third generation synchrotron radiation facilities. For permanent magnet undulators, this problem can be overcome by a figure-8 operating mode. But there is still no good method to tackle this problem for electromagnetic elliptical undulators. Here, a novel operating mode is suggested, which can generate pure linearly polarized photons with very low on-axis heat load. Also the available minimum photon energy of linearly polarized photons can be extended much by this method.
Tullis, Stephen
Medium-solidity Vertical Axis Wind Turbines for use in Urban Environments S. Tullis, A. Fiedler, K Vertical axis wind turbines are currently experiencing a renewed interest in small- scale applications: vertical axis wind turbines, vibration, blade aerodynamics #12;Introduction In community wind power
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)
1994-01-01T23:59:59.000Z
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
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
Berlyand, Leonid
Viscosity of Bacterial Suspensions: Hydrodynamic Interactions and Self-Induced Noise Shawn D. Ryan, 2011) The viscosity of a suspension of swimming bacteria is investigated analytically and numerically fluid, result in a dramatic reduction of the effective viscosity. In agreement with experiments
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
Experiments on wind-perturbed rogue wave hydrodynamics using the Peregrine breather model
Boyer, Edmond
Engineering, Imperial College London, London SW7 2AZ, United Kingdom 2 Dynamics Group, Hamburg University on the surface that results in a flux of energy from the wind to the waves and (ii) it generates a rotationalExperiments on wind-perturbed rogue wave hydrodynamics using the Peregrine breather model A
Kinetic equation for a soliton gas, its hydrodynamic reductions and symmetries
Kinetic equation for a soliton gas, its hydrodynamic reductions and symmetries G.A. El1 , A 2 Institute of Spectroscopy, Russian Academy of Sciences, Troitsk, Moscow Region, Russia 3 Lebedev Physics, Urals Division of Russian Academy of Sciences, Ekaterinburg, Russia Abstract We study a new class
Hydrodynamic forces and surface topography: Centimeter-scale spatial variation in wave forces
Denny, Mark
Hydrodynamic forces and surface topography: Centimeter-scale spatial variation in wave forces. On the rugose rock surfaces of wave-swept shores, interactions between substratum topography and wave-induced flow may create such a spatially variable environment. Topography Numerous investigators have explored
Basic design and hydrodynamic analysis of three-column TLP and comparison with ISSC TLP
Sebastian, Abhilash
2000-01-01T23:59:59.000Z
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...
Effect of Second-Order Hydrodynamics on Floating Offshore Wind Turbines: Preprint
Roald, L.; Jonkman, J.; Robertson, A,; Chokani, N.
2013-07-01T23:59:59.000Z
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.
Luo, Haoxiang
An efficient immersed boundary-lattice Boltzmann method for the hydrodynamic interaction of elastic flapping in the Kármán gait and the entrainment regions near a cylinder is studied to model fish swimming in these regions. Significant drag reduction is found for the filament, and the result is consistent
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 a corkscrew within a conduit of viscously entrained fluid, whose upward recirculation braids the jet issues in all are mixing and entrainment by the jet and the nonlinear regime far beyond the instabilities
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
Hydrodynamical simulations of penetrative convection and generation of internal gravity waves
StÃªpieÃ±, Kazimierz
of hydrodynamical simulations. We measure the energy flux transported by these waves and find it compatibleÂLopez & Spruit 1991), mixing by random motions induced by the waves (Schatzman 1996), and the transport depends on the efficiency of the generation of internal gravity waves, which is linked to the dynamics
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
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
EFFECTS OF CHAMBER GEOMETRY AND GAS PROPERTIES ON HYDRODYNAMIC EVOLUTION OF IFE Zoran Dragojlovic1
Najmabadi, Farrokh
-rays and ions travel through the chamber and deposit some of their energy in the chamber background gas; the effects of various heat sources and transfer mechanisms such as photon and ion heat deposition and chamberEFFECTS OF CHAMBER GEOMETRY AND GAS PROPERTIES ON HYDRODYNAMIC EVOLUTION OF IFE CHAMBERS Zoran
Tlusty, Tsvi
Anomalous Microfluidic Phonons Induced by the Interplay of Hydrodynamic Screening the acoustic normal modes (``phonons'') of a 1D microfluidic droplet crystal at the crossover between 2D flow.55.Dÿ, 47.60.+i, 47.63.mf, 63.22.+m Microfluidic two-phase flow offers experimental tools to investigate
McArthur, Karl Edward
1996-01-01T23:59:59.000Z
, and hydraulic structures. The results of the SW=D model were compared to results from an application of the TXBLEND model by Texas Water Development Board to the same part of the estuary. TXBLEND is a two-dimensional hydrodynamic model based on the finite...
A Phase Field Crystal Model for Colloidal Suspensions with Hydrodynamic Interactions
Praetorius, Simon
2013-01-01T23:59:59.000Z
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.
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
XXII ICTAM, 2529 August 2008, Adelaide, Australia PERISTALSIS AND HYDRODYNAMIC INSTABILITIES
Hoepffner, Jérôme
in hydrodynamic instabilities. A propagating wall deformation generates pressure gradients in the flow, which act channel has its height reduced as if locally constricted by a cuff, sliding towards the right. The wall to the propagation of the constricted region, a high pressure is generated in P1 where the fluid is pushed down
Porous Superhydrophobic Membranes: Hydrodynamic Anomaly in Oscillating Flows S. Rajauria,1,2
that a stable Knudsen layer of gas percolates on the membrane, changing the boundary condition. This is be simultaneously. Oscillatory hydrodynamic measurements on porous superhydropho- bic membranes as a function of Ès Knudsen layer of air at the interface. DOI: 10.1103/PhysRevLett.107.174501 PACS numbers: 47.61.Àk, 47
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
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
Core-annular flow through a horizontal pipe: Hydrodynamic counterbalancing of buoyancy force on core
Vuik, Kees
Core-annular flow through a horizontal pipe: Hydrodynamic counterbalancing of buoyancy force of a high-viscosity liquid core surrounded by a low-viscosity liquid annular layer through a horizontal pipe through a horizontal pipe. Since the densities of the two liq- uids are almost always different, gravity
GENERIC HYDRODYNAMIC INSTABILITY OF CURL EIGENFIELDS JOHN ETNYRE AND ROBERT GHRIST
Ghrist, Robert W.
GENERIC HYDRODYNAMIC INSTABILITY OF CURL EIGENFIELDS JOHN ETNYRE AND ROBERT GHRIST ABSTRACT. We prove that for generic geometry, the curl-eigenfield solutions to the steady Euler equations on R3 /Z3 class of flows -- the curl eigenfields -- which form the most fascinating and challenging steady
Denny, Mark
A limpet shell shape that reduces drag: laboratory demonstration of a hydrodynamic mechanism shell shape that reduces drag: laboratory demonstration of a hydrodynamic mechanism and an exploration that reduces drag: laboratory demonstration of a hydrodynamic mechanism and an exploration of its effectiveness
A pulsed power hydrodynamics approach to exploring properties of warm dense matter
Reinovsky, Robert Emil [Los Alamos National Laboratory
2008-01-01T23:59:59.000Z
Pulsed Power Hydrodynamics, as an application of low-impedance, pulsed power, and high magnetic field technology developed over the last decade to study advanced hydrodynamic problems, instabilities, turbulence, and material properties, can potentially be applied to the study of the behavior and properties of warm dense matter (WDM) as well. Exploration of the properties, such as equation of state and conductivity, of warm dense matter is an emerging area of study focused on the behavior of matter at density near solid density (from 10% of solid density to a few times solid density) and modest temperatures ({approx}1-10 eV). Warm dense matter conditions can be achieved by laser or particle beam heating of very small quantities of matter on timescales short compared to the subsequent hydrodynamic expansion timescales (isochoric heating) and a vigorous community of researchers is applying these techniques using petawatt scale laser systems, but the microscopic size scale of the WDM produced in this way limits access to some physics phenomena. Pulsed power hydrodynamics techniques, either through high convergence liner compression of a large volume, modest density, low temperature plasma to densities approaching solid density or through the explosion and subsequent expansion of a conductor (wire) against a high pressure (density) gas background (isobaric expansion) techniques both offer the prospect for producing warm dense matter in macroscopic quantities. However, both techniques demand substantial energy, proper power conditioning and delivery, and an understanding of the hydrodynamic and instability processes that limit each technique. Similarly, liner compression of normal density material, perhaps using multiple reflected shocks can provide access to the challenging region above normal density -- again with the requirement of very large amounts of driving energy. In this paper we will provide an introduction to techniques that might be applied to explore this interesting new application of the energy-rich technology of pulse power and high magnetic fields.
A multichannel magnetic probe system for analysing magnetic fluctuations in helical axis plasmas
Haskey, S. R.; Blackwell, B. D.; Seiwald, B.; Hole, M. J.; Pretty, D. G.; Howard, J.; Wach, J. [Plasma Research Laboratory, Research School of Physical Sciences and Engineering, The Australian National University, Canberra, ACT 0200 (Australia)] [Plasma Research Laboratory, Research School of Physical Sciences and Engineering, The Australian National University, Canberra, ACT 0200 (Australia)
2013-09-15T23:59:59.000Z
The need to understand the structure of magnetic fluctuations in H-1NF heliac [S. Hamberger et al., Fusion Technol. 17, 123 (1990)] plasmas has motivated the installation of a sixteen former, tri-axis helical magnetic probe Mirnov array (HMA). The new array complements two existing poloidal Mirnov arrays by providing polarisation information, higher frequency response, and improved toroidal resolution. The helical placement is ideal for helical axis plasmas because it positions the array as close as possible to the plasma in regions of varying degrees of favourable curvature in the magnetohydrodynamic sense, but almost constant magnetic angle. This makes phase variation with probe position near linear, greatly simplifying the analysis of the data. Several of the issues involved in the design, installation, data analysis, and calibration of this unique array are presented including probe coil design, frequency response measurements, mode number identification, orientation calculations, and mapping probe coil positions to magnetic coordinates. Details of specially designed digitally programmable pre-amplifiers, which allow gains and filters to be changed as part of the data acquisition initialisation sequence and stored with the probe signals, are also presented. The low shear heliac geometry [R. Jiménez-Gómez et al., Nucl. Fusion 51, 033001 (2011)], flexibility of the H-1NF heliac, and wealth of information provided by the HMA create a unique opportunity for detailed study of Alfvén eigenmodes, which could be a serious issue for future fusion reactors.
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.
2014-10-28T23:59:59.000Z
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
Rempp, Hansjoerg, E-mail: hansjoerg.rempp@med.uni-tuebingen.de [Eberhard Karls University of Tuebingen, Department of Diagnostic and Interventional Radiology (Germany); Scharpf, Marcus [Insitute of Pathology, Eberhard Karls University of Tuebingen, Department of General Pathology and Pathological Anatomy (Germany); Voigtlaender, Matthias [ERBE Elektromedizin GmbH (Germany); Schraml, Christina; Schmidt, Diethard [Eberhard Karls University of Tuebingen, Department of Diagnostic and Interventional Radiology (Germany); Fend, Falko [Insitute of Pathology, Eberhard Karls University of Tuebingen, Department of General Pathology and Pathological Anatomy (Germany); Claussen, Claus D. [Eberhard Karls University of Tuebingen, Department of Diagnostic and Interventional Radiology (Germany); Enderle, Markus D. [ERBE Elektromedizin GmbH (Germany); Pereira, Philippe L. [Klinik fuer Radiologie, Minimalinvasive Therapien und Nuklearmedizin (Germany); Clasen, Stephan [Eberhard Karls University of Tuebingen, Department of Diagnostic and Interventional Radiology (Germany)
2011-02-15T23:59:59.000Z
Purpose: To evaluate the ablation zones created with a gas-cooled bipolar radiofrequency applicator performed on ex vivo bovine liver tissue. Materials and Methods: A total of 320 ablations with an internally gas-cooled bipolar radiofrequency applicator were performed on fresh ex vivo bovine liver tissue, varying the ablation time (5, 10, 15, and 20 min), power (20, 30, 40, and 50 W), and gas pressure of the CO{sub 2} used for cooling (585, 600, 615, 630, 645 psi), leading to a total of 80 different parameter combinations. Size and shape of the white coagulation zone were assessed. Results: The largest complete ablation zone was achieved after 20 min of implementing 50 W and 645 psi, resulting in a short axis of mean 46 {+-} 1 mm and a long axis of 56 {+-} 2 mm (mean {+-} standard deviation). Short-axis diameters increased between 5 and 20 min of ablation time at 585 psi (increase of the short axis was 45% at 30 W, 29% at 40 W, and 39% at 50 W). This increase was larger at 645 psi (113% at 30 W, 67% at 40 W, and 70% at 50 W). Macroscopic assessment and NADH (nicotinamide adenine dinucleotide) staining revealed incompletely ablated tissue along the needle track in 18 parameter combinations including low-power settings (20 and 30 W) and different cooling levels and ablation times. Conclusion: Gas-cooled radiofrequency applicators increase the short-axis diameter of coagulation in an ex vivo setting if appropriate parameters are selected.
Super-NOnuA: A Long-baseline neutrino experiment with two off-axis detectors
Mena Requejo, Olga; /Fermilab; Palomares-Ruiz, Sergio; /Vanderbilt U.; Pascoli, Silvia; /CERN
2005-04-01T23:59:59.000Z
Establishing the neutrino mass hierarchy is one of the fundamental questions that will have to be addressed in the next future. Its determination could be obtained with long-baseline experiments but typically suffers from degeneracies with other neutrino parameters. We consider here the NOvA experiment configuration and propose to place a second off-axis detector, with a shorter baseline, such that, by exploiting matter effects, the type of neutrino mass hierarchy could be determined with only the neutrino run. We show that the determination of this parameter is free of degeneracies, provided the ratio L/E, where L the baseline and E is the neutrino energy, is the same for both detectors.
Extended Kalman filtering applied to a two-axis robotic arm with flexible links
Lertpiriyasuwat, V.; Berg, M.C.; Buffinton, K.W.
2000-03-01T23:59:59.000Z
An industrial robot today uses measurements of its joint positions and models of its kinematics and dynamics to estimate and control its end-effector position. Substantially better end-effector position estimation and control performance would be obtainable if direct measurements of its end-effector position were also used. The subject of this paper is extended Kalman filtering for precise estimation of the position of the end-effector of a robot using, in addition to the usual measurements of the joint positions, direct measurements of the end-effector position. The estimation performances of extended Kalman filters are compared in applications to a planar two-axis robotic arm with very flexible links. The comparisons shed new light on the dependence of extended Kalman filter estimation performance on the quality of the model of the arm dynamics that the extended Kalman filter operates with.
Customized airfoils and their impact on VAWT (Vertical-Axis Wind Turbine) cost of energy
Berg, D.E.
1990-01-01T23:59:59.000Z
Sandia National Laboratories has developed a family of airfoils specifically designed for use in the equatorial portion of a Vertical-Axis Wind Turbine (VAWT) blade. An airfoil of that family has been incorporated into the rotor blades of the DOE/Sandia 34-m diameter VAWT Test Bed. The airfoil and rotor design process is reviewed. Comparisons with data recently acquired from flow visualization tests and from the DOE/Sandia 34-m diameter VAWT Test Bed illustrate the success that was achieved in the design. The economic optimization model used in the design is described and used to evaluate the effect of modifications to the current Test Bed blade. 1 tab., 11 figs., 13 refs.
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.
2015-07-01T23:59:59.000Z
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
Hydrodynamic flow in the vicinity of a nanopore induced by an applied voltage
Mao, Mao; Hu, Guohui
2013-01-01T23:59:59.000Z
Continuum simulation is employed to study ion transport and fluid flow through a nanopore in a solid-state membrane under an applied potential drop. Results show the existence of concentration polarization layers on the surfaces of the membrane. The nonuniformity of the ionic distribution gives rise to an electric pressure that drives vortical motion in the fluid. There is also a net hydrodynamic flow through the nanopore due to an asymmetry induced by the membrane surface charge. The qualitative behavior is similar to that observed in a previous study using molecular dynamic simulations. The current--voltage characteristics show some nonlinear features but are not greatly affected by the hydrodynamic flow in the parameter regime studied. In the limit of thin Debye layers, the electric resistance of the system can be characterized using an equivalent circuit with lumped parameters. Generation of vorticity can be understood qualitatively from elementary considerations of the Maxwell stresses. However, the flow...
Running faster together: huge speed up of thermal ratchets due to hydrodynamic coupling
Paolo Malgaretti; Ignacio Pagonabarraga; Daan Frenkel
2012-09-19T23:59:59.000Z
We present simulations that reveal a surprisingly large effect of hydrodynamic coupling on the speed of thermal ratchet motors. The model that we use considers particles performing thermal ratchet motion in a hydrodynamic solvent. Using particle-based, mesoscopic simulations that maintain local momentum conservation, we analyze quantitatively how the coupling to the surrounding fluid affects ratchet motion. We find that coupling can increase the mean velocity of the moving particles by almost two orders of magnitude, precisely because ratchet motion has both a diffusive and a deterministic component. The resulting coupling also leads to the formation of aggregates at longer times. The correlated motion that we describe increases the efficiency of motor-delivered cargo transport and we speculate that the mechanism that we have uncovered may play a key role in speeding up molecular motor-driven intracellular transport.
Swaddiwudhipong, S; Liu, Z S
2012-01-01T23:59:59.000Z
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...
Kinetic freeze-out, particle spectra and harmonic flow coefficients from mode-by-mode hydrodynamics
Stefan Floerchinger; Urs Achim Wiedemann
2014-08-27T23:59:59.000Z
The kinetic freeze-out for the hydrodynamical description of relativistic heavy ion collisions is discussed using a background-fluctuation splitting of the hydrodynamical fields. For a single event, the particle spectrum, or its logarithm, can be written as the sum of background part that is symmetric with respect to azimuthal rotations and longitudinal boosts and a part containing the contribution of fluctuations or deviations from the background. Using a complete orthonormal basis to characterize the initial state allows one to write the double differential harmonic flow coefficients determined by the two-particle correlation method as matrix expressions involving the initial fluid correlations. We discuss the use of these expressions for a mode-by-mode analysis of fluctuating initial conditions in heavy ion collisions.
Schaal, Kevin; Chandrashekar, Praveen; Pakmor, Rüdiger; Klingenberg, Christian; Springel, Volker
2015-01-01T23:59:59.000Z
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...
Non-Abelian hydrodynamics and the flow of spin in spin-orbit coupled substances
Leurs, B.W.A. [Instituut Lorentz for Theoretical Physics, Leiden University, Leiden (Netherlands)], E-mail: leurs@lorentz.leidenuniv.nl; Nazario, Z.; Santiago, D.I.; Zaanen, J. [Instituut Lorentz for Theoretical Physics, Leiden University, Leiden (Netherlands)
2008-04-15T23:59:59.000Z
Motivated by the heavy ion collision experiments there is much activity in studying the hydrodynamical properties of non-Abelian (quark-gluon) plasmas. A major question is how to deal with color currents. Although not widely appreciated, quite similar issues arise in condensed matter physics in the context of the transport of spins in the presence of spin-orbit coupling. The key insight is that the Pauli Hamiltonian governing the leading relativistic corrections in condensed matter systems can be rewritten in a language of SU(2) covariant derivatives where the role of the non-Abelian gauge fields is taken by the physical electromagnetic fields: the Pauli system can be viewed as Yang-Mills quantum-mechanics in a 'fixed frame', and it can be viewed as an 'analogous system' for non-Abelian transport in the same spirit as Volovik's identification of the He superfluids as analogies for quantum fields in curved space time. We take a similar perspective as Jackiw and coworkers in their recent study of non-Abelian hydrodynamics, twisting the interpretation into the 'fixed frame' context, to find out what this means for spin transport in condensed matter systems. We present an extension of Jackiw's scheme: non-Abelian hydrodynamical currents can be factored in a 'non-coherent' classical part, and a coherent part requiring macroscopic non-Abelian quantum entanglement. Hereby it becomes particularly manifest that non-Abelian fluid flow is a much richer affair than familiar hydrodynamics, and this permits us to classify the various spin transport phenomena in condensed matter physics in an unifying framework. The 'particle based hydrodynamics' of Jackiw et al. is recognized as the high temperature spin transport associated with semiconductor spintronics. In this context the absence of faithful hydrodynamics is well known, but in our formulation it is directly associated with the fact that the covariant conservation of non-Abelian currents turns into a disastrous non-conservation of the incoherent spin currents of the high temperature limit. We analyze the quantum-mechanical single particle currents of relevance to mesoscopic transport with as highlight the Ahronov-Casher effect, where we demonstrate that the intricacies of the non-Abelian transport render this effect to be much more fragile than its abelian analog, the Ahronov-Bohm effect. We subsequently focus on spin flows protected by order parameters. At present there is much interest in multiferroics where non-collinear magnetic order triggers macroscopic electric polarization via the spin-orbit coupling. We identify this to be a peculiarity of coherent non-Abelian hydrodynamics: although there is no net particle transport, the spin entanglement is transported in these magnets and the coherent spin 'super' current in turn translates into electric fields with the bonus that due to the requirement of single valuedness of the magnetic order parameter a true hydrodynamics is restored. Finally, 'fixed-frame' coherent non-Abelian transport comes to its full glory in spin-orbit coupled 'spin superfluids', and we demonstrate a new effect: the trapping of electrical line charge being a fixed frame, non-Abelian analog of the familiar magnetic flux trapping by normal superconductors. The only known physical examples of such spin superfluids are the {sup 3}He A- and B-phase where unfortunately the spin-orbit coupling is so weak that it appears impossible to observe these effects.
Energy flow between two hydrodynamically coupled particles kept at different effective temperatures
Antoine Bérut; Artyom Petrosyan; Sergio Ciliberto
2015-05-26T23:59:59.000Z
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.
The Kozai-Lidov Mechanism in Hydrodynamical Disks - II. Effects of binary and disk parameters
Fu, Wen; Martin, Rebecca G
2015-01-01T23:59:59.000Z
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)
2009-07-21T23:59:59.000Z
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)
2011-11-15T23:59:59.000Z
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 models of self-organized dynamics: derivation and existence theory
Pierre Degond; Jian-Guo Liu; Sébastien Motsch; Vladislav Panferov
2011-08-16T23:59:59.000Z
This paper is concerned with the derivation and analysis of hydrodynamic models for systems of self-propelled particles subject to alignment interaction and attraction-repulsion. The starting point is the kinetic model considered in earlier work of Degond & Motsch with the addition of an attraction-repulsion interaction potential. Introducing different scalings than in Degond & Motsch, the non-local effects of the alignment and attraction-repulsion interactions can be kept in the hydrodynamic limit and result in extra pressure, viscosity terms and capillary force. The systems are shown to be symmetrizable hyperbolic systems with viscosity terms. A local-in-time existence result is proved in the 2D case for the viscous model and in the 3D case for the inviscid model. The proof relies on the energy method.
Tung, Ryan C., E-mail: ryan.tung@nist.gov; Killgore, Jason P.; Hurley, Donna C. [National Institute of Standards and Technology, Boulder, Colorado 80305 (United States)
2014-06-14T23:59:59.000Z
We present a method to correct for surface-coupled inertial and viscous fluid loading forces in contact resonance (CR) atomic force microscopy (AFM) experiments performed in liquid. Based on analytical hydrodynamic theory, the method relies on experimental measurements of the AFM cantilever's free resonance peaks near the sample surface. The free resonance frequencies and quality factors in both air and liquid allow reconstruction of a continuous hydrodynamic function that can be used to adjust the CR data in liquid. Validation experiments utilizing thermally excited free and in-contact spectra were performed to assess the accuracy of our approach. Results show that the method recovers the air frequency values within approximately 6%. Knowledge of fluid loading forces allows current CR analysis techniques formulated for use in air and vacuum environments to be applied to liquid environments. Our technique greatly extends the range of measurement environments available to CR-AFM.
Solving 3D relativistic hydrodynamical problems with WENO discontinuous Galerkin methods
Bugner, Marcus; Bernuzzi, Sebastiano; Weyhausen, Andreas; Bruegmann, Bernd
2015-01-01T23:59:59.000Z
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.
Analysis and verification of a three-dimensional hydrodynamic numerical model
Abraham, David Daniel
1991-01-01T23:59:59.000Z
of Advisory Committee: Dr. W. P. James A three-dimensional hydrodynamic numerical model (RMA10) was analyized and verified. The verification process involved the comparison of model and measured water surface elevations, velocities, and depth averaged... velocities. The verification (measured) data were obtained from a large (200 cfs) flume. The numerical grid was set up such that the spacial location of the computational points was as close as practical to that of the measured data. The model computed...
Larberg, Gregory Martin
1976-01-01T23:59:59.000Z
stratigraphic traps in the Lower Cretaceous Muddy Sandstones on the east flank of the basin (Figure 1). The nine ? township area immediately surrounding Kitty in- cludes Kingsbury and Mill ? Gillette fields and is well ? suited for hydrodynamic study because... understanding of the relationships between pressures, flow, and the rocks themselves. 14 Nethods Subsurface data from the nine township area surround- ing Kitty field is abundant and readily available from in- dustry sources. Over 530 class "A" (analyzable...
Hydrodynamic flow in lower Cretaceous Muddy sandstone, Gas Draw Field, Powder River Basin, Wyoming
Lin, Joseph Tien-Chin
1978-01-01T23:59:59.000Z
control readily available for analysis of rock properties and fluid pressures. The nine-township area surrounding the Gas Draw field is well-suited for study of hydrodynamic effects on oil accumulation. Regional Geology Structure The citations.... Elevations for all wells were checked on topographic maps published by U. S. Geological Survey. Drill-stem tests from Gas Draw field and the surrounding nine township area are available from industry sources. About 100 repre- sentative tests were from...
A Newton-Krylov Solver for Implicit Solution of Hydrodynamics in Core Collapse Supernovae
Reynolds, D R; Swesty, F D; Woodward, C S
2008-06-12T23:59:59.000Z
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.
Gidaspow, D.
1996-04-01T23:59:59.000Z
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.
Hydrodynamic Crossovers in Surface-Directed Spinodal Decomposition and Surface Enrichment
Prabhat K. Jaiswal; Sanjay Puri; Subir K. Das
2010-11-29T23:59:59.000Z
We present comprehensive molecular dynamics (MD) results for the kinetics of surface-directed spinodal decomposition (SDSD) and surface enrichment (SE) in binary mixtures at wetting surfaces. We study the surface morphology and the growth dynamics of the wetting and enrichment layers. The growth law for the thickness of these layers shows a crossover from a diffusive regime to a hydrodynamic regime. We provide phenomenological arguments to understand this crossover.
Simulation study of the effect of hydrodynamic forces on oil recovery
Idrobo Hurtado, Eduardo Alejandro
1992-01-01T23:59:59.000Z
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...
Granular Solid Hydrodynamics (GSH): a broad-ranged macroscopic theory of granular media
Yimin Jiang; Mario Liu
2014-07-27T23:59:59.000Z
A unified continuum-mechanical theory has been until now lacking for granular media, some believe it could not exist. Derived employing the hydrodynamic approach, GSH is such a theory, though as yet a qualitative one. The behavior being accounted for includes static stress distribution, elastic wave, elasto-plastic motion, the critical state and rapid dense flow. The equations and application to a few typical experiments are presented here.
General relativistic radiation hydrodynamics of accretion flows. I: Bondi-Hoyle accretion
Olindo Zanotti; Constanze Roedig; Luciano Rezzolla; Luca Del Zanna
2015-03-10T23:59:59.000Z
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.
Development and evaluation of a coupled hydrodynamic (FVCOM) and water quality model (CE-QUAL-ICM)
Kim, Taeyun; Labiosa, Rochelle G.; Khangaonkar, Tarang; Yang, Zhaoqing; Chen, Changsheng; Qi, Jianhua; Cerco, Carl
2010-01-08T23:59:59.000Z
Recent and frequent fish-kills in waters otherwise known for their pristine high quality, created increased awareness and urgent concern regarding potential for degradation of water quality in Puget Sound through coastal eutrophication caused by increased nutrient loading. Following a detailed review of leading models and tools available in public domain, FVCOM and CE-QUAL-ICM models were selected to conduct hydrodynamic and water quality simulations for the fjordal waters of Puget Sound.
Rominger, Jeffrey T. (Jeffrey Tsaros)
2014-01-01T23:59:59.000Z
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 ...
Mosher, Phillip Andrew
1993-01-01T23:59:59.000Z
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...
Paul, Ephraim Udo
2011-02-22T23:59:59.000Z
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...
Alexeev, Boris V
2008-01-01T23:59:59.000Z
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
Paul, Ephraim Udo
2011-02-22T23:59:59.000Z
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...
Determining the neutrino mass hierarchy and CP violation in NoVA with a second off-axis detector
Mena, Olga; /Fermilab; Palomares-Ruiz, Sergio; /Vanderbilt U.; Pascoli, Silvia; /CERN /Durham U., IPPP
2005-10-01T23:59:59.000Z
We consider a Super-NOVA-like experimental configuration based on the use of two detectors in a long-baseline experiment as NOVA. We take the far detector as in the present NOVA proposal and add a second detector at a shorter baseline. The location of the second off-axis detector is chosen such that the ratio L/E is the same for both detectors, being L the baseline and E the neutrino energy. We consider liquid argon and water- Cerenkov techniques for the second off-axis detector and study, for different experimental setups, the detector mass required for the determination of the neutrino mass hierarchy, for different values of {theta}{sub 13}. We also study the capabilities of such an experimental setup for determining CP-violation in the neutrino sector. Our results show that by adding a second off-axis detector a remarkable enhancement on the capabilities of the current NOVA experiment could be achieved.
Hydrodynamic flow in the vicinity of a nanopore induced by an applied voltage
Mao Mao; Sandip Ghosal; Guohui Hu
2013-05-16T23:59:59.000Z
Continuum simulation is employed to study ion transport and fluid flow through a nanopore in a solid-state membrane under an applied potential drop. Results show the existence of concentration polarization layers on the surfaces of the membrane. The nonuniformity of the ionic distribution gives rise to an electric pressure that drives vortical motion in the fluid. There is also a net hydrodynamic flow through the nanopore due to an asymmetry induced by the membrane surface charge. The qualitative behavior is similar to that observed in a previous study using molecular dynamic simulations. The current--voltage characteristics show some nonlinear features but are not greatly affected by the hydrodynamic flow in the parameter regime studied. In the limit of thin Debye layers, the electric resistance of the system can be characterized using an equivalent circuit with lumped parameters. Generation of vorticity can be understood qualitatively from elementary considerations of the Maxwell stresses. However, the flow strength is a strongly nonlinear function of the applied field. Combination of electrophoretic and hydrodynamic effects can lead to ion selectivity in terms of valences and this could have some practical applications in separations.
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
2015-04-17T23:59:59.000Z
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
Causal hydrodynamics from kinetic theory by doublet scheme in renormalization-group method
Kyosuke Tsumura; Teiji Kunihiro
2014-09-10T23:59:59.000Z
We develop a general framework in the renormalization-group (RG) method for extracting a mesoscopic dynamics from an evolution equation by incorporating some excited (fast) modes as additional components to the invariant manifold spanned by zero modes. We call this framework the doublet scheme. We apply the doublet scheme to construct causal hydrodynamics as a mesoscopic dynamics of kinetic theory, i.e., the Boltzmann equation, in a systematic manner with no ad-hoc assumption. It is found that our equation has the same form as Grad's thirteen-moment causal hydrodynamic equation, but the microscopic formulae of the transport coefficients and relaxation times are different. In fact, in contrast to the Grad equation, our equation leads to the same expressions for the transport coefficients as given by the Chapman-Enskog expansion method and suggests novel formulae of the relaxation times expressed in terms of relaxation functions which allow a natural physical interpretation of the relaxation times. Furthermore, our theory nicely gives the explicit forms of the distribution function and the thirteen hydrodynamic variables in terms of the linearized collision operator, which in turn clearly suggest the proper ansatz forms of them to be adopted in the method of moments.
(3+1)-dimensional framework for leading-order non conformal anisotropic hydrodynamics
Leonardo Tinti
2015-05-24T23:59:59.000Z
In this work I develop a new framework for anisotropic hydrodynamics that generalizes the leading order of the hydrodynamic expansion to the full (3+1)-dimensional anisotropic massive case. Following previous works, my considerations are based on the Boltzmann kinetic equation with the collisional term treated in the relaxation time approximation. The momentum anisotropy is included explicitly in the leading term, allowing for a large difference between the longitudinal and transverse pressures as well as for non trivial transverse dynamics. Energy and momentum conservation is expressed by the first moment of the Boltzmann equation. The system of equations is closed by using the zeroth and second moments of the Boltzmann equation. The close-to-equilibrium matching with second-order viscous hydrodynamics is demonstrated. In particular, I show that the coupling between shear and bulk pressure corrections, recently proved to be important for an accurate description of momentum anisotropy and bulk viscous dynamics, does not vanish in the close-to-equilibrium limit.
Experimental and computational studies of hydrodynamics in three-phase and two-phase fluidized beds
Bahary, M.
1994-12-01T23:59:59.000Z
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
2015-01-14T23:59:59.000Z
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
2008-07-09T23:59:59.000Z
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.
Non-linear hydrodynamics of axion dark matter: relative velocity effects and "quantum forces"
Marsh, David J E
2015-01-01T23:59:59.000Z
The non-linear hydrodynamic equations for axion/scalar field dark matter (DM) in the non-relativistic Madelung-Shcr\\"{o}dinger form are derived in a simple manner, including the effects of universal expansion and Hubble drag. The hydrodynamic equations are used to investigate the relative velocity between axion DM and baryons, and the moving-background perturbation theory (MBPT) derived. Axions massive enough to be all of the DM do not affect the coherence length of the relative velocity, but the MBPT equations are modified by the inclusion of the axion effective sound speed. These MBPT equations are necessary for accurately modelling the effects of axion DM on the formation of the first cosmic structures, and suggest that the 21cm power spectrum could improve constraints on axion mass by up to four orders of magnitude with respect to the current best constraints. A further application of these results uses the "quantum force" analogy to model scalar field gradient energy in a smoothed-particle hydrodynamics ...
Yang, Zhaoqing; Liu, Hedong; Khangaonkar, Tarang P.
2006-08-03T23:59:59.000Z
The Skagit River is the largest river in the Puget Sound estuarine system. It discharges about 39% of total sediment and more than 20% of freshwater into Puget Sound. The Skagit River delta provides rich estuarine and freshwater habitats for salmon and many other wildlife species. Over the past 150 years, economic development in the Skagit River delta has resulted in significant losses of wildlife habitat, particularly due to construction of dikes. Diked portion of the delta is known as Fir Island where irrigation practices for agriculture land over the last century has resulted in land subsidence. This has also caused reduced efficiency of drainage network and impeded fish passages through the area. In this study, a three-dimensional tidal circulation model was developed for the Skagit River delta to assist estuarine restoration in the Fir Island area. The hydrodynamic model used in the study is the Finite Volume Coastal Ocean Model (FVCOM). The hydrodynamic model was calibrated using field data collected from the study area specifically for the model development. Wetting and drying processes in the estuarine delta are simulated in the hydrodynamic model. The calibrated model was applied to simulate different restoration alternatives and provide guidance for estuarine restoration and management. Specifically, the model was used to help select and design configurations that would improve the supply of sediment and freshwater to the mudflats and tidal marsh areas outside of diked regions and then improve the estuarine habitats for salmon migration.
Puget Sound Dissolved Oxygen Modeling Study: Development of an Intermediate-Scale Hydrodynamic Model
Yang, Zhaoqing; Khangaonkar, Tarang; Labiosa, Rochelle G.; Kim, Taeyun
2010-11-30T23:59:59.000Z
The Washington State Department of Ecology contracted with Pacific Northwest National Laboratory to develop an intermediate-scale hydrodynamic and water quality model to study dissolved oxygen and nutrient dynamics in Puget Sound and to help define potential Puget Sound-wide nutrient management strategies and decisions. Specifically, the project is expected to help determine 1) if current and potential future nitrogen loadings from point and non-point sources are significantly impairing water quality at a large scale and 2) what level of nutrient reductions are necessary to reduce or dominate human impacts to dissolved oxygen levels in the sensitive areas. In this study, an intermediate-scale hydrodynamic model of Puget Sound was developed to simulate the hydrodynamics of Puget Sound and the Northwest Straits for the year 2006. The model was constructed using the unstructured Finite Volume Coastal Ocean Model. The overall model grid resolution within Puget Sound in its present configuration is about 880 m. The model was driven by tides, river inflows, and meteorological forcing (wind and net heat flux) and simulated tidal circulations, temperature, and salinity distributions in Puget Sound. The model was validated against observed data of water surface elevation, velocity, temperature, and salinity at various stations within the study domain. Model validation indicated that the model simulates tidal elevations and currents in Puget Sound well and reproduces the general patterns of the temperature and salinity distributions.
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
2015-01-01T23:59:59.000Z
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...
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.
2015-06-01T23:59:59.000Z
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
The core helium flash revisited: I. One and two-dimensional hydrodynamic simulations
M. Mocak; E. Mueller; A. Weiss; K. Kifonidis
2008-05-09T23:59:59.000Z
We investigate the hydrodynamics of the core helium flash near its peak. Past research concerned with the dynamics of this event is inconclusive. However, the most recent multidimensional hydrodynamic studies suggest a quiescent behavior and seem to rule out an explosive scenario. Previous work indicated, that depending on initial conditions, employed turbulence models, grid resolution, and dimensionality of the simulation, the core helium flash leads either to the disruption of a low-mass star or to a quiescent quasi-hydrostatic evolution. We try to clarify this issue by simulating the evolution with advanced numerical methods and detailed microphysics. Assuming spherical or axial symmetry, we simulate the evolution of the helium core of a $1.25 M_{\\odot}$ star with a metallicity Z=0.02 during the core helium flash at its peak with a grid-based hydrodynamics code. We find that the core helium flash neither rips the star apart, nor that it significantly alters its structure, as convection plays a crucial role in keeping the star in hydrostatic equilibrium. In addition, our simulations show the presence of overshooting, which implies new predictions concerning mixing of chemical species in red giants.
Linn, Anne Marie
1985-01-01T23:59:59.000Z
processes. The burial history of the sandstones includes compaction of sediments and development of quartz over growths, precipitation of clays and cements, decementation, a second precipitation of clays and cements, partial dissolution of cements...) noted that the Wheat field has a tilted oil/water contact implying that hydrodynamic flow is present. The influence of hydrodynamic flow on oil entrapment was determined from the analysis of subsurface pressur es derived from drill stem tests...
LA-UR-01-4983 Recent Results of Radiation Hydrodynamics and Turbulence
Barnes, Cris W.
from a laser-heated titanium or iron foil normal to the cylinder along its axis. Use of the cylindrical pulse. The total laser energy was 19 to 20 kJ with less than 8% RMS variation in energy balance. Two
Feister, Scott; Morrison, John T; Frische, Kyle D; Orban, Chris; Ngirmang, Gregory; Handler, Abraham; Schillaci, Mark; Chowdhury, Enam A; Freeman, R R; Roquemore, W M
2015-01-01T23:59:59.000Z
Direct electron spectrum measurements show MeV energy electrons generated backward along the laser axis by a $\\lambda =$ 780 nm, 40 fs, 2.9 mJ short-pulse laser ($1.5 \\cdot 10^{18}$ W/cm$^2$). Electrons pass through a 3 mm hole in the center of the final off-axis paraboloid (OAP) and are characterized by a magnetic spectrometer. The charge collected at the OAP is hundreds of pC per pulse. A mechanism for this super-ponderomotive backward electron acceleration is discussed in the framework of 3D Particle-in-cell simulations.
Karsch,F.; Kharzeev, D.; Molnar, K.; Petreczky, P.; Teaney, D.
2008-04-21T23:59:59.000Z
The interpretation of relativistic heavy-ion collisions at RHIC energies with thermal concepts is largely based on the relative success of ideal (nondissipative) hydrodynamics. This approach can describe basic observables at RHIC, such as particle spectra and momentum anisotropies, fairly well. On the other hand, recent theoretical efforts indicate that dissipation can play a significant role. Ideally viscous hydrodynamic simulations would extract, if not only the equation of state, but also transport coefficients from RHIC data. There has been a lot of progress with solving relativistic viscous hydrodynamics. There are already large uncertainties in ideal hydrodynamics calculations, e.g., uncertainties associated with initial conditions, freezeout, and the simplified equations of state typically utilized. One of the most sensitive observables to the equation of state is the baryon momentum anisotropy, which is also affected by freezeout assumptions. Up-to-date results from lattice quantum chromodynamics on the transition temperature and equation of state with realistic quark masses are currently available. However, these have not yet been incorporated into the hydrodynamic calculations. Therefore, the RBRC workshop 'Hydrodynamics in Heavy Ion Collisions and QCD Equation of State' aimed at getting a better understanding of the theoretical frameworks for dissipation and near-equilibrium dynamics in heavy-ion collisions. The topics discussed during the workshop included techniques to solve the dynamical equations and examine the role of initial conditions and decoupling, as well as the role of the equation of state and transport coefficients in current simulations.
Field mapping by off-axis electron holography: from devices to the detection of single dopant atoms.
Dunin-Borkowski, Rafal E.
as for new innovative devices that are composed of nanowires and 2D films such as graphene. The continuous mapping, semiconductors, graphene Off-axis electron holography is a unique technique that allows be clearly resolved. Figure 2(d) shows the potential profiles of the layers compared to a HAADF intensity
-state temperatures of the irradiated receiver trusses were modelled using Strand7 FEM software. A custom written ray of these high concentrations is that off-axis reflections from the dish mirror #12;Solar2010, the 48th Au from the ideal paraboloid. 2 adjusted to allow for the difference in the lunar to solar angular
EXAMPLES OF DAMAGE DETECTION IN REAL-LIFE SETTINGS BASED ON THE POSITION OF THE NEUTRAL AXIS
Paris-Sud XI, Université de
EXAMPLES OF DAMAGE DETECTION IN REAL-LIFE SETTINGS BASED ON THE POSITION OF THE NEUTRAL AXIS discussed in this paper is to create damage detection methods based on universal parameters an appropriate parameter and validate that it can be used to detect damage in real-life settings. The centroid