Large Eddy Simulations of extinction
Ayache, S.; Garmory, A.; Tyliszczak, A.; Mastorakos, E.
2012-08-29T23:59:59.000Z
-Martinez, A. Kronenburg. Flame stabilization mechanism in lifted flames. Flow, Tur- bulence and Combustion, 87:377–406, 2011. 8. M. Mortensen, R.W. Bilger. Derivation of the conditional moment closure equations for spray combustion. Combustion and Flame, 156... .B. Devaud, R.W. Bilger. Modeling evaporation effects in conditional moment closure for spray autoignition. Combustion Theory and Modelling, 15:725–752, 2011. 13. N. Branley and W. P. Jones. Large Eddy Simulation of a Turbulent Non-premixed Flame. Combus...
Large Eddy Simulation (LES) Applied to Advanced Engine Combustion...
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Advanced Engine Combustion Research Large Eddy Simulation (LES) Applied to Advanced Engine Combustion Research 2012 DOE Hydrogen and Fuel Cells Program and Vehicle Technologies...
Large Eddy Simulation (LES) Applied to Low-Temperature and Diesel...
Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site
More Documents & Publications Large Eddy Simulation (LES) Applied to LTCDieselHydrogen Engine Combustion Research Large Eddy Simulation (LES) Applied to Advanced Engine...
Large Eddy Simulation (LES) Applied to LTC/Diesel/Hydrogen Engine...
Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site
Engine Combustion Research Large Eddy Simulation (LES) Applied to Advanced Engine Combustion Research Large Eddy Simulation (LES) Applied to LTCDieselHydrogen Engine Combustion...
Large Eddy Simulation (LES) Applied to LTC/Diesel/Hydrogen Engine...
Office of Environmental Management (EM)
Large Eddy Simulation (LES) Applied to LTCDieselHydrogen Engine Combustion Research Large Eddy Simulation (LES) Applied to LTCDieselHydrogen Engine Combustion Research 2009 DOE...
Large-Eddy Simulation of Wind-Plant Aerodynamics: Preprint
Churchfield, M. J.; Lee, S.; Moriarty, P. J.; Martinez, L. A.; Leonardi, S.; Vijayakumar, G.; Brasseur, J. G.
2012-01-01T23:59:59.000Z
In this work, we present results of a large-eddy simulation of the 48 multi-megawatt turbines composing the Lillgrund wind plant. Turbulent inflow wind is created by performing an atmospheric boundary layer precursor simulation and turbines are modeled using a rotating, variable-speed actuator line representation. The motivation for this work is that few others have done wind plant large-eddy simulations with a substantial number of turbines, and the methods for carrying out the simulations are varied. We wish to draw upon the strengths of the existing simulations and our growing atmospheric large-eddy simulation capability to create a sound methodology for performing this type of simulation. We have used the OpenFOAM CFD toolbox to create our solver.
Towards Robust Unstructured Turbomachinery Large Eddy Simulation
Watson, R. A.; Tucker, P. G.; Wang, Z.-N.; Yuan, X.
2015-06-18T23:59:59.000Z
than that of some RANS turbulence models, at hugely more expense?Figure 11. In contrast, the KEP scheme's performance was much more positive. Qual- itatively, turbulent fluctuations and the expected large scale coherent von Kar- man vortex street can... Dynamics, 3:1760? 1765, 1991. [7] A. Jameson. Formulation of kinetic energy preserving conservative schemes for gas dynamics and direct numerical simulation of one-dimensional vis- cous compressible flow in a shock tube using entropy and kinetic energy...
Adaptively refined large eddy simulations of clusters
Maier, A; Schmidt, W; Niemeyer, J C
2009-01-01T23:59:59.000Z
We present a numerical scheme for modelling unresolved turbulence in cosmological adaptive mesh refinement codes. As a first application, we study the evolution of turbulence in the intra-cluster medium and in the core of a galaxy cluster. Simulations with and without subgrid scale model are compared in detail. Since the flow in the ICM is subsonic, the global turbulent energy contribution at the unresolved length scales is smaller than 1% of the internal energy. We find that the production of turbulence is closely correlated with merger events occurring in the cluster environment, and its dissipation locally affects the cluster energy budget. Because of this additional source of dissipation, the core temperature is larger and the density is smaller in the presence of subgrid scale turbulence than in the standard adiabatic run, resulting in a higher entropy core value.
Applications of large eddy simulation methods to gyrokinetic turbulence
Bañón Navarro, A., E-mail: alejandro.banon.navarro@ipp.mpg.de; Happel, T. [Max-Planck-Institut für Plasmaphysik, EURATOM Association, D-85748 Garching (Germany)] [Max-Planck-Institut für Plasmaphysik, EURATOM Association, D-85748 Garching (Germany); Teaca, B. [Applied Mathematics Research Centre, Coventry University, Coventry CV1 5FB (United Kingdom) [Applied Mathematics Research Centre, Coventry University, Coventry CV1 5FB (United Kingdom); Max-Planck für Sonnensystemforschung, Max-Planck-Str. 2, D-37191 Katlenburg-Lindau (Germany); Max-Planck/Princeton Center for Plasma Physics (Germany); Jenko, F. [Max-Planck-Institut für Plasmaphysik, EURATOM Association, D-85748 Garching (Germany) [Max-Planck-Institut für Plasmaphysik, EURATOM Association, D-85748 Garching (Germany); Max-Planck/Princeton Center for Plasma Physics (Germany); Hammett, G. W. [Max-Planck/Princeton Center for Plasma Physics, Princeton Plasma Physics Laboratory, Princeton University, P.O. Box 451, Princeton, New Jersey 08543 (United States)] [Max-Planck/Princeton Center for Plasma Physics, Princeton Plasma Physics Laboratory, Princeton University, P.O. Box 451, Princeton, New Jersey 08543 (United States); Collaboration: ASDEX Upgrade Team
2014-03-15T23:59:59.000Z
The large eddy simulation (LES) approach—solving numerically the large scales of a turbulent system and accounting for the small-scale influence through a model—is applied to nonlinear gyrokinetic systems that are driven by a number of different microinstabilities. Comparisons between modeled, lower resolution, and higher resolution simulations are performed for an experimental measurable quantity, the electron density fluctuation spectrum. Moreover, the validation and applicability of LES is demonstrated through a series of diagnostics based on the free energetics of the system.
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.
Mesoscale and Large-Eddy Simulations for Wind Energy
Marjanovic, N
2011-02-22T23:59:59.000Z
Operational wind power forecasting, turbine micrositing, and turbine design require high-resolution simulations of atmospheric flow over complex terrain. The use of both Reynolds-Averaged Navier Stokes (RANS) and large-eddy (LES) simulations is explored for wind energy applications using the Weather Research and Forecasting (WRF) model. To adequately resolve terrain and turbulence in the atmospheric boundary layer, grid nesting is used to refine the grid from mesoscale to finer scales. This paper examines the performance of the grid nesting configuration, turbulence closures, and resolution (up to as fine as 100 m horizontal spacing) for simulations of synoptically and locally driven wind ramping events at a West Coast North American wind farm. Interestingly, little improvement is found when using higher resolution simulations or better resolved turbulence closures in comparison to observation data available for this particular site. This is true for week-long simulations as well, where finer resolution runs show only small changes in the distribution of wind speeds or turbulence intensities. It appears that the relatively simple topography of this site is adequately resolved by all model grids (even as coarse as 2.7 km) so that all resolutions are able to model the physics at similar accuracy. The accuracy of the results is shown in this paper to be more dependent on the parameterization of the land-surface characteristics such as soil moisture rather than on grid resolution.
Large-Eddy Simulation of a Turbulent Flow around a Multi-Perforated Plate
Mendez, Simon
Large-Eddy Simulation of a Turbulent Flow around a Multi-Perforated Plate Simon Mendez1 , Franck and used in Reynolds-Averaged Navier-Stokes methods cannot predict momen- tum/heat transfer on perforated plate are reported. Large-Eddy Simulations of the flow created by an infinite multi-perforated plate
Study of natural ventilation in buildings by large eddy simulation Yi Jiang and Qingyan Chen*
Chen, Qingyan "Yan"
1 Study of natural ventilation in buildings by large eddy simulation Yi Jiang and Qingyan Chen 02139 *Phone: (617) 253-7714, Fax: (617) 253-6152, Email: qchen@mit.edu Abstract Natural ventilation in the mechanical ventilation systems. Two subgrid-scale models of large eddy simulation (LES), a Smagorinsky
Large-eddy simulation of evaporating spray in a coaxial combustor
Apte, Sourabh V.
Large-eddy simulation of evaporating spray in a coaxial combustor Sourabh V. Apte a,*, Krishnan, Stanford, CA 94305, USA Abstract Large-eddy simulation of an evaporating isopropyl alcohol spray Mahesh b , Parviz Moin c a School of Mechanical, Industrial and Manufacturing Engineering, Oregon State
Large-eddy simulation of a wind turbine wake in turbulent
Firestone, Jeremy
Large-eddy simulation of a wind turbine wake in turbulent neutral shear flow Shengbai Xie, Cristina-similar velocity profile existing in the wake after a wind turbine? How does the wake influence the vertical? Motivation #12; Large-eddy simulation for turbulent flow field Actuator-line model for wind turbine ui
Groth, Clinton P. T.
Combustion by Francisco Emanuel Hernández Pérez A thesis submitted in conformity with the requirements for Large Eddy Simulation of Lean Hydrogen-Enriched Turbulent Premixed Combustion Francisco Emanuel hydrogen combustion. In recent decades, large-eddy simulation (LES) has emerged as a promising tool
XLES Part II: From Extended Large Eddy Simulation to ODTLES
Glawe, Christoph; Kerstein, Alan R; Klein, Rupert
2015-01-01T23:59:59.000Z
In turbulence research and flow applications, turbulence models like RaNS (Reynolds averaged Navier-Stokes) models and LES (Large Eddy Simulation) are used. Both models filter the governing flow equations. Thus a scale separation approach is introduced for modeling purposes with the large scales simulated using a numerical scheme while smaller scales are assumed to be less important and might be modeled more or less easily. Unfortunately small scales are frequently of big importance, e.g. in reactive flows, wall bounded flows, or flows with significant Prandtl or Schmidt number effects. Recent alternatives to these standard models are the class of models based on the one-dimensional turbulence (ODT) idea, like ODTLES. The ability of ODT to capture highly turbulent flows (recently up to $Re_\\tau = 6\\times 10^5$) allows ODTLES to realize 3D resolutions basically independent of the turbulent intensity. In two papers we provide a formal theory and application of an innovative modeling strategy for highly turbulen...
Measurements and large eddy simulation of propagating premixed flames
Masri, A.R.; Cadwallader, B.J. [School of Aerospace, Mechanical and Mechatronic Engineering, The University of Sydney, Sydney, NSW 2006 (Australia); Ibrahim, S.S. [Department of Aeronautical and Automotive Engineering, Loughborough University, Loughborough LE11 3TU (United Kingdom)
2006-07-15T23:59:59.000Z
This paper presents an experimental and numerical study of unsteady turbulent premixed flames igniting in an initially stagnant mixture and propagating past solid obstacles. The objective here is to study the outstanding issue of flow-flame interactions in transient premixed combustion environments. Particular emphasis is placed on the burning rate and the structure of the flame front. The experimental configuration consists of a chamber with a square cross-section filled with a combustible mixture of propane-air ignited from rest. An array of baffle plates as well as geometrical obstructions of varying shapes and blockage ratios, are placed in the path of the flame as it propagates from the ignition source to the vented end of the enclosure. A range of flame propagation conditions are studied experimentally. Measurements are presented for pressure-time traces, high-speed images of the flame front, mean velocities obtained from particle imaging velocimetry and laser induced fluorescence images of the hydroxyl radical OH. Three-dimensional large eddy simulations (LES) are also made for a case where a square obstacle and an array of baffle plates are placed in the chamber. The dynamic Germano model and a simple flamelet combustion model are used at the sub-grid scale. The effects of grid size and sub-grid filter width are also discussed. Calculations and measurements are found to be in good agreement with respect to flame structure and peak overpressure. Turbulence levels increase significantly at the leading edge of the flame as it propagates past the array of baffle plates and the obstacle. With reference to the regime diagrams for turbulent premixed combustion, it is noted that the flame continues to lie in the zones of thin reactions or corrugated flamelets regardless of the stage of propagation along the chamber. (author)
Helton, Donald McLean
2002-01-01T23:59:59.000Z
The premise of the work presented here is to use a common analytical tool, Computational Fluid Dynamics (CFD), along with a prevalent turbulence model, Large Eddy Simulation (LES), to study the flow past rectangular cylinders. In an attempt to use...
Evaluation of a Large Eddy Simulation's Applicability to a Worst Case Fire Scenario
DuBois, Jacqueline
The applicability of a large eddy simulation to a small scale turbulent flow problem is assessed by comparing modeled results to those recovered from a physical apparatus with the same geometry. The computational domain ...
Large-Eddy Simulation of Post-Cold-Frontal Continental Stratocumulus
Mechem, David B.; Kogan, Yefim L.; Schultz, David M.
2010-12-01T23:59:59.000Z
Previous large-eddy simulations (LES) of stratocumulus-topped boundary layers have been exclusively set in marine environments. Boundary layer stratocumulus clouds are also prevalent over the continent but have not been ...
Large-Eddy Simulation of Flow and Pollutant Transport in Urban Street Canyons with Ground Heating
Li, Xian-Xiang
Our study employed large-eddy simulation (LES) based on a one-equation subgrid-scale model to investigate the flow field and pollutant dispersion characteristics inside urban street canyons. Unstable thermal stratification ...
Nesting large-eddy simulations within mesoscale simulations for wind energy applications
Lundquist, J K; Mirocha, J D; Chow, F K; Kosovic, B; Lundquist, K A
2008-09-08T23:59:59.000Z
With increasing demand for more accurate atmospheric simulations for wind turbine micrositing, for operational wind power forecasting, and for more reliable turbine design, simulations of atmospheric flow with resolution of tens of meters or higher are required. These time-dependent large-eddy simulations (LES), which resolve individual atmospheric eddies on length scales smaller than turbine blades and account for complex terrain, are possible with a range of commercial and open-source software, including the Weather Research and Forecasting (WRF) model. In addition to 'local' sources of turbulence within an LES domain, changing weather conditions outside the domain can also affect flow, suggesting that a mesoscale model provide boundary conditions to the large-eddy simulations. Nesting a large-eddy simulation within a mesoscale model requires nuanced representations of turbulence. Our group has improved the Weather and Research Forecasting model's (WRF) LES capability by implementing the Nonlinear Backscatter and Anisotropy (NBA) subfilter stress model following Kosovic (1997) and an explicit filtering and reconstruction technique to compute the Resolvable Subfilter-Scale (RSFS) stresses (following Chow et al, 2005). We have also implemented an immersed boundary method (IBM) in WRF to accommodate complex terrain. These new models improve WRF's LES capabilities over complex terrain and in stable atmospheric conditions. We demonstrate approaches to nesting LES within a mesoscale simulation for farms of wind turbines in hilly regions. Results are sensitive to the nesting method, indicating that care must be taken to provide appropriate boundary conditions, and to allow adequate spin-up of turbulence in the LES domain.
Chen, Qingyan "Yan"
simulation Yi Jiang and Qingyan Chen* Building Technology Program Massachusetts Institute of Technology 77 direction on cross natural ventilation in building from large eddy simulation," Building and Environment, 37 in many industrial applications. To simulate natural ventilation in buildings, however, RANS modeling has
Quantifying the sensitivity of wind farm performance to array layout options using large the effects of array layout on the performance of offshore wind farms. Array layout is characterized the sensitivity of wind farm performance to array layout options using large-eddy simulation, Geophys. Res. Lett
Conjugate Heat Transfer with Large Eddy Simulation for Gas Turbine Components.
Nicoud, Franck
Conjugate Heat Transfer with Large Eddy Simulation for Gas Turbine Components. Florent Duchaine constraint for GT (gas turbines). Most existing CHT tools are developped for chained, steady phenomena. A film-cooled turbine vane is then studied. Thermal conduction in the blade implies lower wall
Numerical Investigation of a Transverse Jet in a Supersonic Crossflow using Large Eddy Simulation
Paris-Sud XI, Université de
Numerical Investigation of a Transverse Jet in a Supersonic Crossflow using Large Eddy Simulation injected fuel jets in hot supersonic crossflows. This paper describes the numerical algorithm being used into a supersonic crossflow computed on a coarse mesh. These results are discussed and similarity
Wind Energy-Related Atmospheric Boundary Layer Large-Eddy Simulation Using OpenFOAM: Preprint
Churchfield, M.J.; Vijayakumar, G.; Brasseur, J.G.; Moriarty, P.J.
2010-08-01T23:59:59.000Z
This paper develops and evaluates the performance of a large-eddy simulation (LES) solver in computing the atmospheric boundary layer (ABL) over flat terrain under a variety of stability conditions, ranging from shear driven (neutral stratification) to moderately convective (unstable stratification).
Thole, Karen A.
Elsevier Inc. All rights reserved. Keywords: Duct flow; Ribbed channels; LES 1. Introduction In an effortExperimental validation of large eddy simulations of flow and heat transfer in a stationary ribbed Abstract Accurate prediction of ribbed duct flow and heat transfer is of importance to the gas turbine
Large-Eddy Simulation of Evaporating Spray in a Coaxial Combustor
Mahesh, Krishnan
Large-Eddy Simulation of Evaporating Spray in a Coaxial Combustor Sourabh V. Apte School of Mechanical, Industrial and Manufacturing Engineering, Oregon State University, Corvallis, OR 97331 Krishnan Mahesh Department of Aerospace Engineering and Mechanics, University of Minnesota, Minneapolis, MN 55455
Large-Eddy Simulation of Evaporatively Driven Entrainment in Cloud-Topped Mixed Layers
Collett Jr., Jeffrey L.
Large-Eddy Simulation of Evaporatively Driven Entrainment in Cloud-Topped Mixed Layers TAKANOBU, Colorado (Manuscript received 1 March 2007, in final form 19 July 2007) ABSTRACT Cloud-top entrainment instability (CTEI) is a hypothesized positive feedback between cloud-top entrain- ment and enhanced turbulence
Paris-Sud XI, Université de
Computing combustion noise by combining Large Eddy Simulations with analytical models +++++ Presented by Ignacio Duran Abstract Two mechanisms control combustion noise generation as shown by Marble. A method to calculate combustion-generated noise has been implemented in a tool called CHORUS. The method
Investigation of two-fluid methods for Large Eddy Simulation of spray combustion in Gas Turbines
Investigation of two-fluid methods for Large Eddy Simulation of spray combustion in Gas Turbines the EL method well suited for gas turbine computations, but RANS with the EE approach may also be found and coupled with the LES solver of the gas phase. The equations used for each phase and the coupling terms
Massively-Parallel Spectral Element Large Eddy Simulation of a Ring-Type Gas Turbine Combustor
Camp, Joshua Lane
2012-07-16T23:59:59.000Z
The average and fluctuating components in a model ring-type gas turbine combustor are characterized using a Large Eddy Simulation at a Reynolds number of 11,000, based on the bulk velocity and the mean channel height. A spatial filter is applied...
Pitsch, Heinz
1971 Proceedings of the Combustion Institute, Volume 29, 2002/pp. 19711978 IMPROVED POLLUTANT PREDICTIONS IN LARGE-EDDY SIMULATIONS OF TURBULENT NON-PREMIXED COMBUSTION BY CONSIDERING SCALAR DISSIPATION-eddy simulation (LES) of turbulent combustion has become a subject of in- tensive research and modeling efforts
Large Eddy Simulations of Combustor Liner Flows | Argonne Leadership...
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
flow characteristics, representative of large-scale flow unsteadiness present in aircraft engines. Ultimately, the findings will be applied to an actual multi-cup General Electric...
LARGE EDDY SIMULATION OF TURBULENT BOUNDARY LAYERS OVER ROUGH BEDS
Pawlak, Geno
that determines the response of the boundary layer is not clear. One method to characterize the irregular nature with different spectral slopes using 2D 10 % loading square waves as basis functions. These square waves can) is then used to simulate the turbulent boundary layer over the rough beds. The LES solver is first validated
Examination of steam generator turbulence by large eddy simulation
Bagwell, Ted Glyn
1989-01-01T23:59:59.000Z
phenomenon in which the vortex shedding frequency is equal to the acoustic frequency. This is primarily a problem in gas heat exchangers. This work is a continuation of work started by the Electrical Power Research Institute (EPRI), wherein the LES.... The two ongoing computer simulations are in the k- c modeling (ATHOS) (EPRI 1988a; EPRI 1988e) and the LES modeling (GUST) (EPRI 1988f; EPRI 1988e; Chilukuri et al. 1987). Both of these codes have been used to calculate the flow in both the model D-4...
Broader source: Energy.gov [DOE]
Presentation given by Sandia National Laboratories at 2014 DOE Hydrogen and Fuel Cells Program and Vehicle Technologies Office Annual Merit Review and Peer Evaluation Meeting about large eddy...
Large-eddy simulations of isolated disc galaxies with thermal and turbulent feedback
Braun, Harald; Niemeyer, Jens C; Almgren, Ann S
2014-01-01T23:59:59.000Z
We present a subgrid-scale model for the Multi-phase Interstellar medium, Star formation, and Turbulence (MIST) and explore its behaviour in high-resolution large-eddy simulations of isolated disc galaxies. MIST follows the evolution of a clumpy cold and a diffuse warm component of the gas within a volume element which exchange mass and energy via various cooling, heating and mixing processes. The star formation rate is dynamically computed from the state of the gas in the cold phase. An important feature of MIST is the treatment of unresolved turbulence in the two phases and its interaction with star formation and feedback by supernovae. This makes MIST a particularly suitable model for the interstellar medium in galaxy simulations. We carried out a suite of simulations varying fundamental parameters of our feedback implementation. Several observational properties of galactic star formation are reproduced in our simulations, such as an average star formation efficiency ~1%, a typical velocity dispersion arou...
Large Eddy Simulation studies of the effects of alignment and wind farm length
Stevens, Richard J A M; Meneveau, Charles
2014-01-01T23:59:59.000Z
Large eddy simulations of wind farms are performed to study the effects of wind turbine row alignment with respect to the incoming flow direction. Various wind farms with fixed stream-wise spacing (7.85 rotor diameters) and varying lateral displacements and span-wise turbine spacings are considered, for a fixed inflow direction. Simulations show that, contrary to common belief, a perfectly staggered (checker-board) configuration does not necessarily give the highest average power output. Instead, the highest mean wind farm power output is found to depend on several factors, the most important one being the alignment that leads to minimization of wake effects from turbines in several upstream rows. This alignment typically occurs at significantly smaller angles than those corresponding to perfect staggering. The observed trends have implications for wind farm designs, especially in sites with a well-defined prevailing wind direction.
DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)
Maurer, K. D.; Bohrer, G.; Kenny, W. T.; Ivanov, V. Y.
2015-01-01T23:59:59.000Z
Surface roughness parameters, namely the roughness length and displacement height, are an integral input used to model surface fluxes. However, most models assume these parameters to be a fixed property of plant functional type and disregard the governing structural heterogeneity and dynamics. In this study, we use large-eddy simulations to explore, in silico, the effects of canopy-structure characteristics on surface roughness parameters. We performed a virtual experiment to test the sensitivity of resolved surface roughness to four axes of canopy structure: (1) leaf area index, (2) the vertical profile of leaf density, (3) canopy height, and (4) canopy gap fraction.more »We found roughness parameters to be highly variable, but uncovered positive relationships between displacement height and maximum canopy height, aerodynamic canopy height and maximum canopy height and leaf area index, and eddy-penetration depth and gap fraction. We also found negative relationships between aerodynamic canopy height and gap fraction, as well as between eddy-penetration depth and maximum canopy height and leaf area index. We generalized our model results into a virtual "biometric" parameterization that relates roughness length and displacement height to canopy height, leaf area index, and gap fraction. Using a decade of wind and canopy-structure observations in a site in Michigan, we tested the effectiveness of our model-driven biometric parameterization approach in predicting the friction velocity over heterogeneous and disturbed canopies. We compared the accuracy of these predictions with the friction-velocity predictions obtained from the common simple approximation related to canopy height, the values calculated with large-eddy simulations of the explicit canopy structure as measured by airborne and ground-based lidar, two other parameterization approaches that utilize varying canopy-structure inputs, and the annual and decadal means of the surface roughness parameters at the site from meteorological observations. We found that the classical representation of constant roughness parameters (in space and time) as a fraction of canopy height performed relatively well. Nonetheless, of the approaches we tested, most of the empirical approaches that incorporate seasonal and interannual variation of roughness length and displacement height as a function of the dynamics of canopy structure produced more precise and less biased estimates for friction velocity than models with temporally invariable parameters.« less
Temporal structure of aggregate power fluctuations in large-eddy simulations of extended wind-farms
Stevens, Richard J A M
2014-01-01T23:59:59.000Z
Fluctuations represent a major challenge for the incorporation of electric power from large wind-farms into power grids. Wind farm power output fluctuates strongly in time, over various time scales. Understanding these fluctuations, especially their spatio-temporal characteristics, is particularly important for the design of backup power systems that must be readily available in conjunction with wind-farms. In this work we analyze the power fluctuations associated with the wind-input variability at scales between minutes to several hours, using large eddy simulations (LES) of extended wind-parks, interacting with the atmospheric boundary layer. LES studies enable careful control of parameters and availability of wind-velocities simultaneously across the entire wind-farm. The present study focuses on neutral atmospheric conditions and flat terrain, using actuator-disk representations of the individual wind-turbines. We consider power from various aggregates of wind-turbines such as the total average power sign...
Large-Eddy Simulations of Zero-Net-Mass-Flux Jet Based Separation Control in a Canonical Separated
Mittal, Rajat
Large-Eddy Simulations of Zero-Net-Mass-Flux Jet Based Separation Control in a Canonical Separated by Mittal et al1 for investigating active separation control using zero-net-mass-flux jets. Large. Zero-net-mass-flux forcing of the separated flow at the superharmonics of this baseline lock
Chen, Qingyan "Yan"
1 Using Large Eddy Simulation to Study Airflows in and around Buildings Yi Jiang, Ph.D. Mingde Su-scale models of large eddy simulation (LES) to study airflows in and around buildings. They are the Smagorinsky, studies of airflow around a building often use wind tunnels that could simulate wind conditions. Notable
Creech, Angus; Maguire, A Eoghan
2014-01-01T23:59:59.000Z
We present here a computational fluid dynamics (CFD) simulation of Lillgrund offshore wind farm, which is located in the {\\O}resund Strait between Sweden and Denmark. The simulation combines a dynamic representation of wind turbines embedded within a Large-Eddy Simulation CFD solver, and uses hr-adaptive meshing to increase or decrease mesh resolution where required. This allows the resolution of both large scale flow structures around the wind farm, and local flow conditions at individual turbines; consequently, the response of each turbine to local conditions can be modelled, as well as the resulting evolution of the turbine wakes. This paper provides a detailed description of the turbine model which simulates interactions between the wind, turbine rotors, and turbine generators by calculating the forces on the rotor, the body forces on the air, and instantaneous power output. This model was used to investigate a selection of key wind speeds and directions, investigating cases where a row of turbines would ...
Stevens, Richard J A M; Meneveau, Charles
2014-01-01T23:59:59.000Z
In order to enable simulations of developing wind turbine array boundary layers with highly realistic inflow conditions a concurrent precursor method for Large Eddy Simulations is proposed. In this method we consider two domains simultaneously, i.e. in one domain a turbulent Atmospheric Boundary Layer (ABL) without wind turbines is simulated in order to generate the turbulent inflow conditions for a second domain in which the wind turbines are placed. The benefit of this approach is that a) it avoids the need for large databases in which the turbulent inflow conditions are stored and the correspondingly slow I/O operations and b) we are sure that the simulations are not negatively affected by statically swept fixed inflow fields or synthetic fields lacking the proper ABL coherent structures. Sample applications are presented, in which, in agreement with field data a strong decrease of the power output of downstream wind-turbines with respect to the first row of wind-turbines is observed for perfectly aligned ...
Sen, Baris Ali; Menon, Suresh [School of Aerospace Engineering, Georgia Institute of Technology, 270 Ferst Drive, Atlanta, GA 30332-0150 (United States); Hawkes, Evatt R. [School of Photovoltaic and Renewable Energy Engineering, The University of New South Wales, NSW 2052 (Australia); School of Mechanical and Manufacturing Engineering, The University of New South Wales, NSW 2052 (Australia)
2010-03-15T23:59:59.000Z
Large eddy simulation (LES) of a non-premixed, temporally evolving, syngas/air flame is performed with special emphasis on speeding-up the sub-grid chemistry computations using an artificial neural networks (ANN) approach. The numerical setup for the LES is identical to a previous direct numerical simulation (DNS) study, which reported considerable local extinction and reignition physics, and hence, offers a challenging test case. The chemical kinetics modeling with ANN is based on a recent approach, and replaces the stiff ODE solver (DI) to predict the species reaction rates in the subgrid linear eddy mixing (LEM) model based LES (LEMLES). In order to provide a comprehensive evaluation of the current approach, additional information on conditional statistics of some of the key species and temperature are extracted from the previous DNS study and are compared with the LEMLES using ANN (ANN-LEMLES, hereafter). The results show that the current approach can detect the correct extinction and reignition physics with reasonable accuracy compared to the DNS. The syngas flame structure and the scalar dissipation rate statistics obtained by the current ANN-LEMLES are provided to further probe the flame physics. It is observed that, in contrast to H{sub 2}, CO exhibits a smooth variation within the region enclosed by the stoichiometric mixture fraction. The probability density functions (PDFs) of the scalar dissipation rates calculated based on the mixture fraction and CO demonstrate that the mean value of the PDF is insensitive to extinction and reignition. However, this is not the case for the scalar dissipation rate calculated by the OH mass fraction. Overall, ANN provides considerable computational speed-up and memory saving compared to DI, and can be used to investigate turbulent flames in a computationally affordable manner. (author)
Congrs Franais de Mcanique Grenoble, 27-31 aot 2007 Large Eddy Simulation and experimentation in an
Paris-Sud XI, Université de
between the rotor and the stator have been attributed to the effects of the radial convective transport France Abstract: Comparisons between Large Eddy Simulation (LES) and velocity measurements have been mesures de vitesse par anémométrie laser Doppler à deux composantes. Le code LES est basé sur une méthode
Yang, Jianming
of fluid structure interaction problems. The fluid flow equations are solved on a fixed grid that does is strongly coupled to the fluid using a predictor-corrector approach. Preliminary results for both laminar and turbulent flow problems are included. Keywords: fluid/structure interaction, large-eddy simulation, sharp
A hybrid stochastic-deconvolution model for large-eddy simulation of particle-laden flow
Micha?ek, W. R., E-mail: w.michalek@tue.nl [Department of Mechanical Engineering, Eindhoven University of Technology, 5600 MB Eindhoven (Netherlands); Kuerten, J. G. M. [Department of Mechanical Engineering, Eindhoven University of Technology, 5600 MB Eindhoven (Netherlands) [Department of Mechanical Engineering, Eindhoven University of Technology, 5600 MB Eindhoven (Netherlands); Faculty EEMCS, University of Twente, 7500 AE Enschede (Netherlands); Zeegers, J. C. H.; Liew, R. [Department of Applied Physics, Eindhoven University of Technology, 5600 MB Eindhoven (Netherlands)] [Department of Applied Physics, Eindhoven University of Technology, 5600 MB Eindhoven (Netherlands); Pozorski, J. [Institute of Fluid-Flow Machinery, Polish Academy of Sciences, Gdansk (Poland)] [Institute of Fluid-Flow Machinery, Polish Academy of Sciences, Gdansk (Poland); Geurts, B. J. [Faculty EEMCS, University of Twente, 7500 AE Enschede (Netherlands) [Faculty EEMCS, University of Twente, 7500 AE Enschede (Netherlands); Department of Applied Physics, Eindhoven University of Technology, 5600 MB Eindhoven (Netherlands)
2013-12-15T23:59:59.000Z
We develop a hybrid model for large-eddy simulation of particle-laden turbulent flow, which is a combination of the approximate deconvolution model for the resolved scales and a stochastic model for the sub-grid scales. The stochastic model incorporates a priori results of direct numerical simulation of turbulent channel flow, which showed that the parameters in the stochastic model are quite independent of Reynolds and Stokes number. In order to correctly predict the flux of particles towards the walls an extra term should be included in the stochastic model, which corresponds to the term related to the well-mixed condition in Langevin models for particle dispersion in inhomogeneous turbulent flow. The model predictions are compared with results of direct numerical simulation of channel flow at a frictional Reynolds number of 950. The inclusion of the stochastic forcing is shown to yield a significant improvement over the approximate deconvolution model for the particles alone when combined with a Stokes dependent weight-factor for the well-mixed term.
Large-eddy simulations of turbulent flow for grid-to-rod fretting in nuclear reactors
Bakosi, J; Lowrie, R B; Pritchett-Sheats, L A; Nourgaliev, R R
2013-01-01T23:59:59.000Z
The grid-to-rod fretting (GTRF) problem in pressurized water reactors is a flow-induced vibration problem that results in wear and failure of the fuel rods in nuclear assemblies. In order to understand the fluid dynamics of GTRF and to build an archival database of turbulence statistics for various configurations, implicit large-eddy simulations of time-dependent single-phase turbulent flow have been performed in 3x3 and 5x5 rod bundles with a single grid spacer. To assess the computational mesh and resolution requirements, a method for quantitative assessment of unstructured meshes with no-slip walls is described. The calculations have been carried out using Hydra-TH, a thermal-hydraulics code developed at Los Alamos for the Consortium for Advanced Simulation of Light water reactors, a United States Department of Energy Innovation Hub. Hydra-TH uses a second-order implicit incremental projection method to solve the single-phase incompressible Navier-Stokes equations. The simulations explicitly resolve the la...
Large-eddy simulation of turbulent cavitating flow in a micro channel
Egerer, Christian P., E-mail: christian.egerer@aer.mw.tum.de; Hickel, Stefan; Schmidt, Steffen J.; Adams, Nikolaus A. [Institute of Aerodynamics and Fluid Mechanics, Technische Universität München, Boltzmannstr. 15, 85748 Garching bei München (Germany)
2014-08-15T23:59:59.000Z
Large-eddy simulations (LES) of cavitating flow of a Diesel-fuel-like fluid in a generic throttle geometry are presented. Two-phase regions are modeled by a parameter-free thermodynamic equilibrium mixture model, and compressibility of the liquid and the liquid-vapor mixture is taken into account. The Adaptive Local Deconvolution Method (ALDM), adapted for cavitating flows, is employed for discretizing the convective terms of the Navier-Stokes equations for the homogeneous mixture. ALDM is a finite-volume-based implicit LES approach that merges physically motivated turbulence modeling and numerical discretization. Validation of the numerical method is performed for a cavitating turbulent mixing layer. Comparisons with experimental data of the throttle flow at two different operating conditions are presented. The LES with the employed cavitation modeling predicts relevant flow and cavitation features accurately within the uncertainty range of the experiment. The turbulence structure of the flow is further analyzed with an emphasis on the interaction between cavitation and coherent motion, and on the statistically averaged-flow evolution.
DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)
Maurer, K. D.; Bohrer, G.; Ivanov, V. Y.
2014-11-27T23:59:59.000Z
Surface roughness parameters are at the core of every model representation of the coupling and interactions between land-surface and atmosphere, and are used in every model of surface fluxes. However, most models assume these parameters to be a fixed property of plant functional type and do not vary them in response to spatial or temporal changes to canopy structure. In part, this is due to the difficulty of reducing the complexity of canopy structure and its spatiotemporal dynamic and heterogeneity to less than a handful of parameters describing its effects of atmosphere–surface interactions. In this study we use large-eddy simulationsmore »to explore, in silico, the effects of canopy structure characteristics on surface roughness parameters. We performed a virtual experiment to test the sensitivity of resolved surface roughness to four axes of canopy structure: (1) leaf area index, (2) the vertical profile of leaf density, (3) canopy height, and (4) canopy gap fraction. We found roughness parameters to be highly variable, but were able to find positive relationships between displacement height and maximum canopy height, aerodynamic canopy height and maximum canopy height and leaf area index, and eddy-penetration depth and gap fraction. We also found negative relationships between aerodynamic canopy height and gap fraction, and between eddy-penetration depth and maximum canopy height and leaf area index. Using a decade of wind and canopy structure observations in a site in Michigan, we tested the effectiveness of our model-resolved parameters in predicting the frictional velocity over heterogeneous and disturbed canopies. We compared it with three other semi-empirical models and with a decade of meteorological observations. We found that parameterizations with fixed representations of roughness performed relatively well. Nonetheless, some empirical approaches that incorporate seasonal and inter-annual changes to the canopy structure performed even better than models with temporally fixed parameters.« less
Chen, Qingyan "Yan"
save energy consumed by the heating, ventilating, and air- conditioning systems in a building1 Natural Ventilation in Buildings: Measurement in a Wind Tunnel and Numerical Simulation@purdue.edu Abstract Natural ventilation in buildings can create a comfortable and healthy indoor environment, and can
Massively-Parallel Spectral Element Large Eddy Simulation of a Ring-Type Gas Turbine Combustor
Camp, Joshua Lane
2012-07-16T23:59:59.000Z
Work Output of the Turbine Filter Width Sij Strain Rate Tensor on Filtered Velocity th Thermal E ciency, First Law E ciency Kinematic Viscosity t Eddy Viscosity HPFt High Pass Filter Eddy Viscosity vii Density ij Sub Grid Stress Tensor.... Compressor . . . . . . . . . . . . . . . . . . . . . . . . 5 2. Combustor . . . . . . . . . . . . . . . . . . . . . . . . 7 3. Turbine . . . . . . . . . . . . . . . . . . . . . . . . . . 10 4. Cycle E ciency . . . . . . . . . . . . . . . . . . . . . 12 B...
A framework for the evaluation of turbulence closures used in mesoscale ocean large-eddy simulations
Graham, Jonathan Pietarila
2012-01-01T23:59:59.000Z
We present a methodology to determine the best turbulence closure for an eddy-permitting ocean model: measurement of the error-landscape of the closure's subgrid spectral transfers and flux. Using a high-resolution benchmark, we compare each closure's model of energy and enstrophy transfer to the actual transfer observed in the benchmark run. The error-landscape norms enable us to both make objective comparisons between the closures and to optimize each closure's free parameter for a fair comparison. We apply this method to 6 different closures for forced-dissipative simulations of the barotropic vorticity equation on a f-plane (2D Navier-Stokes equation). The hyper-viscous closure most closely reproduces the enstrophy cascade especially at larger scales due to the concentration of its dissipative effects to the very smallest scales. The viscous and Leith closures perform nearly as well especially at smaller scales where all three models were dissipative. The Smagorinsky closure dissipates enstrophy at the wr...
the effects of array layout on the performance of offshore wind farms. Array layout is characterized on peri- odic boundary conditions. This code, named Simulator for Offshore/Onshore Wind Farm ApplicationsQuantifying the sensitivity of wind farm performance to array layout options using large
Turbulence prediction in two- and three-dimensional bundle flows using Large Eddy Simulation
Ibrahim, Wael Abdul-Hamid
1994-01-01T23:59:59.000Z
of velocity fluctuations, small but macroscopic 'lumps' of fluid (eddies) are thrown about in the flow. Because these lumps carry mass, momentum, and energy, this enhanced mixing can lead to serious problems, such as in the increase of pressure drop in pipe...
Visualization and analysis of eddies in a global ocean simulation
Williams, Sean J [Los Alamos National Laboratory; Hecht, Matthew W [Los Alamos National Laboratory; Petersen, Mark [Los Alamos National Laboratory; Strelitz, Richard [Los Alamos National Laboratory; Maltrud, Mathew E [Los Alamos National Laboratory; Ahrens, James P [Los Alamos National Laboratory; Hlawitschka, Mario [UC DAVIS; Hamann, Bernd [UC DAVIS
2010-10-15T23:59:59.000Z
Eddies at a scale of approximately one hundred kilometers have been shown to be surprisingly important to understanding large-scale transport of heat and nutrients in the ocean. Due to difficulties in observing the ocean directly, the behavior of eddies below the surface is not very well understood. To fill this gap, we employ a high-resolution simulation of the ocean developed at Los Alamos National Laboratory. Using large-scale parallel visualization and analysis tools, we produce three-dimensional images of ocean eddies, and also generate a census of eddy distribution and shape averaged over multiple simulation time steps, resulting in a world map of eddy characteristics. As expected from observational studies, our census reveals a higher concentration of eddies at the mid-latitudes than the equator. Our analysis further shows that mid-latitude eddies are thicker, within a range of 1000-2000m, while equatorial eddies are less than 100m thick.
Churchfield, M. J.; Michalakes, J.; Vanderwende, B.; Lee, S.; Sprague, M. A.; Lundquist, J. K.; Moriarty, P. J.
2013-10-01T23:59:59.000Z
Wind plant aerodynamics are directly affected by the microscale weather, which is directly influenced by the mesoscale weather. Microscale weather refers to processes that occur within the atmospheric boundary layer with the largest scales being a few hundred meters to a few kilometers depending on the atmospheric stability of the boundary layer. Mesoscale weather refers to large weather patterns, such as weather fronts, with the largest scales being hundreds of kilometers wide. Sometimes microscale simulations that capture mesoscale-driven variations (changes in wind speed and direction over time or across the spatial extent of a wind plant) are important in wind plant analysis. In this paper, we present our preliminary work in coupling a mesoscale weather model with a microscale atmospheric large-eddy simulation model. The coupling is one-way beginning with the weather model and ending with a computational fluid dynamics solver using the weather model in coarse large-eddy simulation mode as an intermediary. We simulate one hour of daytime moderately convective microscale development driven by the mesoscale data, which are applied as initial and boundary conditions to the microscale domain, at a site in Iowa. We analyze the time and distance necessary for the smallest resolvable microscales to develop.
Churchfield, M. J.; Li, Y.; Moriarty, P. J.
2011-07-01T23:59:59.000Z
This paper presents our initial work in performing large-eddy simulations of tidal turbine array flows. First, a horizontally-periodic precursor simulation is performed to create turbulent flow data. Then that data is used to determine the inflow into a tidal turbine array two rows deep and infinitely wide. The turbines are modeled using rotating actuator lines, and the finite-volume method is used to solve the governing equations. In studying the wakes created by the turbines, we observed that the vertical shear of the inflow combined with wake rotation causes lateral wake asymmetry. Also, various turbine configurations are simulated, and the total power production relative to isolated turbines is examined. Staggering consecutive rows of turbines in the simulated configurations allows the greatest efficiency using the least downstream row spacing. Counter-rotating consecutive downstream turbines in a non-staggered array shows a small benefit. This work has identified areas for improvement, such as the use of a larger precursor domain to better capture elongated turbulent structures, the inclusion of salinity and temperature equations to account for density stratification and its effect on turbulence, improved wall shear stress modeling, and the examination of more array configurations.
Churchfield, M. J.; Li, Y.; Moriarty, P. J.
2012-07-01T23:59:59.000Z
This paper presents our initial work in performing large-eddy simulations of tidal turbine array flows. First, a horizontally-periodic precursor simulation is performed to create turbulent flow data. Then that data is used as inflow into a tidal turbine array two rows deep and infinitely wide. The turbines are modeled using rotating actuator lines, and the finite-volume method is used to solve the governing equations. In studying the wakes created by the turbines, we observed that the vertical shear of the inflow combined with wake rotation causes lateral wake asymmetry. Also, various turbine configurations are simulated, and the total power production relative to isolated turbines is examined. Staggering consecutive rows of turbines in the simulated configurations allows the greatest efficiency using the least downstream row spacing. Counter-rotating consecutive downstream turbines in a non-staggered array shows a small benefit. This work has identified areas for improvement, such as the use of a larger precursor domain to better capture elongated turbulent structures, the inclusion of salinity and temperature equations to account for density stratification and its effect on turbulence, improved wall shear stress modelling, and the examination of more array configurations.
Attinger, Daniel
in e.g. nuclear power plants. In the present work, the mixing of a hot and a cold fluid streamLarge-eddy simulations of structure effects of an upstream elbow main pipe on hot and cold fluids Fuel Injection Equipment Stock Co., Ltd., Beijing 100166, China c Department of Mechanical Engineering
Large Eddy Simulation Analysis of Flow Field Inside a High-g Combustor
Raman, Venkat
-based combustion systems. Simulation results show that mixing of fuel and oxidizer is based on a jet-in-crossflow the jet and the crossflow determine fuel penetration, and will determine combustion e ciency. Simulation
Yue, Qing; Kahn, Brian; Xiao, Heng; Schreier, Mathias; Fetzer, E. J.; Teixeira, J.; Suselj, Kay
2013-08-16T23:59:59.000Z
Cloud top entrainment instability (CTEI) is a hypothesized positive feedback between entrainment mixing and evaporative cooling near the cloud top. Previous theoretical and numerical modeling studies have shown that the persistence or breakup of marine boundary layer (MBL) clouds may be sensitive to the CTEI parameter. Collocated thermodynamic profile and cloud observations obtained from the Atmospheric Infrared Sounder (AIRS) and Moderate Resolution Imaging Spectroradiometer (MODIS) instruments are used to quantify the relationship between the CTEI parameter and the cloud-topped MBL transition from stratocumulus to trade cumulus in the northeastern Pacific Ocean. Results derived from AIRS and MODIS are compared with numerical results from the UCLA large eddy simulation (LES) model for both well-mixed and decoupled MBLs. The satellite and model results both demonstrate a clear correlation between the CTEI parameter and MBL cloud fraction. Despite fundamental differences between LES steady state results and the instantaneous snapshot type of observations from satellites, significant correlations for both the instantaneous pixel-scale observations and the long-term averaged spatial patterns between the CTEI parameter and MBL cloud fraction are found from the satellite observations and are consistent with LES results. This suggests the potential of using AIRS and MODIS to quantify global and temporal characteristics of the cloud-topped MBL transition.
Large-Eddy Simulation of Swirling Turbulent Jet Flows in Absence of Vortex Breakdown
Heinz, Stefan
simulation method to studies of the mechanism of swirl effects shows the following. Swirl breaks apart, n i 2 N0; 1 = kinematic viscosity T = Reynolds-averaged NavierStokes turbulent viscosity
Paris-Sud XI, Université de
the temperature and pressure levels reached in the combustor, and therefore the engine efficiency. Numerical simulations of the thermal interaction between fluid flows and solids offer new design paths to diminish converge to steady thermal states. There are two basic approaches to solve Conjugate Heat Transfer (CHT
Complex Effects in Large Eddy Simulation Limassol, September 20-24,2005
SIMULATIONS OF MULTIBURNER CONFIGURATIONS IN INDUSTRIAL GAS TURBINES G. Staffelbach , L. Y. M. Gicquel and T. A single burner periodic sector and a triple burner sector of an annular combustion chamber of a gas generation, gas turbines have gained an increasing role over the years. New emission regulations and growing
Large eddy simulation of supersonic combustion with application to scramjet engines
Cocks, Peter
2011-07-12T23:59:59.000Z
.38 Turbulence energy spectrum for coarse mesh using x-velocity (green), y-velocity (blue) and z-velocity (red). . . . . . . . . . . . . . . . . 176 6.39 Showing influence of cell volume scaling on turbulence initialisation with volume multiplication (left... energy spectrum, with energy E and frequency k. . . . . . 10 2.2 One dimensional energy spectra for different experimental cases, showing problem dependent large scales and universal small scales [24...
Churchfield, M. J.; Moriarty, P. J.; Hao, Y.; Lackner, M. A.; Barthelmie, R.; Lundquist, J.; Oxley, G. S.
2014-12-01T23:59:59.000Z
The focus of this work is the comparison of the dynamic wake meandering model and large-eddy simulation with field data from the Egmond aan Zee offshore wind plant composed of 36 3-MW turbines. The field data includes meteorological mast measurements, SCADA information from all turbines, and strain-gauge data from two turbines. The dynamic wake meandering model and large-eddy simulation are means of computing unsteady wind plant aerodynamics, including the important unsteady meandering of wakes as they convect downstream and interact with other turbines and wakes. Both of these models are coupled to a turbine model such that power and mechanical loads of each turbine in the wind plant are computed. We are interested in how accurately different types of waking (e.g., direct versus partial waking), can be modeled, and how background turbulence level affects these loads. We show that both the dynamic wake meandering model and large-eddy simulation appear to underpredict power and overpredict fatigue loads because of wake effects, but it is unclear that they are really in error. This discrepancy may be caused by wind-direction uncertainty in the field data, which tends to make wake effects appear less pronounced.
Sliding Interfaces for Eddy Current Simulations
Hiptmair, Ralf
Sliding Interfaces for Eddy Current Simulations Raffael Casagrande Master Thesis Supervisor: Prof. Dr. Ralf Hiptmair ZÃ¼rich, April 2013 #12;Contents Contents i 1. Introduction 1 2. Eddy Current-formulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 2.4. The eddy current problem in a moving, solid body . . . . . . . . . . . . . 9 3. Discontinuous
Singer, M; Mirocha, J; Lundquist, J; Cleve, J
2010-03-03T23:59:59.000Z
Flow dynamics in large wind projects are influenced by the turbines located within. The turbine wakes, regions characterized by lower wind speeds and higher levels of turbulence than the surrounding free stream flow, can extend several rotor diameters downstream, and may meander and widen with increasing distance from the turbine. Turbine wakes can also reduce the power generated by downstream turbines and accelerate fatigue and damage to turbine components. An improved understanding of wake formation and transport within wind parks is essential for maximizing power output and increasing turbine lifespan. Moreover, the influence of wakes from large wind projects on neighboring wind farms, agricultural activities, and local climate are all areas of concern that can likewise be addressed by wake modeling. This work describes the formulation and application of an actuator disk model for studying flow dynamics of both individual turbines and arrays of turbines within wind projects. The actuator disk model is implemented in the Weather Research and Forecasting (WRF) model, which is an open-source atmospheric simulation code applicable to a wide range of scales, from mesoscale to large-eddy simulation. Preliminary results demonstrate the applicability of the actuator disk model within WRF to a moderately high-resolution large-eddy simulation study of a small array of turbines.
Smith, P.J.; Eddings, E.G.; Ring, T.; Thornock, J.; Draper, T.; Isaac, B.; Rezeai, D.; Toth, P.; Wu, Y.; Kelly, K.
2014-08-01T23:59:59.000Z
The objective of this task is to produce predictive capability with quantified uncertainty bounds for the heat flux in commercial-scale, tangentially fired, oxy-coal boilers. Validation data came from the Alstom Boiler Simulation Facility (BSF) for tangentially fired, oxy-coal operation. This task brings together experimental data collected under Alstom’s DOE project for measuring oxy-firing performance parameters in the BSF with this University of Utah project for large eddy simulation (LES) and validation/uncertainty quantification (V/UQ). The Utah work includes V/UQ with measurements in the single-burner facility where advanced strategies for O2 injection can be more easily controlled and data more easily obtained. Highlights of the work include: • Simulations of Alstom’s 15 megawatt (MW) BSF, exploring the uncertainty in thermal boundary conditions. A V/UQ analysis showed consistency between experimental results and simulation results, identifying uncertainty bounds on the quantities of interest for this system (Subtask 9.1) • A simulation study of the University of Utah’s oxy-fuel combustor (OFC) focused on heat flux (Subtask 9.2). A V/UQ analysis was used to show consistency between experimental and simulation results. • Measurement of heat flux and temperature with new optical diagnostic techniques and comparison with conventional measurements (Subtask 9.3). Various optical diagnostics systems were created to provide experimental data to the simulation team. The final configuration utilized a mid-wave infrared (MWIR) camera to measure heat flux and temperature, which was synchronized with a high-speed, visible camera to utilize two-color pyrometry to measure temperature and soot concentration. • Collection of heat flux and temperature measurements in the University of Utah’s OFC for use is subtasks 9.2 and 9.3 (Subtask 9.4). Several replicates were carried to better assess the experimental error. Experiments were specifically designed for the generation of high-fidelity data from a turbulent oxy-coal flame for the validation of oxy-coal simulation models. Experiments were also conducted on the OFC to determine heat flux profiles using advanced strategies for O2 injection. This is important when considering retrofit of advanced O2 injection in retrofit configurations.
Draxl, C.; Churchfield, M.; Mirocha, J.; Lee, S.; Lundquist, J.; Michalakes, J.; Moriarty, P.; Purkayastha, A.; Sprague, M.; Vanderwende, B.
2014-06-01T23:59:59.000Z
Wind plant aerodynamics are influenced by a combination of microscale and mesoscale phenomena. Incorporating mesoscale atmospheric forcing (e.g., diurnal cycles and frontal passages) into wind plant simulations can lead to a more accurate representation of microscale flows, aerodynamics, and wind turbine/plant performance. Our goal is to couple a numerical weather prediction model that can represent mesoscale flow [specifically the Weather Research and Forecasting model] with a microscale LES model (OpenFOAM) that can predict microscale turbulence and wake losses.
DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)
Endo, Satoshi; Fridlind, Ann M.; Lin, Wuyin; Vogelmann, Andrew M.; Toto, Tami; Ackerman, Andrew S.; McFarquhar, Greg M.; Jackson, Robert C.; Jonsson, Haflidi H.; Liu, Yangang
2015-06-19T23:59:59.000Z
A 60-hour case study of continental boundary layer cumulus clouds is examined using two large-eddy simulation (LES) models. The case is based on observations obtained during the RACORO Campaign (Routine Atmospheric Radiation Measurement [ARM] Aerial Facility [AAF] Clouds with Low Optical Water Depths [CLOWD] Optical Radiative Observations) at the ARM Climate Research Facility's Southern Great Plains site. The LES models are driven by continuous large-scale and surface forcings, and are constrained by multi-modal and temporally varying aerosol number size distribution profiles derived from aircraft observations. We compare simulated cloud macrophysical and microphysical properties with ground-based remote sensing and aircraft observations.more »The LES simulations capture the observed transitions of the evolving cumulus-topped boundary layers during the three daytime periods, and generally reproduce variations of droplet number concentration with liquid water content (LWC), corresponding to the gradient between the cloud centers and cloud edges at given heights. The observed LWC values fall within the range of simulated values; the observed droplet number concentrations are commonly higher than simulated, but differences remain on par with potential estimation errors in the aircraft measurements. Sensitivity studies examine the influences of bin microphysics versus bulk microphysics, aerosol advection, supersaturation treatment, and aerosol hygroscopicity. Simulated macrophysical cloud properties are found to be insensitive in this non-precipitating case, but microphysical properties are especially sensitive to bulk microphysics supersaturation treatment and aerosol hygroscopicity.« less
Bauer, Georg; Gamnitzer, Peter [Institute for Computational Mechanics, Technische Universität München, Boltzmannstr. 15, 85747 Garching (Germany)] [Institute for Computational Mechanics, Technische Universität München, Boltzmannstr. 15, 85747 Garching (Germany); Gravemeier, Volker, E-mail: vgravem@lnm.mw.tum.de [Institute for Computational Mechanics, Technische Universität München, Boltzmannstr. 15, 85747 Garching (Germany) [Institute for Computational Mechanics, Technische Universität München, Boltzmannstr. 15, 85747 Garching (Germany); Emmy Noether Research Group “Computational Multiscale Methods for Turbulent Combustion”, Technische Universität München, Boltzmannstr. 15, 85747 Garching (Germany); Wall, Wolfgang A. [Institute for Computational Mechanics, Technische Universität München, Boltzmannstr. 15, 85747 Garching (Germany)] [Institute for Computational Mechanics, Technische Universität München, Boltzmannstr. 15, 85747 Garching (Germany)
2013-10-15T23:59:59.000Z
Highlights: •We present a computational method for coupled multi-ion transport in turbulent flow. •The underlying formulation is a variational multiscale finite element method. •It is combined with the isogeometric concept for electrochemical systems. •Coupled multi-ion transport in fully turbulent Taylor–Couette flow is simulated. •This example is an important model problem for rotating cylinder electrodes. -- Abstract: Electrochemical processes, such as electroplating of large items in galvanic baths, are often coupled to turbulent flow. In this study, we propose an isogeometric residual-based variational multiscale finite element method for multi-ion transport in dilute electrolyte solutions under turbulent flow conditions. In other words, this means that the concepts of isogeometric discretization and variational multiscale methods are successfully combined for developing a method capable of simulating the challenging problem of coupled multi-ion transport in turbulent flow. We present a comprehensive three-dimensional computational method taking into account, among others, coupled convection–diffusion-migration equations subject to an electroneutrality constraint in combination with phenomenological electrode-kinetics modeling. The electrochemical subproblem is one-way coupled to turbulent incompressible flow via convection. Ionic mass transfer in turbulent Taylor–Couette flow is investigated, representing an important model problem for rotating-cylinder-electrode configurations. Multi-ion transport as considered here is an example for mass transport at high Schmidt number (Sc=1389). An isogeometric discretization is especially advantageous for the present problem, since (i) curved boundaries can be represented exactly, and (ii) it has been proven to provide very accurate solutions for flow quantities when being applied in combination with residual-based variational multiscale modeling. We demonstrate that the method is robust and provides results which are in good agreement with direct numerical simulation results as well as empirical mass-transfer correlations reported in literature.
Sliding Interfaces for Eddy Current Simulations Raffael Casagrande
Hiptmair, Ralf
Sliding Interfaces for Eddy Current Simulations Raffael Casagrande Supervisor: Prof. Dr. Ralf Interfaces for Eddy Current April 17th, 2013 1 / 25 #12;Outline 1 Introduction Motivation 2 Deriving the eddy current model Maxwell's Equations in a moving frame The eddy current model in a moving frame 3
Gregory L. Eyink
1996-02-19T23:59:59.000Z
We establish and discuss {\\em a priori} estimates on subgrid stress and subgrid flux for filtering schemes used in the turbulence modelling method of Large-Eddy Simulation (LES). Our estimates are derived as rigorous consequences of the exact subgrid stress formulae from Navier-Stokes equations under realistic conditions for inertial-range velocity fields, those conjectured in the Parisi-Frisch ``multifractal model.'' The estimates are shown to be an expression of ``local energy cascade,'' i.e. the dominance of local wavevector triads in the energy transfer. We prove that for nearly any reasonable filter function the LES method defines an energy flux in which local triads dominate in individual realizations, due to cancellation of distant triadic contributions by detailed conservation. A somewhat similar observation of Leslie and Quarini on graded filters in the EDQNM closure is shown to be unrelated to the cancellation we establish in Navier-Stokes solutions. The sharp Fourier cutoff filter is one example which does not satisfy the modest conditions of our proof and, in fact, we show that with that filter the energy transfer in individual realizations at arbitrarily high Reynolds number will be dominated by nonlocal, convective sweeping.
Jagannathan, Shriram
2012-02-14T23:59:59.000Z
. : : : : : : : : : : : : : : : : : : : : : : : : : : : : 53 xvi FIGURE Page 35 (a)The maximum reverse ow velocity is less than 15% of the freestream velocity and the instability associated could be clas- si ed as convective according to Alam and Sandham [5]. (b) A distinct increase in the boundary... 2-D nite di erence scheme. However recent investigations by Alam and Sandham[5] report that two-dimensional simulations are inaccurate in capturing many of the basic physics of separation. In their study, the two-dimensional simulation under...
Multiscale eddy simulation for moist atmospheric convection: Preliminary investigation
Stechmann, Samuel N., E-mail: stechmann@wisc.edu [Department of Mathematics, University of Wisconsin-Madison (United States); Department of Atmospheric and Oceanic Sciences, University of Wisconsin-Madison (United States)
2014-08-15T23:59:59.000Z
A multiscale computational framework is designed for simulating atmospheric convection and clouds. In this multiscale framework, large eddy simulation (LES) is used to model the coarse scales of 100 m and larger, and a stochastic, one-dimensional turbulence (ODT) model is used to represent the fine scales of 100 m and smaller. Coupled and evolving together, these two components provide a multiscale eddy simulation (MES). Through its fine-scale turbulence and moist thermodynamics, MES allows coarse grid cells to be partially cloudy and to encompass cloudy–clear air mixing on scales down to 1 m; in contrast, in typical LES such fine-scale processes are not represented or are parameterized using bulk deterministic closures. To illustrate MES and investigate its multiscale dynamics, a shallow cumulus cloud field is simulated. The fine-scale variability is seen to take a plausible form, with partially cloudy grid cells prominent near cloud edges and cloud top. From earlier theoretical work, this mixing of cloudy and clear air is believed to have an important impact on buoyancy. However, contrary to expectations based on earlier theoretical studies, the mean statistics of the bulk cloud field are essentially the same in MES and LES; possible reasons for this are discussed, including possible limitations in the present formulation of MES. One difference between LES and MES is seen in the coarse-scale turbulent kinetic energy, which appears to grow slowly in time due to incoherent stochastic fluctuations in the buoyancy. This and other considerations suggest the need for some type of spatial and/or temporal filtering to attenuate undersampling of the stochastic fine-scale processes.
Coupled Mesoscale-Large-Eddy Modeling of Realistic Stable Boundary Layer Turbulence
Wang, Yao; Manuel, Lance
2013-01-01T23:59:59.000Z
Site-specific flow and turbulence information are needed for various practical applications, ranging from aerodynamic/aeroelastic modeling for wind turbine design to optical diffraction calculations. Even though highly desirable, collecting on-site meteorological measurements can be an expensive, time-consuming, and sometimes a challenging task. In this work, we propose a coupled mesoscale-large-eddy modeling framework to synthetically generate site-specific flow and turbulence data. The workhorses behind our framework are a state-of-the-art, open-source atmospheric model called the Weather Research and Forecasting (WRF) model and a tuning-free large-eddy simulation (LES) model. Using this coupled framework, we simulate a nighttime stable boundary layer (SBL) case from the well-known CASES-99 field campaign. One of the unique aspects of this work is the usage of a diverse range of observations for characterization and validation. The coupled models reproduce certain characteristics of observed low-level jets....
Eddy current NDE performance demonstrations using simulation tools
Maurice, L. [EDF - CEIDRE, 2 rue Ampere, 93206 Saint-Denis Cedex 1 (France); Costan, V.; Guillot, E.; Thomas, P. [EDF - R and D, THEMIS, 1, avenue du General de Gaulle, 92141 Clamart (France)
2013-01-25T23:59:59.000Z
To carry out performance demonstrations of the Eddy-Current NDE processes applied on French nuclear power plants, EDF studies the possibility of using simulation tools as an alternative to measurements on steam generator tube mocks-up. This paper focuses on the strategy led by EDF to assess and use code{sub C}armel3D and Civa, on the case of Eddy-Current NDE on wears problem which may appear in the U-shape region of steam generator tubes due to the rubbing of anti-vibration bars.
Fast Solver for Large Scale Eddy Current Non-Destructive Evaluation Problems
Fast Solver for Large Scale Eddy Current Non-Destructive Evaluation Problems Naiguang Lei Advisor: Lalita Udpa Thursday, July 31st, 2014 9:00-11:00am, EB2219 Abstract Eddy current testing plays a very, an alternating magnetic field source generates induced currents, called eddy currents, in an electrically
Model turbulent floods with the Smagorinski large eddy closure
A. J. Roberts; D. J. Georgiev; D. V. Strunin
2008-05-21T23:59:59.000Z
Floods, tides and tsunamis are turbulent, yet conventional models are based upon depth averaging inviscid irrotational flow equations. We propose to change the base of such modelling to the Smagorinksi large eddy closure for turbulence in order to appropriately match the underlying fluid dynamics. Our approach allows for large changes in fluid depth to cater for extreme inundations. The key to the analysis underlying the approach is to choose surface and bed boundary conditions that accommodate a constant turbulent shear as a nearly neutral mode. Analysis supported by slow manifold theory then constructs a model for the coupled dynamics of the fluid depth and the mean turbulent lateral velocity. The model resolves the internal turbulent shear in the flow and thus may be used in further work to rationally predict erosion and transport in turbulent floods.
Simulation for the assessment of wall thinning using eddy current method
Cheng, W.; Komura, I. [NDE Center, Japan Power Engineering and Inspection Corporation, Yokohama 230-0044 (Japan)
2011-06-23T23:59:59.000Z
A pipe with protective cladding and insulation was simplified to a four-layered structure when the diameter of a pipe is large enough, and analytical solutions for sinusoidal and pulsed wave excitation were derived. Simulation implemented by using the analytical solutions showed that sinusoidal excitation is not appropriate for the monitoring of inner thinning, while pulsed eddy current method can be used to measure wall-thickness regardless of inner or outer thinning by using the decay rate of log(Bz) as a particular parameter to evaluate wall thickness.
Lundquist, Katherine Ann
2010-01-01T23:59:59.000Z
large-eddy simulations within mesoscale simulations for windEddy Simulation of a Mesoscale Convective Internal Boundary185, 1957. Pielke, R. , Mesoscale Meteorological Modeling,
Marusic, Ivan
Large-scale eddies and their role in entrainment in turbulent jets and wakes Jimmy Philip and Ivan. Fluids 24, 086101 (2012) The influence of large-scale structures on entrainment in a decelerating://pof.aip.org/about/rights_and_permissions #12;PHYSICS OF FLUIDS 24, 055108 (2012) Large-scale eddies and their role in entrainment in turbulent
Study on eddy current losses and shielding measures in large power transformers
Chen Yongbin; Yu Hainian [Shenyang Transformer Research Inst. (China)] [Shenyang Transformer Research Inst. (China); Yang Junyou; Tang Renyuan [Shenyang Polytechnic Univ. (China)] [Shenyang Polytechnic Univ. (China)
1994-09-01T23:59:59.000Z
The improved T-{Omega} method is applied to the computation of the three dimensional eddy current field in a 360MVA/500kV large power transformer, the structure of which is complicated. The different cases of tank wall with magnetic shunt, aluminum screen or without any shield are analyzed. The relations between eddy current losses and the materials, structure and size of the tank shield are presented. Compared with a parallel magnetic shunt arrangement, the vertical magnetic shunt reduces stray losses by 63.8%. The optimal thickness or the vertical magnetic shunt Is 10mm. The magnetic shunt should be spread over 0.5mm at both ends of windings in the 360MVA/500kV large power transformer.
Large Eddy Simulation (LES) Applied to Advanced Engine Combustion Research
Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site
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 DeliciousPlasma | Department of EnergyBrakingDepartment ofProgram Management PlanLPPLactationLand andThe new|
Large eddy simulation of turbulence within heat exchangers
Pruitt, John Myron
1992-01-01T23:59:59.000Z
by the Electric Power Research Institute (EPRI), and continued within the Nuclear Engineering Department of Texas A&M University. Previous investigation has predicted the turbulent characteristics within the waterbox region of the Westinghouse D-4 steam... generator. Further investigation has included single and multiple tube configurations using coarse meshes. EPRI has supported this effort with many experimental investigations designed to provide data for comparison and validation of the technique...
Large Eddy Simulations of Jet Flow Interactions Within Rod Bundles
Salpeter, Nathaniel O.
2010-07-14T23:59:59.000Z
The present work investigates the turbulent jet flow mixing of downward impinging jets within a staggered rod bundle based on previous experimental work. The two inlet jets had Reynold's numbers of 11,160 and 6,250 and were chosen to coincide...
Vehicle Technologies Office Merit Review 2015: Large Eddy Simulation...
Office of Environmental Management (EM)
Research Presentation given by Sandia National Laboratories at 2015 DOE Hydrogen and Fuel Cells Program and Vehicle Technologies Office Annual Merit Review and Peer Evaluation...
Vehicle Technologies Office Merit Review 2015: Large Eddy Simulation (LES)
Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site
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 DeliciousPlasma |Efficiency Â» Searchto IncreaseIntake Event- NTEImproved InternalLife Cycle
LARGE EDDY SIMULATION OF NATURAL AND MIXED CONVECTION AIRFLOW INDOORS
Chen, Qingyan "Yan"
coordinate Greek symbols : Thermal expansion coefficient t : Time step : Filter size : Kinematic viscocity convection, such as winter heating by a baseboard heater; forced convection, such as free cooling in shoulder
Large Eddy Simulations of Jet Flow Interactions Within Rod Bundles
Salpeter, Nathaniel O.
2010-07-14T23:59:59.000Z
5,603,819 4 2.00mm 4,439,612 5 3.00mm 4,237,281 19 a) 0.65mm Cell Size b) 0.75mm Cell Size b) 0.9mm Cell Size c) 1.2mm Cell Size d) 2mm Cell Size e) 3mm Cell Size... ................................................................................................. 16 2.3. Grid Sensitivity Study Results and Discussion .............................................. 23 2.4. Analysis Methods ........................................................................................... 31 3. RESULTS...
Large Eddy Simulation (LES) Applied to Advanced Engine Combustion Research
Broader source: Energy.gov [DOE]
2013 DOE Hydrogen and Fuel Cells Program and Vehicle Technologies Program Annual Merit Review and Peer Evaluation Meeting
Fox-Kemper, B.
A parameterization for the restratification by finite-amplitude, submesoscale, mixed layer eddies, formulated as an overturning streamfunction, has been recently proposed to approximate eddy fluxes of density and other ...
Bordoni, Simona
a regime transition as f0 is increased, from an equinox regime (small f0) in which eddy momentum fluxes-dependent simulations, the Hadley cells undergo transitions between a linear equinox regime and a nonlinear, nearly of the nonlinear mean momentum flux divergence in the zonal mo- mentum budget shifts from marginal in the equinox
Sandia Energy - Simulating Turbine-Turbine Interaction
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
of wind-turbine wakes within a turbulent atmospheric boundary layer using a large eddy simulation (LES) method. Current and ongoing work aims to leverage the simulation...
RACORO continental boundary layer cloud investigations. 2. Large...
Office of Scientific and Technical Information (OSTI)
become publicly available on June 19, 2016 Title: RACORO continental boundary layer cloud investigations. 2. Large-eddy simulations of cumulus clouds and evaluation with...
ACCOLADES: A Scalable Workflow Framework for Large-Scale Simulation...
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
A Scalable Workflow Framework for Large-Scale Simulation and Analyses of Automotive Engines Title ACCOLADES: A Scalable Workflow Framework for Large-Scale Simulation and...
Large-scale gyrokinetic particle simulation of
Oliker, Leonid
areas of research including plasma astrophysics and fusion energy science. Fusion is the power source that are still needed to make fusion energy a practical realization. Research in plasma science requiresLarge-scale gyrokinetic particle simulation of microturbulence in magnetically confined fusion
White, D
2009-04-30T23:59:59.000Z
Simulation of three-dimensional transient eddy current problems is important to numerous applications. The Finite Element Method (FEM) has proven be to be powerful numerical technique for solving the Partial Differential Equations (PDE) describing eddy currents. In order to solve the PDE, boundary conditions must be provided, and in many applications the boundary conditions are not known explicitly but can be provided by a Resistor-Inductor-Capacitor (RLC) circuit model. The emphasis of this paper is on an efficient and exact coupling of the RLC network equations with the FEM equations. The coupling is based on an exact linear algebra identity known as the Sherman-Morrison-Woodbury (SMW) formula. One advantage of this approach is that the FEM matrices are not modified. This is important if a fast 'black-box' solver is available for the FEM matrices, these solvers typically require that the matrices have certain mathematical properties and these properties are not modified by the SMW approach. A second advantage is that the SMW approach is valid for an arbitrary number of independent external circuits.
NREL Develops Simulations for Wind Plant Power and Turbine Loads (Fact Sheet)
Not Available
2012-04-01T23:59:59.000Z
NREL researchers are the first to use a high-performance computing tool for a large-eddy simulation of an entire wind plant.
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)41clothThe Bonneville PowerTariff Pages default Sign In AboutIsrelocates IBreakingBurns,Rusty
Large-Eddy Simulation for Green Energy and Propulsion Systems | Argonne
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)41clothThe Bonneville PowerTariff Pages default Sign In AboutIsrelocates IBreakingBurns,RustyLargefor High Energy
Large Eddy Simulation (LES) Applied to LTC/Diesel/Hydrogen Engine
Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site
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 DeliciousPlasma | Department of EnergyBrakingDepartment ofProgram Management PlanLPPLactationLand andThe
Large Eddy Simulation (LES) Applied to LTC/Diesel/Hydrogen Engine
Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site
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 DeliciousPlasma | Department of EnergyBrakingDepartment ofProgram Management PlanLPPLactationLand andTheCombustion
Large Eddy Simulation (LES) Applied to Low-Temperature and Diesel Engine
Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site
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 DeliciousPlasma | Department of EnergyBrakingDepartment ofProgram Management PlanLPPLactationLand
Flame Stability Analysis in an Ultra Compact Combustor Using Large-Eddy Simulation
Raman, Venkat
of the configuration. The high enthalpy in this region interacts with the incoming spray droplets leading progress variable Thermochemical composition vector Zv Subfilter mixture fraction variance Graduate Student
Large Eddy Simulation of Supersonic Combustion using Direct Quadrature Method of Moments
Raman, Venkat
be used. Transport of the joint filtered density function (FDF) of the thermochemical composition vector are based on a conserved scalar approach, where the gas- phase thermochemical state is mapped through the enthalpy evolution depends on the local pressure and velocity fields in supersonic flows, the gas
Raman, Venkat
Crossflow Sin Hyen Kim , Optimulation, LLC., Austin, Texas, 78731, USA Pratik Donde , Venkat Raman crossflow (JISC) provide e cient mixing and flame stabilization in su- personic combustion. A LES-DQMOM based comprehensive methodology was developed and calculated sonic jet in Mach 2.0 crossflow
LARGE EDDY SIMULATION FOR TURBULENT MHD FLOWS A. LABOVSKY AND C. TRENCHEA
Trenchea, Catalin
problems such as plasma confinement, controlled thermonuclear fusion, liquid-metal cooling of nuclear
Turbulence prediction in two- and three-dimensional bundle flows using Large Eddy Simulation
Ibrahim, Wael Abdul-Hamid
1994-01-01T23:59:59.000Z
using both models. The results are then compared with the experimental data obtained previously from the experiment conducted at the Electrical Power Research Institute (EPRI NP-5540, May 1988b). For the purpose of completeness, LES is further used...
Ayache, Simon
2012-09-03T23:59:59.000Z
level of geometric complexity. It has been carried out during a secondment to work at Rolls-Royce plc with the aim of sharing fundamental and applied research developments. In the PhD thesis, Proper Orthogonal Decomposition (POD) has been systematically...
Large-Eddy Simulation of the Bachalo-Johnson Flow, with Shock...
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
proposals for carbon capture and sequestration also involve supersonic flows in the compressors. This project will focus on the upper surface of a transport aircraft wing,...
Large Eddy Simulation of laser ignition and compressible reacting flow in a rocket-like
Paris-Sud XI, Université de
combustion devices. The technical needs for internal-combustion (IC) engines and aircraft combustors have in a rocket engine is a critical problem for combustion cham- ber design. Delayed ignition may lead to high without failure. The combustion initiation in rocket engines is usually based on pyrotechnic devices
Large-Eddy Simulation of Pulverized Coal Jet Flame -Effect of Oxygen Concentration on NOx formation
Muto, Masaya; Watanabe, Hiroaki; Kurose, Ryoichi; Komori, Satoru; Balusamy, Saravanan; Hochgreb, Simone
2014-11-13T23:59:59.000Z
those by using other fossil fuels [1]. It is therefore important to develop clean coal technology for pulverized coal fired power plants, in order to con- trol such emissions and to reduce the environmental impact. ct of CO2, carbon a key technology, l...
Large-Eddy Simulation of Pulverized Coal Jet Flame -Effect of Oxygen Concentration on NOx formation
Muto, Masaya; Watanabe, Hiroaki; Kurose, Ryoichi; Komori, Satoru; Balusamy, Saravanan; Hochgreb, Simone
2015-01-01T23:59:59.000Z
than those by using other fossil fuels [1]. It is therefore important to develop clean coal technology for pulverized coal fired power plants, in order to control such emissions and to reduce the environmental impact. Regarding the reduction... of environmental impact of CO2, carbon capture and sequestration (CCS) is expected as a key technology, and it is believed that oxy-fuel pulverized coal combus- tion, in which gas mixture of oxygen (O2) and CO2 are used instead of air as oxidizer, has advantages...
Large-Eddy Simulations of Longitudinal Vortices Embedded in a Turbulent Boundary Layer
Mittal, Rajat
quantity ^ = test-filtered quantity = quantity in wall unit 0 = fluctuation component I. Introduction noise and cavitation in hydraulic pumps. This has motivated recent experiments performed by Kuhl [5] and Ma [6]. They made 3-D laser Doppler anemometer (LDA) [5] and hot-wire [6] measurements of near
DIRECT AND LARGE EDDY SIMULATIONS OF A BOTTOM EKMAN LAYER UNDER AN EXTERNAL STRATIFICATION
Taylor, John R.
the DNS are used to evaluate the LES. The mean velocity profile, mean temperature gradient, and boundary be approximated as an adiabatic boundary with the excep- tion of isolated geothermal hotspots. However
Large-eddy simulation of swirling particle-laden flows in a coaxial-jet combustor
Mahesh, Krishnan
, the resulting droplets evaporate/condense and collide/coalesce, fuel and oxidizer then mix yielding spray. Mahesh b , P. Moin c , J.C. Oefelein d a Department of Mechanical Engineering, Stanford University, Bldg
Analysis of Multiple Scalar Large-Eddy Simulation/Probability Density Function Formulation
Raman, Venkat
in the spray flame. Filtered density uj Filtered velocity W Filtered evaporation source term ~P Filtered term in PDF transport equation G() Spray evaporation correction term in PDF transport equation d for Turbulent Spray Combustion C. R. Heye , H. Koo and V. Raman Department of Aerospace Engineering
Large-eddy Simulation of Realistic Gas Turbine Combustors , & Apte, S. V.
Apte, Sourabh V.
for liquid fuel atomization, droplet evaporation, droplet deformation & drag, and turbulent combustion due to chemical reactions. A systematic validation and verification study of the individual spray of Mechanical Engineering, Associate Fellow, AIAA, moin@stanford.edu Research Associate, Department
Kewlani, Gaurav
2014-01-01T23:59:59.000Z
High efficiency, low emissions and stable operation over a wide range of conditions are some of the key requirements of modem-day combustors. To achieve these objectives, lean premixed flames are generally preferred as ...
Kogan, Yefim L.; Kogan, Zena N.; Mechem, David B.
2009-08-01T23:59:59.000Z
Cloud microphysical parameterizations and retrievals rely heavily on knowledge of the shape of drop size distributions (DSDs). Many investigations assume that DSDs in the entire or partial drop size range may be approximated ...
Large-eddy simulation of swirling particle-laden flows in a coaxial-jet combustor
Apte, Sourabh V.
combustion engines, liquid and solid propellant rocket motors, gas-turbine aircraft engines, International. In gas turbine combustors, for example, the liquid fuel jet undergoes primary and secondary atomization is performed. A mixture of air and lightly loaded, spherical, glass-particles with a prescribed size
Evaluating Subgrid-Scale Models for Large-Eddy Simulation of Turbulent Katabatic Flow
Fedorovich, Evgeni
of LES for reproducing stably-stratified turbulent boundary layers [2]. Under stably-stratified conditions, the characteristic length scale of the small-scale turbulent motions decrease, placing a larger analytically for a laminar slope flow in a stably- stratified environment. The Prandtl solution
Pierce, Stephen
Oceanographic Institution, Woods Hole, MA, USA. 4 Naval Air Systems Command, Patuxent River, MD, USA
Large-Eddy Simulation of a Supersonic Inlet-Isolator Heeseok Koo
Raman, Venkat
in a dual-mode scramjet engine that provides stable compressed flow to the combustor. However function in weighted essentially nonoscillatory scheme cp = heat capacity at constant pressure e = nonchemical, sensible energy, m2 =s2 et = nonchemical total energy, m2 =s2 F = flux G = filtering kernel h
Large-Eddy Simulation of a Supersonic Inlet-Isolator Heeseok Koo1
Raman, Venkat
The University of Texas at Austin, Austin, Tx, 78712 The isolator is an important flow section in a dual in hyperviscosity model cp = heat capacity at constant pressure cj = weighting function in WENO scheme e = non-chemical, sensible energy, m2 /s2 et = non-chemical total energy, m2 /s2 F = flux h = isolator height IP
Turbulence prediction using the large eddy simulation method in staggered and inlined bundles
Barsamian, Hagop Raffi
1994-01-01T23:59:59.000Z
and not the cause of the instability (France and Hopkins, 1994). This process has been studied by Song and Yuan (1990) for both primary and secondary vortices with relative success, as well as Polak and Weaver (1994) in triangular tube arrays. The forces...
Direct and Large-Eddy Simulations of a Turbulent Flow with Effusion
Nicoud, Franck
to be cooled. One possibility often chosen in gas turbines is to use multiperforated walls to produce in actual gas turbines make any measurement very challenging. · the number of holes make accurate test rig. 1 Introduction In almost all the systems where combustion occurs, solid boundaries need
Large-Eddy Simulation of the Acoustic Response of a Perforated Plate
Nicoud, Franck
the unsteady combustion process and the acoustic modes in the chamber. Notably, in aeronautical gas turbines the shape of the jet separation at the aperture inlet. II. Introduction Nowadays, competitive gas turbines have to prove a low pollutant emission capability. This is often ob- tained by using lean combustion
Acoustic modeling of perforated plates with bias flow for Large-Eddy Simulations
Mendez, Simon
is then addressed in the context of thermo- acoustic instabilities of gas turbine combustion chambers. Details, competitive gas turbines have to prove a low pollutant emission capability. For example, Lean Premixed and the acoustic modes in the chamber. Notably, in aeronautical gas turbines, one needs to consider the fact
Massively Parallel Spectral Element Large Eddy Simulation of a Turbulent Channel Using Wall Models
Rabau, Joshua I
2013-05-01T23:59:59.000Z
Wall-bounded turbulent flows are prevalent in engineering and industrial applications. Walls greatly affect turbulent characteristics in many ways including production and propagation of turbulent stresses. While computational ...
Direct Numerical Simulation of the Flow in a Pebble Bed
Ward, Paul
2014-06-24T23:59:59.000Z
at Argonne National Laboratory, to conduct both large eddy simulation (LES) and direct numerical simulation (DNS) of fluid flow through a single face-centered cubic sphere lattice with periodic boundary conditions. Multiple LES were conducted with varying...
Large-Scale Hybrid Dynamic Simulation Employing Field Measurements
Huang, Zhenyu; Guttromson, Ross T.; Hauer, John F.
2004-06-30T23:59:59.000Z
Simulation and measurements are two primary ways for power engineers to gain understanding of system behaviors and thus accomplish tasks in system planning and operation. Many well-developed simulation tools are available in today's market. On the other hand, large amount of measured data can be obtained from traditional SCADA systems and currently fast growing phasor networks. However, simulation and measurement are still two separate worlds. There is a need to combine the advantages of simulation and measurements. In view of this, this paper proposes the concept of hybrid dynamic simulation which opens up traditional simulation by providing entries for measurements. A method is presented to implement hybrid simulation with PSLF/PSDS. Test studies show the validity of the proposed hybrid simulation method. Applications of such hybrid simulation include system event playback, model validation, and software validation.
Bailey-Kellogg, Chris
Intelligent Simulation Tools for Mining Large Scienti#12;c Data Sets 1 Intelligent Simulation Tools for Mining Large Scienti#12;c Data Sets Feng ZHAO Xerox Palo Alto Research Center 3333 Coyote Hill Road, Palo. Keywords Intelligent simulation, Scienti#12;c data mining, Qualitative reasoning, Reasoning about physical
van Zanten, Margreet C; Stevens, Bjorn; Nuijens, Louise; Siebesma, A Pier; Ackerman, A. S.; Burnet, F.; Cheng, A.; Couvreux, F.; Jiang, H.; Khairoutdinov, M.; Kogan, Yefim L.; Lewellen, D. C.; Mechem, David B.
2011-06-28T23:59:59.000Z
Twelve large-eddy simulations, with a wide range of microphysical representations, are compared to each other and to independent measurements. The measurements and the initial and forcing data for the simulations are taken ...
Effects of Sea-Salt Aerosols on Precipitation in Simulations of Shallow Cumulus
Kogan, Yefim L.; Mechem, David B.; Choi, Kityan
2012-02-01T23:59:59.000Z
A suite of large-eddy simulations with size-resolving microphysical processes was performed in order to assess effects of sea-salt aerosols on precipitation process in trade cumulus. Simulations based on observations from ...
PANS method of turbulence: simulation of high and low Reynolds number flows past a circular cylinder
Lakshmipathy, Sunil
2006-04-12T23:59:59.000Z
cylinder are performed at ReD 140,000 and ReD 3900 using the PANS model. The high Reynolds number PANS results are compared with experimental results from Cantwell and Coles, Large Eddy Simulation results from Breuer, and Detached Eddy Simulation results...
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)41clothThe Bonneville Power Administration wouldDecember 2014Field Campaign: PotentialOilignition engineDiagnosis of
Technical Note Correction of Eddy-Current Distortions in Diffusion
Technical Note Correction of Eddy-Current Distortions in Diffusion Tensor Images Using the Known,2 Purpose: To correct eddy-current artifacts in diffusion ten- sor (DT) images without the need to obtain- tortions caused by eddy currents induced by large diffusion gradients. We propose a new postacquisition
Not Available
2011-02-01T23:59:59.000Z
Researchers at the National Renewable Energy Laboratory (NREL) develop a high-fidelity large-eddy simulation model designed to predict the performance of large wind plants with a higher degree of accuracy than current models.
An Evaluation of the Network Simulators in Large-Scale Distributed Simulations
Ciraci, Selim; Akyol, Bora A.
2011-11-13T23:59:59.000Z
This is a survey paper about the state-of-the-art in large-scale network simulation. Networks for the smart grids are characterized by millions of sensor nodes exchanging information about the status of the grid. This information exchange must be realized reliably and efficiently due to the mission critical nature of the power grid. Hence, the applications and the network protocols developed for the smart grid need go through rigorous testing and analysis before deployment. Developers usually do not have access to such a large-scale network that can be used as a controlled test-bed; therefore, network simulation becomes an essential tool for testing. Network simulation is a well studied problem in the literature and there are various widely used network simulators. These simulators can be adopted for testing applications and protocols of the smart grid. Due to the scale of these networks, parallel/distributed simulations need to be conducted. Even though most network simulators support distributed simulations, generating a large-scale network model to simulate can still be a cumbersome task. In this survey, we describe a selection of commonly used network simulators and evaluate them with respect to the following features that can aid users in distributed simulations of large-scale networks: transparency of setting up distributed simulation, automated topology generation, information hiding, lightweight routing protocols, network error simulation, evaluation of the network model during simulation and trace analysis tools. As a complementary result, we identify two issues with network simulators that can be addressed with runtime steering methods.
Toward Improved Support for Loosely Coupled Large Scale Simulation Workflows
Boehm, Swen [ORNL] [ORNL; Elwasif, Wael R [ORNL] [ORNL; Naughton, III, Thomas J [ORNL; Vallee, Geoffroy R [ORNL] [ORNL
2014-01-01T23:59:59.000Z
High-performance computing (HPC) workloads are increasingly leveraging loosely coupled large scale simula- tions. Unfortunately, most large-scale HPC platforms, including Cray/ALPS environments, are designed for the execution of long-running jobs based on coarse-grained launch capabilities (e.g., one MPI rank per core on all allocated compute nodes). This assumption limits capability-class workload campaigns that require large numbers of discrete or loosely coupled simulations, and where time-to-solution is an untenable pacing issue. This paper describes the challenges related to the support of fine-grained launch capabilities that are necessary for the execution of loosely coupled large scale simulations on Cray/ALPS platforms. More precisely, we present the details of an enhanced runtime system to support this use case, and report on initial results from early testing on systems at Oak Ridge National Laboratory.
The use of large plot rainfall simulation to investigate
Sorenson, Joshua Russell
2006-04-12T23:59:59.000Z
In this study, large scale rainfall simulation was used to evaluate runoff generation from canopy and intercanopy areas within an ashe juniper woodland of the Edwards Plateau. One 3 x 12 m site was established beneath the canopy of mature ashe...
SIMULATING LARGE-SCALE STRUCTURE FORMATION FOR BSI POWER SPECTRA
V. Mueller
1995-05-30T23:59:59.000Z
A double inflationary model provides perturbation spectra with enhanced power at large scales (Broken Scale Invariant perturbations -- BSI), leading to a promising scenario for the formation of cosmic structures. We describe a series of high-resolution PM simulations with a model for the thermodynamic evolution of baryons in which we are capable of identifying 'galaxy' halos with a reasonable mass spectrum and following the genesis of large and super-large scale structures. The power spectra and correlation functions of 'galaxies' are compared with reconstructed power spectra of the CfA catalogue and the correlation functions of the Las Campanas Deep Redshift Survey.
Tidal Residual Eddies and their Effect on Water Exchange in Puget Sound
Yang, Zhaoqing; Wang, Taiping
2013-08-30T23:59:59.000Z
Tidal residual eddies are one of the important hydrodynamic features in tidally dominant estuaries and coastal bays, and they could have significant effects on water exchange in a tidal system. This paper presents a modeling study of tides and tidal residual eddies in Puget Sound, a tidally dominant fjord-like estuary in the Pacific Northwest coast, using a three-dimensional finite-volume coastal ocean model. Mechanisms of vorticity generation and asymmetric distribution patterns around an island/headland were analyzed using the dynamic vorticity transfer approach and numerical experiments. Model results of Puget Sound show that a number of large twin tidal residual eddies exist in the Admiralty Inlet because of the presence of major headlands in the inlet. Simulated residual vorticities near the major headlands indicate that the clockwise tidal residual eddy (negative vorticity) is generally stronger than the anticlockwise eddy (positive vorticity) because of the effect of Coriolis force. The effect of tidal residual eddies on water exchange in Puget Sound and its sub-basins were evaluated by simulations of dye transport. It was found that the strong transverse variability of residual currents in the Admiralty Inlet results in a dominant seaward transport along the eastern shore and a dominant landward transport along the western shore of the Inlet. A similar transport pattern in Hood Canal is caused by the presence of tidal residual eddies near the entrance of the canal. Model results show that tidal residual currents in Whidbey Basin are small in comparison to other sub-basins. A large clockwise residual circulation is formed around Vashon Island near entrance of South Sound, which can potentially constrain the water exchange between the Central Basin and South Sound.
Eddy Current Model of Ball Lightning
Shelton, J D
2011-01-01T23:59:59.000Z
Eddy Current Model of Ball Lightning Calculations show that high-energy ball lightning may consist of a ball of plasma containing a large circular electric current arising as an eddy current generated by lightning. Synthetic ball lightning might serve as a method of plasma confinement for purposes of nuclear fusion. In this paper, three articles concerning ball lightning and the related phenomenon of large ball lightning are combined to provide insight into this rarely glimpsed occurrence.
Eddy Current Model of Ball Lightning
J. D. Shelton
2011-02-07T23:59:59.000Z
Eddy Current Model of Ball Lightning Calculations show that high-energy ball lightning may consist of a ball of plasma containing a large circular electric current arising as an eddy current generated by lightning. Synthetic ball lightning might serve as a method of plasma confinement for purposes of nuclear fusion. In this paper, three articles concerning ball lightning and the related phenomenon of large ball lightning are combined to provide insight into this rarely glimpsed occurrence.
DOE Data Explorer [Office of Scientific and Technical Information (OSTI)]
Plimpton, Steve; Thompson, Aidan; Crozier, Paul
LAMMPS (http://lammps.sandia.gov/index.html) stands for Large-scale Atomic/Molecular Massively Parallel Simulator and is a code that can be used to model atoms or, as the LAMMPS website says, as a parallel particle simulator at the atomic, meso, or continuum scale. This Sandia-based website provides a long list of animations from large simulations. These were created using different visualization packages to read LAMMPS output, and each one provides the name of the PI and a brief description of the work done or visualization package used. See also the static images produced from simulations at http://lammps.sandia.gov/pictures.html The foundation paper for LAMMPS is: S. Plimpton, Fast Parallel Algorithms for Short-Range Molecular Dynamics, J Comp Phys, 117, 1-19 (1995), but the website also lists other papers describing contributions to LAMMPS over the years.
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
& Reliability Projects Expand Projects Skip navigation links Line Projects Big Eddy-Knight Central Ferry Lower Monumental Grand Coulee Transmission Line Replacement...
Interface Exchange as an Indicator for Eddy Heat Transport
Petersen, Mark R. [Los Alamos National Laboratory; Williams, Sean J. [Los Alamos National Laboratory; Hecht, Matthew W. [Los Alamos National Laboratory; Maltrud, Mathew E. [Los Alamos National Laboratory; Hamann, Bernd [U of California Davis; Patchett, John M. [Los Alamos National Laboratory; Ahrens, James P. [Los Alamos National Laboratory
2012-06-12T23:59:59.000Z
The ocean contains many large-scale, long-lived vortices, called mesoscale eddies, that are believed to have a role in the transport and redistribution of salt, heat, and nutrients throughout the ocean. Determining this role, however, has proven to be a challenge, since the mechanics of eddies are only partly understood; a standard definition for these ocean eddies does not exist and, therefore, scientifically meaningful, robust methods for eddy extraction, characterization, tracking and visualization remain a challenge. In order to shed light on the nature and potential roles of eddies, we have combined our previous research on eddy identification and tracking, and have used those approaches as the basis for analysis-driven computational experiments on the nature of eddies. Based on the resulting visualizations of eddy behavior, we have devised a new metric to characterize the transfer of water into and out of eddies across their boundary, and have developed visualization methods for this new metric to provide clues about the role eddies play in the global ocean and, potentially, climate change.
Paris-Sud XI, Université de
A new database generation method combining maximin method and kriging prediction for eddy-current@evt.bme.hu Abstract: The accurate numerical simulation of the eddy- current testing (ECT) experiments usually requires-based adaptive methodology which yields to databases optimized to the given problem. Keywords: eddy-current
AN EFFICIENT EDDY CURRENT MODEL FOR NONLINEAR MAXWELL EQUATIONS WITH LAMINATED CONDUCTORS
Zheng, Weiying
AN EFFICIENT EDDY CURRENT MODEL FOR NONLINEAR MAXWELL EQUATIONS WITH LAMINATED CONDUCTORS XUE JIANG AND WEIYING ZHENG Abstract. In this paper, we propose a new eddy current model for the nonlinear Maxwell equations with laminated conductors. Direct simulation of three-dimensional (3D) eddy currents in grain
Sun, Long
2011-01-01T23:59:59.000Z
losses of a flat-plate collector, Solar Energy 35, 15–19.from outer cover of solar collectors, Renew. Energ. 10 (4)
Mirocha, Jeffrey D.; Kosovi?, Branko
2010-01-01T23:59:59.000Z
to the surface of the snow/ice pack is often prevented byheat ?ux from the snow/ice pack interior, which constrainsover the Arctic Ocean snow/ice pack during clear-sky, winter
Sun, Long
2011-01-01T23:59:59.000Z
When the convection heat transfer model is well validated,models, convection heat transfer model is often over-and a convection heat transfer model with local accuracy is
Large-eddy simulation/probability density function modeling of a non-premixed CO/H2
;applicable to practical devices such as gas turbine combustors and internal combustion engines [2 4]. In LES School of Mechanical and Aerospace Engineering, Cornell University, Ithaca, NY 14853, USA b Combustion PDFs of compositions. Ó 2012 The Combustion Institute. Published by Elsevier Inc. All rights reserved
Chow, Fotini Katopodes
reflect off grid refinement interfaces, specifically on the outflow boundary from a fine to a coarse grid reflection off grid refinement interfaces by forcing the filter-resolved scale on a fine grid to equal
wind plants, reduce the cost of wind energy, and save wind plant developers millions of dollars in lost than current models. As the market for wind energy grows, wind turbines and wind plants are becoming predicted. Wind plant underperformance has become an industry-wide issue that could cost developers millions
DeCroix, D. S. (David S.)
2002-01-01T23:59:59.000Z
In October 2000, the US Department of Energy, along with NOAA and several other government labs and universities, conducted the Vertical Transport and Mixing Experiment (VTMX) and URBAN2000 field programs in Salt Lake City, Utah (Alwine et al., 2002). The VTMX program focused on the basin-scale flow regime, where the URBAN2000 component focused on transport and dispersion in the downtown Salt Lake City area. In this paper, we will focus on a specific Intensive Operations Period, IOP-10, which occurred on October 25-26, 2000. IOP-16 was chosen because the winds in the downtown area were fairly weak and variable early in the experiment, and became more windy in the later part of the IOP. The local conditions were influenced by a shortwave ridge, and were cloudy, with a weak and very shallow surface inversion, and light mean southerly flow over the area. An inert tracer gas, SF6, was released downtown Salt Lake City for a duration of one hour at three separate times on 26 October 2000, 01:00-02:00, 03:00-04:00, and 05:00-06:00 MDT. This paper will focus on the first release time, from 01:00-02:00 MDT.
Zhang, Huangwei; Garmory, Andrew; Cavaliere, Davide E.; Mastorakos, Epaminondas
2014-06-25T23:59:59.000Z
of around 100,000 polyhedral cells and is refined in the fuel jet and flame regions, thereby leading to 100-200 LES cells within one CMC cell there. This CMC mesh refinement is expected to be useful here because fine local CMC resolution can better... . In CMC, h=0 corresponds to air and h=1 to pure fuel, both at 298 K. The fully burning steady solutions with 10 50 sN ?? from a 0D-CMC calculation are used to initialize all the CMC cells. Inert mixing solutions are injected in the air and fuel inlets...
Oberai, Assad A [Rensselaer Polytechnic Instistute
2013-07-16T23:59:59.000Z
In the report we present a summary of the new models and algorithms developed by the PI and the students supported by this grant. These developments are described in detail in ten peer-reviewed journal articles that acknowledge support from this grant.
Jagannathan, Shriram
2012-02-14T23:59:59.000Z
-Chairs of Committee, Andrew Duggleby Taher Schobeiri Committee Members, Hamn-Ching Chen Head of Department, Dennis O?Neal December 2010 Major Subject: Mechanical Engineering iii ABSTRACT Characterizing the Separation and Reattachment of Suction Surface...
Under consideration for publication in J. Fluid Mech. 1 Large-eddy simulation of a bi-periodic
Mendez, Simon
In gas turbines, the solid parts such as the turbine blades or the liner of the combustion chamber the hot products. However, the application of transpiration-based technology to gas turbines is impossible. One possibility, widely employed for combustion chamber walls, is to use multi-perforated walls
Sun, Long
2011-01-01T23:59:59.000Z
pollution. In this research numerical methods are used to investigate some basic turbulent and thermal
Large-Scale Atomistic Simulations of Material Failure
DOE Data Explorer [Office of Scientific and Technical Information (OSTI)]
Abraham, Farid [IBM Almaden Research; Duchaineau, Mark [LLNL; Wirth, Brian [LLNL; Heidelberg,; Seager, Mark [LLNL; De La Rubia, Diaz [LLNL
These simulations from 2000 examine the supersonic propagation of cracks and the formation of complex junction structures in metals. Eight simulations concerning brittle fracture, ductile failure, and shockless compression are available.
Preliminary Investigations of Eddy Current Effects on a Spinning Disk
Piggott, W T; Walston, S; Mayhall, D
2006-09-08T23:59:59.000Z
The design of the positron source target for the International Linear Collider (ILC) envisions a Ti6Al4V wheel rotating in a large magnetic field (5-10 Tesla) being impacted by a photon beam to produce positrons. One of the many challenges for this system is determining how large a motor will be needed to spin the shaft. The wheel spinning in the magnetic field induces an eddy current in the wheel, which retards the spinning motion of the wheel. Earlier calculations by Mayhall [1] have shown that those eddy forces could be quite large, and resulted in the preliminary design being moved from a solid disk to a rim and spoke design, as shown in Figure 1. A series of experiments with a spinning metal disk were run at the Stanford Linear Accelerator Center (SLAC) to provide experimental validation of the Maxwell 3D simulations. This report will give a brief outline of the experimental setup and results. In addition, earlier work by Smythe [2] will be used to compare with the experimental results.
Computer Energy Modeling Techniques for Simulation Large Scale Correctional Institutes in Texas
Heneghan, T.; Haberl, J. S.; Saman, N.; Bou-Saada, T. E.
1996-01-01T23:59:59.000Z
Building energy simulation programs have undergone an increase in use for evaluating energy consumption and energy conservation retrofits in buildings. Utilization of computer simulation programs for large facilities with multiple buildings, however...
Schmidt, W; Niemeyer, J C
2006-01-01T23:59:59.000Z
We present a one-equation subgrid scale model that evolves the turbulence energy corresponding to unresolved velocity fluctuations in large eddy simulations. The model is derived in the context of the Germano consistent decomposition of the hydrodynamical equations. The eddy-viscosity closure for the rate of energy transfer from resolved toward subgrid scales is localised by means of a dynamical procedure for the computation of the closure parameter. Therefore, the subgrid scale model applies to arbitrary flow geometry and evolution. For the treatment of microscopic viscous dissipation a semi-statistical approach is used, and the gradient-diffusion hypothesis is adopted for turbulent transport. A priori tests of the localised eddy-viscosity closure and the gradient-diffusion closure are made by analysing data from direct numerical simulations. As an a posteriori testing case, the large eddy simulation of thermonuclear combustion in forced isotropic turbulence is discussed. We intend the formulation of the sub...
Large-Scale Molecular Dynamics Simulations for Highly Parallel Infrastructures
Pazúriková, Jana
2014-01-01T23:59:59.000Z
Computational chemistry allows researchers to experiment in sillico: by running a computer simulations of a biological or chemical processes of interest. Molecular dynamics with molecular mechanics model of interactions simulates N-body problem of atoms$-$it computes movements of atoms according to Newtonian physics and empirical descriptions of atomic electrostatic interactions. These simulations require high performance computing resources, as evaluations within each step are computationally demanding and billions of steps are needed to reach interesting timescales. Current methods decompose the spatial domain of the problem and calculate on parallel/distributed infrastructures. Even the methods with the highest strong scaling hit the limit at half a million cores: they are not able to cut the time to result if provided with more processors. At the dawn of exascale computing with massively parallel computational resources, we want to increase the level of parallelism by incorporating parallel-in-time comput...
Paris-Sud XI, Université de
Eddy current evaluation of air-gaps in aeronautical multilayered assemblies using multi in an aeronautical multilayered metallic assembly, by the means of the eddy current method. A behavioural multi, either for simulated or experimental data. KEYWORDS: Non-destructive evaluation, eddy currents, multi
Nabben, Reinhard
-harmonic eddy current model in two dimensions. The first criterion is the robustness with respect Expansions, Eddy- current model AMS subject classifications. 65N30, 35C20, 35J25, 41A60, 35B40, 78M30, 78M35 Introduction. For simulations of the eddy current problem with thin sheets by standard methods, like the finite
Smith, K. Shafer
Mesoscale Eddy Energy Locality in an Idealized Ocean Model IAN GROOMS, LOUIS-PHILIPPE NADEAU, AND K investigates the energy budget of mesoscale eddies in wind-driven two-layer quasigeostrophic simulations of eddy energy are ``nonlocal.'' Many mesoscale parameterizations assume that statistics of the unresolved
A FINITE ELEMENT APPROACH FOR SIMULATING THE QUENCHING OF LARGE ALUMINIUM COMPRESSOR WHEELS
A FINITE ELEMENT APPROACH FOR SIMULATING THE QUENCHING OF LARGE ALUMINIUM COMPRESSOR WHEELS A FINITE ELEMENT APPROACH FOR SIMULATING THE QUENCHING OF LARGE ALUMINIUM COMPRESSOR WHEELS Dirk Büche Aluminum devices such as compressor wheels are typically heat treated in order to achieve the required
Induced Currents, Eddy Currents and
Tobar, Michael
Lecture 11 Induced Currents, Eddy Currents and Maxwell's Equations 1 Faraday Disk Dynamo F = q Eddy Currents We have learnt that changing magnetic fields can induce electric fields in conductors 108 ms-1 16 #12;In this lecture and the next Eddy Currents: We have covered Sect. 29
Simulating large cosmology surveys with calibrated halo models
Lynn, Stuart
2011-11-23T23:59:59.000Z
In this thesis I present a novel method for constructing large scale mock galaxy and halo catalogues and apply this model to a number of important topics in modern cosmology. Traditionally such mocks are created through ...
Turbulent partially premixed combustion: DNS analysis and RANS simulation
Ruan, S.
2013-03-12T23:59:59.000Z
progress in alternative energy technologies, such as solar cell, wind power, fuel cell and nuclear energy, significant limitation remains, such as high capital costs, low energy conversion efficiency, and low public acceptance level due to 1 safety... Numerical Simulation (DNS), Large 10 Eddy Simulation (LES) and Reynolds Averaged Navier-Stokes Simulation (RANS), in the order of decreasing resolution and computational cost and increasing mod- elling assumptions involved. 2.3.1 Direct Numerical Simulation...
Modeling a Large Data Acquisition Network in a Simulation Framework
Colombo, Tommaso; The ATLAS collaboration
2015-01-01T23:59:59.000Z
The ATLAS detector at CERN records particle collision “events” delivered by the Large Hadron Collider. Its data-acquisition system is a distributed software system that identifies, selects, and stores interesting events in near real-time, with an aggregate throughput of several 10 GB/s. It is a distributed software system executed on a farm of roughly 2000 commodity worker nodes communicating via TCP/IP on an Ethernet network. Event data fragments are received from the many detector readout channels and are buffered, collected together, analyzed and either stored permanently or discarded. This system, and data-acquisition systems in general, are sensitive to the latency of the data transfer from the readout buffers to the worker nodes. Challenges affecting this transfer include the many-to-one communication pattern and the inherently bursty nature of the traffic. In this paper we introduce the main performance issues brought about by this workload, focusing in particular on the so-called TCP incast pathol...
Seasonal Modulation of Eddy Kinetic Energy and Its Formation Mechanism in the Southeast Indian Ocean
Qiu, Bo
energy and exert profound impacts on large-scale ocean circulations. Satellite altimeter ob- servations- sociations with the large-scale oceanic circulations and the climate. The global eddy kinetic energy (EKESeasonal Modulation of Eddy Kinetic Energy and Its Formation Mechanism in the Southeast Indian
Parallel domain decomposition for simulation of large-scale power grids
Mohanram, Kartik
of large-scale linear circuits such as power grids. DD techniques that use non-overlapping and overlap that with the proposed parallel DD framework, existing linear circuit simulators can be extended to handle large- scale can be solved independently in parallel using standard techniques for linear system analysis
Meta-Simulation of Large WSN on Multi-core Computers Adnan Iqbal
Brest, Université de
Meta-Simulation of Large WSN on Multi-core Computers Adnan Iqbal NUST/SEECS Islamabad, Pakistan With the advances in wireless communications large scale Wireless Sensor Networks (WSN) are emerging with many such networks. The WSN design problem is of high complexity, and requires robust methodologies, includ- ing
GridMate: A Portable Simulation Environment for Large-Scale Adaptive Scientific Applications
Li, Xiaolin "Andy"
GridMate: A Portable Simulation Environment for Large-Scale Adaptive Scientific Applications: parashar@caip.rutgers.edu Abstract--In this paper, we present a portable sim- ulation environment GridMate for large-scale adaptive scientific applications in multi-site Grid environments. GridMate is a discrete
Boyer, Edmond
866 IEEE TRANSACTIONS ON MAGNETICS, VOL. 44, NO. 6, JUNE 2008 Dynamical Models for Eddy Current accurate dynamical models for representing eddy currents are studied. The simulation of the relay is provided. Index Terms--AC circuit breakers (CBs), eddy currents, magnetic hysteresis, optimization methods
Mesoscale flows in large aspect ratio simulations of turbulent compressible convection
F. Rincon; F. Lignieres; M. Rieutord
2006-11-28T23:59:59.000Z
We present the results of a very large aspect ratio (42.6) numerical simulation of fully compressible turbulent convection in a polytropic atmosphere, and focus on the properties of large-scale flows. Mesoscale patterns dominate the turbulent energy spectrum. We show that these structures, which had already been observed in Boussinesq simulations by Cattaneo et al. (2001), have a genuine convective origin and do not result directly from collective interactions of the smaller scales of the flow, even though their growth is strongly affected by nonlinear transfers. If this result is relevant to the solar photosphere, it suggests that the dominant convective mode below the Sun's surface may be at mesoscales.
Eddy Heat Flux in the Southern Ocean: Response to Variable Wind Forcing ANDREW MCC. HOGG
Miami, University of
kinetic energy, and eddy heat transport to changes in winds is quantified. On interannual time scales- ern Ocean, wind appears to be the most likely energy source for the anomalously large EKE. MeredithEddy Heat Flux in the Southern Ocean: Response to Variable Wind Forcing ANDREW MCC. HOGG Australian
Simulating the Power Consumption of Large-Scale Sensor Network Applications
Simulating the Power Consumption of Large-Scale Sensor Network Applications Victor Shnayder, Mark of the most important as- pects of sensor application design: that of power consump- tion. While simple approximations of overall power usage can be derived from estimates of node duty cycle and com- munication rates
Large-scale simulations of fluctuating biological membranes Andrea Pasqua,1,a
Oster, George
in their computational demands, these approaches are still limited in the scope of fluctuations and response they can's response to a prodding nanorod. © 2010 American Institute of Physics. doi:10.1063/1.3382349 I. INTRODUCTION feasibly capture. Extending computer simulations to examine large scale behaviors such as aggregation
Large-scale molecular dynamics simulation of magnetic properties of amorphous iron under pressure
) Enhanced refrigerant capacity and magnetic entropy flattening using a two-amorphous FeZrB(Cu) compositeLarge-scale molecular dynamics simulation of magnetic properties of amorphous iron under pressure Appl. Phys. Lett. 99, 232501 (2011) Nonlinear motion of magnetic vortex under alternating
Simulation of large-amplitude motion of floating wind turbines using conservation of momentum
Sweetman, Bert
Simulation of large-amplitude motion of floating wind turbines using conservation of momentum Lei equations of motion (EOMs) of a floating wind turbine system using the theorem of conservation of angular wind turbine dynamics software FAST. The concept of highly compliant floating wind turbines
Simulation-based optimization of communication protocols for large-scale wireless sensor networks1
Maróti, Miklós
everyday life more comfortable, e.g. Intelligent Spaces [3]. These sensor networks often use distributed of the wireless sensors may vary greatly, but invariably each of the intelligent sensors is a compact device1 Simulation-based optimization of communication protocols for large-scale wireless sensor networks
Two-dimensional simulations of extreme floods on a large watershed
Julien, Pierre Y.
Two-dimensional simulations of extreme floods on a large watershed John F. England Jr. a,*, Mark L. Velleux b , Pierre Y. Julien c a Bureau of Reclamation, Flood Hydrology, 86-68530, Denver Federal Center September 2007; accepted 14 September 2007 KEYWORDS Flash floods; Flood design; Rainfall runoff; Extreme
Simulation of Large-Area Silicon Solar Cells1 Gernot Heiser2
New South Wales, University of
Simulation of Large-Area Silicon Solar Cells1 Gernot Heiser2 Pietro P. Altermatt3 The University of high-efficiency silicon solar cells. In the past, however, such modelling could only be applied to produce an accurate model of a full-sized high-efficiency solar cell. We demon- strate the power
Dao, Ming
Supplemental Information: Combined simulation and experimental study of large deformation of red, bending energy, constraints of fixed surface area and enclosed volume. 1 Supplemental Materials (Not to be Published) #12;Supplemental Material by Quinn et al. 2 bending energy is given by Fbending = adjacent , pair
Dynamic procedure for filtered gyrokinetic simulations
Morel, P.; Banon Navarro, A.; Albrecht-Marc, M.; Carati, D. [Statistical and Plasma Physics Laboratory, Universite Libre de Bruxelles, Bruxelles 1050 (Belgium); Merz, F.; Goerler, T.; Jenko, F. [Max-Planck-Institut fuer Plasmaphysik, EURATOM Association, D-85748 Garching (Germany)
2012-01-15T23:59:59.000Z
Large eddy simulations (LES) of gyrokinetic plasma turbulence are investigated as interesting candidates to decrease the computational cost. A dynamic procedure is implemented in the gene code, allowing for dynamic optimization of the free parameters of the LES models (setting the amplitudes of dissipative terms). Employing such LES methods, one recovers the free energy and heat flux spectra obtained from highly resolved direct numerical simulations. Systematic comparisons are performed for different values of the temperature gradient and magnetic shear, parameters which are of prime importance in ion temperature gradient driven turbulence. Moreover, the degree of anisotropy of the problem, which can vary with parameters, can be adapted dynamically by the method that shows gyrokinetic large eddy simulation to be a serious candidate to reduce numerical cost of gyrokinetic solvers.
Eddy fluxes in baroclinic turbulence
Thompson, Andrew F.
2006-01-01T23:59:59.000Z
near-inertial energy in an eddying ocean channel model. Geo-dissipation of tidal energy in the deep ocean inferred fromfor the Southern Ocean), the rate of energy input by wind
Doyle, Martin
Excellence Center for Loudermilk Graham Memorial Daniels Hill Ackland McCaskill Paul Green Eddie Smith Alumni Carolina at Chapel Hill : 500 5000 Feet Student Life Classrooms Health Affairs Libraries Parking Decks
Low frequency eddy current benchmark study for model validation
Mooers, R. D.; Boehnlein, T. R. [University of Dayton Research Institute, Structural Integrity Division, Dayton, OH, 45469 (United States); Cherry, M. R.; Knopp, J. S. [Air Force Research Lab, NDE Division, Wright Patterson, OH 45433 (United States); Aldrin, J. C. [Computational Tools, Gurnee, IL 60031 (United States); Sabbagh, H. A. [Victor Technologies LLC, Bloomington, IN 47401 (United States)
2011-06-23T23:59:59.000Z
This paper presents results of an eddy current model validation study. Precise measurements were made using an impedance analyzer to investigate changes in impedance due to Electrical Discharge Machining (EDM) notches in aluminum plates. Each plate contained one EDM notch at an angle of 0, 10, 20, or 30 degrees from the normal of the plate surface. Measurements were made with the eddy current probe both scanning parallel and perpendicular to the notch length. The experimental response from the vertical and oblique notches will be reported and compared to results from different numerical simulation codes.
Turbulence Modelling and Stirring Mechanisms in the Cosmological Large-scale Structure
Iapichino, L; Niemeyer, J C; Merklein, J
2011-01-01T23:59:59.000Z
FEARLESS (Fluid mEchanics with Adaptively Refined Large Eddy SimulationS) is a numerical scheme for modelling subgrid-scale turbulence in cosmological adaptive mesh refinement simulations. In this contribution, the main features of this tool will be outlined. We discuss the application of this method to cosmological simulations of the large-scale structure. The simulations show that the production of turbulence has a different redshift dependence in the intra-cluster medium and the warm-hot intergalactic medium, caused by the distinct stirring mechanisms (mergers and shock interactions) acting in them. Some properties of the non-thermal pressure support in the two baryon phases are also described.
NV Energy Large-Scale Photovoltaic Integration Study: Intra-Hour Dispatch and AGC Simulation
Lu, Shuai; Etingov, Pavel V.; Meng, Da; Guo, Xinxin; Jin, Chunlian; Samaan, Nader A.
2013-01-02T23:59:59.000Z
The uncertainty and variability with photovoltaic (PV) generation make it very challenging to balance power system generation and load, especially under high penetration cases. Higher reserve requirements and more cycling of conventional generators are generally anticipated for large-scale PV integration. However, whether the existing generation fleet is flexible enough to handle the variations and how well the system can maintain its control performance are difficult to predict. The goal of this project is to develop a software program that can perform intra-hour dispatch and automatic generation control (AGC) simulation, by which the balancing operations of a system can be simulated to answer the questions posed above. The simulator, named Electric System Intra-Hour Operation Simulator (ESIOS), uses the NV Energy southern system as a study case, and models the system’s generator configurations, AGC functions, and operator actions to balance system generation and load. Actual dispatch of AGC generators and control performance under various PV penetration levels can be predicted by running ESIOS. With data about the load, generation, and generator characteristics, ESIOS can perform similar simulations and assess variable generation integration impacts for other systems as well. This report describes the design of the simulator and presents the study results showing the PV impacts on NV Energy real-time operations.
SSALMON - The Solar Simulations for the Atacama Large Millimeter Observatory Network
Wedemeyera, S; Brajsa, R; Barta, M; Hudson, H; Fleishman, G; Loukitcheva, M; Fleck, B; Kontar, E; De Pontieu, B; Tiwari, S; Kato, Y; Soler, R; Yagoubov, P; Black, J H; Antolin, P; Gunar, S; Labrosse, N; Benz, A O; Nindos, A; Steffen, M; Scullion, E; Doyle, J G; Zaqarashvili, T; Hanslmeier, A; Nakariakov, V M; Heinzel, P; Ayres, T; Karlicky, M
2015-01-01T23:59:59.000Z
The Solar Simulations for the Atacama Large Millimeter Observatory Network (SSALMON) was initiated in 2014 in connection with two ALMA development studies. The Atacama Large Millimeter/submillimeter Array (ALMA) is a powerful new tool, which can also observe the Sun at high spatial, temporal, and spectral resolution. The international SSALMONetwork aims at coordinating the further development of solar observing modes for ALMA and at promoting scientific opportunities for solar physics with particular focus on numerical simulations, which can provide important constraints for the observing modes and can aid the interpretation of future observations. The radiation detected by ALMA originates mostly in the solar chromosphere - a complex and dynamic layer between the photosphere and corona, which plays an important role in the transport of energy and matter and the heating of the outer layers of the solar atmosphere. Potential targets include active regions, prominences, quiet Sun regions, flares. Here, we give a...
Parametric instabilities of large-amplitude parallel propagating Alfven waves: 2-D PIC simulation
Yasuhiro Nariyuki; Shuichi Matsukiyo; Tohru Hada
2008-04-25T23:59:59.000Z
We discuss the parametric instabilities of large-amplitude parallel propagating Alfven waves using the 2-D PIC simulation code. First, we confirmed the results in the past study [Sakai et al, 2005] that the electrons are heated due to the modified two stream instability and that the ions are heated by the parallel propagating ion acoustic waves. However, although the past study argued that such parallel propagating longitudinal waves are excited by transverse modulation of parent Alfven wave, we consider these waves are more likely to be generated by the usual, parallel decay instability. Further, we performed other simulation runs with different polarization of the parent Alfven waves or the different ion thermal velocity. Numerical results suggest that the electron heating by the modified two stream instability due to the large amplitude Alfven waves is unimportant with most parameter sets.
Energy Spectra of Quantum Turbulence: Large-scale Simulation and Modeling
Machida, Masahiko; Kano, Takuma; L'vov, Victor S; Rudenko, Oleksii; Tsubota, Makoto
2010-01-01T23:59:59.000Z
In 2048^3 simulation of quantum turbulence within the Gross-Pitaevskii equation we demonstrate that the large scale motions have a classical Kolmogorov-1941 energy spectrum E(k) ~ k^{-5/3}, followed by an energy accumulation with E(k) ~ const at 1/k about the mean intervortex distance. This behavior was predicted by the L'vov-Nazarenko-Rudenko bottleneck model [Phys.Rev.B 76, 024520 (2007)], further developed in the Letter.
Seabird associations with mesoscale eddies: the subtropical Indian Ocean
Hyrenbach, KD; Veit, RR; Weimerskirch, H; Jr, HGL
2006-01-01T23:59:59.000Z
Seabird associations with mesoscale eddies: the subtropicalsur- hydrographic fronts and mesoscale eddies (Haney & veyedclimatologies. J Clim mesoscale variability across ocean
Papadopoulos, Christos
135 Chapter 6 LMS IMPLEMENTATION In the previous chapter we used simulation to evaluate the performance of LMS in large, sim- ulated topologies. The simulations showed that LMS performs very well complement our simulation by describing the implementation and evaluation of LMS in the kernel of a real
Papadopoulos, Christos
135 Chapter 6 LMS IMPLEMENTATION In the previous chapter we used simulation to evaluate the performance of LMS in large, sim ulated topologies. The simulations showed that LMS performs very well complement our simulation by describing the implementation and evaluation of LMS in the kernel of a real
Copy of Using Emulation and Simulation to Understand the Large-Scale Behavior of the Internet.
Adalsteinsson, Helgi; Armstrong, Robert C.; Chiang, Ken; Gentile, Ann C. [Sandia National Laboratories, Albuquerque, NM; Lloyd, Levi; Minnich, Ronald G.; Vanderveen, Keith; Van Randwyk, Jamie A; Rudish, Don W.
2008-10-01T23:59:59.000Z
We report on the work done in the late-start LDRDUsing Emulation and Simulation toUnderstand the Large-Scale Behavior of the Internet. We describe the creation of a researchplatform that emulates many thousands of machines to be used for the study of large-scale inter-net behavior. We describe a proof-of-concept simple attack we performed in this environment.We describe the successful capture of a Storm bot and, from the study of the bot and furtherliterature search, establish large-scale aspects we seek to understand via emulation of Storm onour research platform in possible follow-on work. Finally, we discuss possible future work.3
Simulations and measurements of beam loss patterns at the CERN Large Hadron Collider
R. Bruce; R. W. Assmann; V. Boccone; C. Bracco; M. Brugger; M. Cauchi; F. Cerutti; D. Deboy; A. Ferrari; L. Lari; A. Marsili; A. Mereghetti; D. Mirarchi; E. Quaranta; S. Redaelli; G. Robert-Demolaize; A. Rossi; B. Salvachua; E. Skordis; C. Tambasco; G. Valentino; T. Weiler; V. Vlachoudis; D. Wollmann
2014-09-10T23:59:59.000Z
The CERN Large Hadron Collider (LHC) is designed to collide proton beams of unprecedented energy, in order to extend the frontiers of high-energy particle physics. During the first very successful running period in 2010--2013, the LHC was routinely storing protons at 3.5--4 TeV with a total beam energy of up to 146 MJ, and even higher stored energies are foreseen in the future. This puts extraordinary demands on the control of beam losses. An un-controlled loss of even a tiny fraction of the beam could cause a superconducting magnet to undergo a transition into a normal-conducting state, or in the worst case cause material damage. Hence a multi-stage collimation system has been installed in order to safely intercept high-amplitude beam protons before they are lost elsewhere. To guarantee adequate protection from the collimators, a detailed theoretical understanding is needed. This article presents results of numerical simulations of the distribution of beam losses around the LHC that have leaked out of the collimation system. The studies include tracking of protons through the fields of more than 5000 magnets in the 27 km LHC ring over hundreds of revolutions, and Monte-Carlo simulations of particle-matter interactions both in collimators and machine elements being hit by escaping particles. The simulation results agree typically within a factor 2 with measurements of beam loss distributions from the previous LHC run. Considering the complex simulation, which must account for a very large number of unknown imperfections, and in view of the total losses around the ring spanning over 7 orders of magnitude, we consider this an excellent agreement. Our results give confidence in the simulation tools, which are used also for the design of future accelerators.
Eddy current scanning at Fermilab
Boffo, C.; Bauer, P.; Foley, M.; /Fermilab; Brinkmann, A.; /DESY; Ozelis, J.; /Jefferson Lab
2005-07-01T23:59:59.000Z
In the framework of SRF cavity development, Fermilab is creating the infrastructure needed for the characterization of the material used in the cavity fabrication. An important step in the characterization of ''as received'' niobium sheets is the eddy current scanning. Eddy current scanning is a non-destructive technique first adopted and further developed by DESY with the purpose of checking the cavity material for sub-surface defects and inclusions. Fermilab has received and further upgraded a commercial eddy current scanner previously used for the SNS project. The upgrading process included developing new filtering software. This scanner is now used daily to scan the niobium sheets for the Fermilab third harmonic and transverse deflecting cavities. This paper gives a status report on the scanning results obtained so far, including a discussion of the typology of signals being detected. We also report on the efforts to calibrate this scanner, a work conducted in collaboration with DESY.
Calculation of Eddy Currents In the CTH Vacuum Vessel and Coil Frame
A. Zolfaghari, A. Brooks, A. Michaels, J. Hanson, and G. Hartwell
2012-09-25T23:59:59.000Z
Knowledge of eddy currents in the vacuum vessel walls and nearby conducting support structures can significantly contribute to the accuracy of Magnetohydrodynamics (MHD) equilibrium reconstruction in toroidal plasmas. Moreover, the magnetic fields produced by the eddy currents could generate error fields that may give rise to islands at rational surfaces or cause field lines to become chaotic. In the Compact Toroidal Hybrid (CTH) device (R0 = 0.75 m, a = 0.29 m, B ? 0.7 T), the primary driver of the eddy currents during the plasma discharge is the changing flux of the ohmic heating transformer. Electromagnetic simulations are used to calculate eddy current paths and profile in the vacuum vessel and in the coil frame pieces with known time dependent currents in the ohmic heating coils. MAXWELL and SPARK codes were used for the Electromagnetic modeling and simulation. MAXWELL code was used for detailed 3D finite-element analysis of the eddy currents in the structures. SPARK code was used to calculate the eddy currents in the structures as modeled with shell/surface elements, with each element representing a current loop. In both cases current filaments representing the eddy currents were prepared for input into VMEC code for MHD equilibrium reconstruction of the plasma discharge. __________________________________________________
Nicoud, Franck
walls is an important phenomenon in combustion chambers and a main design constraint in gas turbines temperatures and heat fluxes, is a key issue in combustion (Lakshminarayana, 1996; Lefebvre, 1999; Schiele. After combustion, the interaction of the hot burnt gases with the high pressure stator and the first
Expert system for analyzing eddy current measurements
Levy, Arthur J. (Schenectady, NY); Oppenlander, Jane E. (Scotia, NY); Brudnoy, David M. (Albany, NY); Englund, James M. (Clifton Park, NY); Loomis, Kent C. (Clifton Park, NY)
1994-01-01T23:59:59.000Z
A method and apparatus (called DODGER) analyzes eddy current data for heat exchanger tubes or any other metallic object. DODGER uses an expert system to analyze eddy current data by reasoning with uncertainty and pattern recognition. The expert system permits DODGER to analyze eddy current data intelligently, and obviate operator uncertainty by analyzing the data in a uniform and consistent manner.
Large-scale simulation of methane dissociation along the West Spitzbergen Margin
Reagan, M.T.; Moridis, G.J.
2009-07-15T23:59:59.000Z
Vast quantities of methane are trapped in oceanic hydrate deposits, and there is concern that a rise in the ocean temperature will induce dissociation of these hydrate accumulations, potentially releasing large amounts of methane into the atmosphere. The recent discovery of active methane gas venting along the landward limit of the gas hydrate stability zone (GHSZ) on the shallow continental slope west of Spitsbergen could be an indication of this process, if the source of the methane can be confidently attributed to dissociating hydrates. In the first large-scale simulation study of its kind, we simulate shallow hydrate dissociation in conditions representative of the West Spitsbergen margin to test the hypothesis that the observed gas release originated from hydrates. The simulation results are consistent with this hypothesis, and are in remarkable agreement with the recently published observations. They show that shallow, low-saturation hydrate deposits, when subjected to temperature increases at the seafloor, can release significant quantities of methane, and that the releases will be localized near the landward limit of the top of the GHSZ. These results indicate the possibility that hydrate dissociation and methane release may be both a consequence and a cause of climate change.
Shay I. Heizler; David A. Kessler
2015-05-18T23:59:59.000Z
We study the high-velocity regime mode-I fracture instability when small microbranches start to appear near the main crack, using large scale simulations. Some of the features of those microbranches have been reproduced qualitatively in smaller scale studies (using ${\\cal O}(10^4)$ atoms) on both a model of an amorphous materials (via the continuous random network model) and using perturbed lattice models. In this study, larger scale simulations (${\\cal O}(10^6)$ atoms) were performed using multi-threading computing on a GPU device, in order to achieve more physically realistic results. First, we find that the microbranching pattern appears to be converging with the lattice width. Second, the simulations reproduce the growth of the size of a microbranch as a function of the crack velocity, as well as the increase of the amplitude of the derivative of the electrical resistance RMS with respect to the time as a function of the crack velocity. In addition, the simulations yield the correct branching angle of the microbranches, and the power law governing the shape of the microbranches seems to be lower than one, so that the side cracks turn over in the direction of propagation of the main crack as seen in experiment.
MEASUREMENTS AND MODELING OF EDDY CURRENT EFFECTS IN BNL'S AGS BOOSTER.
BROWN, K.A.; AHRENS, L.; GARDNER, C.; GLENN, J.W.; HARVEY, M.; MENG, W.; ZENO, K.
2006-06-23T23:59:59.000Z
Recent beam experiments at BNL's AGS Booster have enabled us to study in more detail the effects of eddy currents on the lattice structure and our control over the betatron tune. The Booster is capable of operating at ramp rates as high as 9 T/sec. At these ramp rates eddy currents in the vacuum chambers significantly alter the fields and gradients seen by the beam as it is accelerated. The Booster was designed with these effects in mind and to help control the field uniformity and linearity in the Booster Dipoles special vacuum chambers were designed with current windings to negate the affect of the induced eddy currents. In this report results from betatron tune measurements and eddy current simulations will be presented. We will then present results from modeling the accelerator using the results of the magnetic field simulations and compare these to the measurements.
2004-01-01T23:59:59.000Z
Mathematics and Computers in Simulation 65 (2004) 557577 Parallel runs of a large air pollution 20 January 2004; accepted 21 January 2004 Abstract Large-scale air pollution models can successfully. The mathematical description of a large-scale air pollution model will be discussed in this paper. The principles
Chakravarty, A.; Emanuel, A.S.; Bernath, J.A. [Chevron Petroleum Technology Company, LaHabra, CA (United States)
1997-08-01T23:59:59.000Z
The application of streamtube models for reservoir simulation has an extensive history in the oil industry. Although these models are strictly applicable only to fields under voidage balance, they have proved to be useful in a large number of fields provided that there is no solution gas evolution and production. These models combine the benefit of very fast computational time with the practical ability to model a large reservoir over the course of its history. These models do not, however, directly incorporate the detailed geological information that recent experience has taught is important. This paper presents a technique for mapping the saturation information contained in a history matched streamtube model onto a detailed geostatistically derived finite difference grid. With this technique, the saturation information in a streamtube model, data that is actually statistical in nature, can be identified with actual physical locations in a field and a picture of the remaining oil saturation can be determined. Alternatively, the streamtube model can be used to simulate the early development history of a field and the saturation data then used to initialize detailed late time finite difference models. The proposed method is presented through an example application to the Ninian reservoir. This reservoir, located in the North Sea (UK), is a heterogeneous sandstone characterized by a line drive waterflood, with about 160 wells, and a 16 year history. The reservoir was satisfactorily history matched and mapped for remaining oil saturation. A comparison to 3-D seismic survey and recently drilled wells have provided preliminary verification.
Figueroa, Aldo [Facultad de Ciencias, Universidad Autónoma del Estado de Morelos, Cuernavaca, Morelos 62209 (Mexico)] [Facultad de Ciencias, Universidad Autónoma del Estado de Morelos, Cuernavaca, Morelos 62209 (Mexico); Meunier, Patrice; Villermaux, Emmanuel [Aix-Marseille Univ., CNRS, Centrale Marseille, IRPHE, Marseille F-13384 (France)] [Aix-Marseille Univ., CNRS, Centrale Marseille, IRPHE, Marseille F-13384 (France); Cuevas, Sergio; Ramos, Eduardo [Instituto de Energías Renovables, Universidad Nacional Autónoma de México, A.P. 34, Temixco, Morelos 62580 (Mexico)] [Instituto de Energías Renovables, Universidad Nacional Autónoma de México, A.P. 34, Temixco, Morelos 62580 (Mexico)
2014-01-15T23:59:59.000Z
We present a combination of experiment, theory, and modelling on laminar mixing at large Péclet number. The flow is produced by oscillating electromagnetic forces in a thin electrolytic fluid layer, leading to oscillating dipoles, quadrupoles, octopoles, and disordered flows. The numerical simulations are based on the Diffusive Strip Method (DSM) which was recently introduced (P. Meunier and E. Villermaux, “The diffusive strip method for scalar mixing in two-dimensions,” J. Fluid Mech. 662, 134–172 (2010)) to solve the advection-diffusion problem by combining Lagrangian techniques and theoretical modelling of the diffusion. Numerical simulations obtained with the DSM are in reasonable agreement with quantitative dye visualization experiments of the scalar fields. A theoretical model based on log-normal Probability Density Functions (PDFs) of stretching factors, characteristic of homogeneous turbulence in the Batchelor regime, allows to predict the PDFs of scalar in agreement with numerical and experimental results. This model also indicates that the PDFs of scalar are asymptotically close to log-normal at late stages, except for the large concentration levels which correspond to low stretching factors.
Homogeneous SPC/E water nucleation in large molecular dynamics simulations
Angelil, R; Tanaka, K; Tanaka, H
2015-01-01T23:59:59.000Z
We perform direct large molecular dynamics simulations of homogeneous SPC/E water nucleation, using up to $\\sim 4\\cdot 10^6$ molecules. Our large system sizes allow us to measure extremely low and accurate nucleation rates, down to $\\sim 10^{19}\\,\\textrm{cm}^{-3}\\textrm{s}^{-1}$, helping close the gap between experimentally measured rates $\\sim 10^{17}\\,\\textrm{cm}^{-3}\\textrm{s}^{-1}$. We are also able to precisely measure size distributions, sticking efficiencies, cluster temperatures, and cluster internal densities. We introduce a new functional form to implement the Yasuoka-Matsumoto nucleation rate measurement technique (threshold method). Comparison to nucleation models shows that classical nucleation theory over-estimates nucleation rates by a few orders of magnitude. The semi-phenomenological nucleation model does better, under-predicting rates by at worst, a factor of 24. Unlike what has been observed in Lennard-Jones simulations, post-critical clusters have temperatures consistent with the run avera...
A numerical model of aerosol scavenging. Part 2, Simulation of a large city fire
Bradley, M.M.; Molenkamp, C.R.
1991-10-01T23:59:59.000Z
Using a three-dimensional numerical cloud/smoke-plume model, we have simulated the burning of a large, mid-latitude city following a nuclear exchange. The model includes 18 dynamic and microphysical equations that predict the fire-driven airflow, cloud processes, and smoke-cloud interactions. In the simulation, the intense heating from the burning city produces a firestorm with updraft velocities exceeding 60 m/s. Within 15 minutes of ignition, the smoke plume penetrates the tropopause. The updraft triggers a cumulonimbus cloud that produces significant quantities of ice, snow, and hail. These solid hydrometeors, as well as cloud droplets and rain, interact with the smoke particles from the fire. At the end of the one-hour simulation, over 20% of the smoke is in slowly falling snowflakes. If the snow reaches the ground before the flakes completely sublimate (or melt and then evaporate), then only approximately 50% of the smoke will survive the scavenging processes and remain in the atmosphere to affect the global climate.
A Metascalable Computing Framework for Large Spatiotemporal-Scale Atomistic Simulations
Nomura, K; Seymour, R; Wang, W; Kalia, R; Nakano, A; Vashishta, P; Shimojo, F; Yang, L H
2009-02-17T23:59:59.000Z
A metascalable (or 'design once, scale on new architectures') parallel computing framework has been developed for large spatiotemporal-scale atomistic simulations of materials based on spatiotemporal data locality principles, which is expected to scale on emerging multipetaflops architectures. The framework consists of: (1) an embedded divide-and-conquer (EDC) algorithmic framework based on spatial locality to design linear-scaling algorithms for high complexity problems; (2) a space-time-ensemble parallel (STEP) approach based on temporal locality to predict long-time dynamics, while introducing multiple parallelization axes; and (3) a tunable hierarchical cellular decomposition (HCD) parallelization framework to map these O(N) algorithms onto a multicore cluster based on hybrid implementation combining message passing and critical section-free multithreading. The EDC-STEP-HCD framework exposes maximal concurrency and data locality, thereby achieving: (1) inter-node parallel efficiency well over 0.95 for 218 billion-atom molecular-dynamics and 1.68 trillion electronic-degrees-of-freedom quantum-mechanical simulations on 212,992 IBM BlueGene/L processors (superscalability); (2) high intra-node, multithreading parallel efficiency (nanoscalability); and (3) nearly perfect time/ensemble parallel efficiency (eon-scalability). The spatiotemporal scale covered by MD simulation on a sustained petaflops computer per day (i.e. petaflops {center_dot} day of computing) is estimated as NT = 2.14 (e.g. N = 2.14 million atoms for T = 1 microseconds).
Process Design by FEM Simulation for Shape Ring Rolling of Large-Sized Ring
Lee, Y. S.; Lee, M. W. [Materials Deformation Group, Korea Institute of Materials Science.531 Changwondaero, Changwon, Gyeongsangnam 641-831 (Korea, Republic of); Park, S. S.; Lee, I. [Forging Production Division, Unison Co., Ltd. 1984, Chojeon-Ri, Sanam-Myeon, Sacheon-Si, Gyeongsangnam-Do (Korea, Republic of); Moon, Y. H. [Engineering Research Center for Net Shape and Die Manufacturing, Pusan National University, 30 Jangeon-dong, Geumjeong-gu, Busan 609-735 (Korea, Republic of)
2010-06-15T23:59:59.000Z
Ring rolling process is usually used to fabricate large-sized ring, such as, tower flange for wind power electric generator. Many kinds of seamless ring are used in wind power electric generator and manufactured by ring rolling process. In general, final part is machined after forming with shape of plain square section. Since interests for near net shaping of seamless ring have been increased gradually because of green energy, it is necessary to develop the technology for shape ring rolling with respect to the market demands and cost. Therefore, we studied the process and die design for shape ring rolling of large sized ring over 3,500 mm out diameter by experiment and FEM simulation. Ring rolling process is very difficult to solve by FEM method because of equilibrium state and size effect, etc. Moreover, shape ring rolling is more difficult to solve the problem that two plastic deformation zones are different each other, that is main roll and conical roll. Also since conical roll has a shape, deformation velocity field is very much complex and the deformed section passed axial roll is different section and velocity field. The FE simulations are performed to analyze process variables affected in forming of profiled ring. Therefore, the main features of used FE model are: (1) it adopts a transient or unsteady state full ring mesh to model the deformation processes and shape development; (2) the mandrel and conical rolls are modeled using coupled heat-transfer elements; (3) the model involves the full process from blank through perform to final profiled ring. From these calculated results, we have proposed the mechanisms of various tools, such as mandrel and conical roll. The calculated results are compared experimental results. Calculated results can predict the tilting of profiled ring and then process variables to form large sized ring.
Effects of winds and Caribbean eddies on the frequency of Loop Current eddy shedding: A numerical of Mexico, Caribbean Current, Loop Current, eddy shedding, winds and eddies, numerical ocean model Citation of Loop Current eddy shedding: A numerical model study, J. Geophys. Res., 108(C10), 3324, doi:10
Large-scale Nanostructure Simulations from X-ray Scattering Data On Graphics Processor Clusters
Sarje, Abhinav; Pien, Jack; Li, Xiaoye; Chan, Elaine; Chourou, Slim; Hexemer, Alexander; Scholz, Arthur; Kramer, Edward
2012-01-15T23:59:59.000Z
X-ray scattering is a valuable tool for measuring the structural properties of materialsused in the design and fabrication of energy-relevant nanodevices (e.g., photovoltaic, energy storage, battery, fuel, and carbon capture andsequestration devices) that are key to the reduction of carbon emissions. Although today's ultra-fast X-ray scattering detectors can provide tremendousinformation on the structural properties of materials, a primary challenge remains in the analyses of the resulting data. We are developing novelhigh-performance computing algorithms, codes, and software tools for the analyses of X-ray scattering data. In this paper we describe two such HPCalgorithm advances. Firstly, we have implemented a flexible and highly efficient Grazing Incidence Small Angle Scattering (GISAXS) simulation code based on theDistorted Wave Born Approximation (DWBA) theory with C++/CUDA/MPI on a cluster of GPUs. Our code can compute the scattered light intensity from any givensample in all directions of space; thus allowing full construction of the GISAXS pattern. Preliminary tests on a single GPU show speedups over 125x compared tothe sequential code, and almost linear speedup when executing across a GPU cluster with 42 nodes, resulting in an additional 40x speedup compared to usingone GPU node. Secondly, for the structural fitting problems in inverse modeling, we have implemented a Reverse Monte Carlo simulation algorithm with C++/CUDAusing one GPU. Since there are large numbers of parameters for fitting in the in X-ray scattering simulation model, the earlier single CPU code required weeks ofruntime. Deploying the AccelerEyes Jacket/Matlab wrapper to use GPU gave around 100x speedup over the pure CPU code. Our further C++/CUDA optimization deliveredan additional 9x speedup.
Shrestha, Som S [ORNL] [ORNL; Miller, William A [ORNL] [ORNL; Desjarlais, Andre Omer [ORNL] [ORNL
2013-01-01T23:59:59.000Z
Application of radiant barriers and low-emittance surface coatings in residential building attics can significantly reduce conditioning loads from heat flow through attic floors. The roofing industry has been developing and using various radiant barrier systems and low-emittance surface coatings to increase energy efficiency in buildings; however, minimal data are available that quantifies the effectiveness of these technologies. This study evaluates performance of various attic radiant barrier systems under simulated summer daytime conditions and nighttime or low solar gain daytime winter conditions using the large scale climate simulator (LSCS). The four attic configurations that were evaluated are 1) no radiant barrier (control), 2) perforated low-e foil laminated oriented strand board (OSB) deck, 3) low-e foil stapled on rafters, and 4) liquid applied low-emittance coating on roof deck and rafters. All test attics used nominal RUS 13 h-ft2- F/Btu (RSI 2.29 m2-K/W) fiberglass batt insulation on attic floor. Results indicate that the three systems with radiant barriers had heat flows through the attic floor during summer daytime condition that were 33%, 50%, and 19% lower than the control, respectively.
W. Schmidt; J. C. Niemeyer; W. Hillebrandt
2006-01-23T23:59:59.000Z
We present a one-equation subgrid scale model that evolves the turbulence energy corresponding to unresolved velocity fluctuations in large eddy simulations. The model is derived in the context of the Germano consistent decomposition of the hydrodynamical equations. The eddy-viscosity closure for the rate of energy transfer from resolved toward subgrid scales is localised by means of a dynamical procedure for the computation of the closure parameter. Therefore, the subgrid scale model applies to arbitrary flow geometry and evolution. For the treatment of microscopic viscous dissipation a semi-statistical approach is used, and the gradient-diffusion hypothesis is adopted for turbulent transport. A priori tests of the localised eddy-viscosity closure and the gradient-diffusion closure are made by analysing data from direct numerical simulations. As an a posteriori testing case, the large eddy simulation of thermonuclear combustion in forced isotropic turbulence is discussed. We intend the formulation of the subgrid scale model in this paper as a basis for more advanced applications in numerical simulations of complex astrophysical phenomena involving turbulence.
Eddy mean flow decomposition and eddy diffusivity estimates in the tropical Pacific Ocean
Eddy mean flow decomposition and eddy diffusivity estimates in the tropical Pacific Ocean: 2] Eddy diffusivity of the surface velocity field in the tropical Pacific Ocean was estimated using diffusivity estimates in the tropical Pacific Ocean: 2. Results, J. Geophys. Res., 107(C10), 3154, doi:10
Polak, S.J.; van Welij, J.S.; Wachters, A.J.H.
1983-11-01T23:59:59.000Z
This paper presents a new EDDY current model. This model minimizes the number of unknown per point. The authors also discuss the uniqueness aspects involved.
Master Thesis Proposal Eddy Current Imaging of Electrically Conducting Media
Vuik, Kees
Master Thesis Proposal Eddy Current Imaging of Electrically Conducting Media Domenico Lahaye and optimization techniques en- abling the eddy current imaging of electrically conducting media. Examples: · perform a literature study into topics such as eddy current imaging, inverse problems including
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)41clothThe Bonneville PowerTariff Pages default Sign In AboutIsrelocates IBreakingBurns,Rusty GrayEnergyStochasticLarge
Lagrangian study of transport and mixing in a mesoscale eddy street
Prants, S V; Ponomarev, V I; Uleysky, M Yu; 10.1016/j.ocemod.2011.02.008
2012-01-01T23:59:59.000Z
We use dynamical systems approach and Lagrangian tools to study surface transport and mixing of water masses in a selected coastal region of the Japan Sea with moving mesoscale eddies associated with the Primorskoye Current. Lagrangian trajectories are computed for a large number of particles in an interpolated velocity field generated by a numerical regional multi-layer eddy-resolving circulation model. We compute finite-time Lyapunov exponents for a comparatively long period of time by the method developed and plot the Lyapunov synoptic map quantifying surface transport and mixing in that region. This map uncovers the striking flow structures along the coast with a mesoscale eddy street and repelling material lines. We propose new Lagrangian diagnostic tools --- the time of exit of particles off a selected box, the number of changes of the sign of zonal and meridional velocities --- to study transport and mixing by a pair of strongly interacting eddies often visible at sea-surface temperature satellite imag...
Eddy Correlation Systems Receive Upgrade
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)41clothThe Bonneville Power AdministrationHawaii Electricity Profile 2013callYear 1 Winners Announced!TriCoatings2 Eddy
Profile hidden Markov models Sean R. Eddy
Eddy, Sean
Profile hidden Markov models Sean R. Eddy Dept. of Genetics, Washington University School of Medicine 4566 Scott Ave., St. Louis MO 63110 USA eddy@genetics.wustl.edu keywords: profiles, hidden Markov models, protein families Abstract Summary: I review the recent literature on profile hid den Markov
A Report on Simulation-Driven Reliability and Failure Analysis of Large-Scale Storage Systems
Wan, Lipeng [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Wang, Feiyi [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Oral, H. Sarp [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Vazhkudai, Sudharshan S. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Cao, Qing [Univ. of Tennessee, Knoxville, TN (United States)
2014-11-01T23:59:59.000Z
High-performance computing (HPC) storage systems provide data availability and reliability using various hardware and software fault tolerance techniques. Usually, reliability and availability are calculated at the subsystem or component level using limited metrics such as, mean time to failure (MTTF) or mean time to data loss (MTTDL). This often means settling on simple and disconnected failure models (such as exponential failure rate) to achieve tractable and close-formed solutions. However, such models have been shown to be insufficient in assessing end-to-end storage system reliability and availability. We propose a generic simulation framework aimed at analyzing the reliability and availability of storage systems at scale, and investigating what-if scenarios. The framework is designed for an end-to-end storage system, accommodating the various components and subsystems, their interconnections, failure patterns and propagation, and performs dependency analysis to capture a wide-range of failure cases. We evaluate the framework against a large-scale storage system that is in production and analyze its failure projections toward and beyond the end of lifecycle. We also examine the potential operational impact by studying how different types of components affect the overall system reliability and availability, and present the preliminary results
Penner, J.E.; Haselman L. Jr.; Edwards, L.L.
1986-10-01T23:59:59.000Z
Smoke from raging fires produced in the aftermath of a major nuclear exchange has been predicted to cause large decreases in surface temperatures. However, the extent of the decrease and even the sign of the temperature change depend on how the smoke is distributed with altitude. We present a model capable of evaluating the initial distribution of lofted smoke above a massive fire. Calculations are shown for a two-dimensional slab version of the model and a full three-dimensional version. The model has been evaluated by simulating smoke heights for the Hamburg firestorm of 1943, and a smaller-scale oil fire which occurred in Long Beach in 1958. Our plume heights for these fires are compared to those predicted by the classical Morton-Taylor-Turner theory for weakly buoyant plumes. We consider the effect of the added buoyancy caused by condensation of waterladen ground level air being carried to high altitude with the convection column, as well as the effects of background wind on the calculated smoke plume heights for several fire intensities. We find that the rise height of the plume depends on the assumed background atmospheric conditions, as well as the fire intensity.
Simulations and measurements of beam loss patterns at the CERN Large Hadron Collider
Bruce, R; Boccone, V; Bracco, C; Brugger, M; Cauchi, M; Cerutti, F; Deboy, D; Ferrari, A; Lari, L; Marsili, A; Mereghetti, A; Mirarchi, D; Quaranta, E; Redaelli, S; Robert-Demolaize, G; Rossi, A; Salvachua, B; Skordis, E; Tambasco, C; Valentino, G; Weiler, T; Vlachoudis, V; Wollmann, D
2014-01-01T23:59:59.000Z
The CERN Large Hadron Collider (LHC) is designed to collide proton beams of unprecedented energy, in order to extend the frontiers of high-energy particle physics. During the first very successful running period in 2010--2013, the LHC was routinely storing protons at 3.5--4 TeV with a total beam energy of up to 146 MJ, and even higher stored energies are foreseen in the future. This puts extraordinary demands on the control of beam losses. An un-controlled loss of even a tiny fraction of the beam could cause a superconducting magnet to undergo a transition into a normal-conducting state, or in the worst case cause material damage. Hence a multi-stage collimation system has been installed in order to safely intercept high-amplitude beam protons before they are lost elsewhere. To guarantee adequate protection from the collimators, a detailed theoretical understanding is needed. This article presents results of numerical simulations of the distribution of beam losses around the LHC that have leaked out of the co...
An Efficient Priority Queue for Large FPGA-Based Discrete Event Simulations of
Herbordt, Martin
: Molecular dynamics simulation based on discrete event simulation (DMD) is emerging as an alternative to time Laboratory Department of Electrical and Computer Engineering Boston University; Boston, MA 02215 Abstract
Large-scale simulation of methane dissociation along the West Spitzbergen Margin
Reagan, M.T.
2010-01-01T23:59:59.000Z
and stability of gas hydrate-related bottom-simulatingPotential effects of gas hydrate on human welfare, Proc.simulated domain, extent of gas hydrate stability zone, and
Computer Energy Modeling Techniques for Simulation Large Scale Correctional Institutes in Texas
Heneghan, T.; Haberl, J. S.; Saman, N.; Bou-Saada, T. E.
1996-01-01T23:59:59.000Z
building enegy simulation program (LBL 1980; 1981; 1982; 1989; 1994). The second part of the project included evaluating the energy consumption of this prototype unit. This paper presents a methodology that may be used to view and improve simulation.... The DOE-2 Simulation Promam The DOE-2 hourly simulation program is composed of four sub-programs: LOADS, SYSTEMS, PLANT, and ECONOMICS (LBL 198 1). Figure 3 (LBL 1980) provides an overview of the DOE-2 program and shows the three general inputs...
Subsurface Defect Detection in Metals with Pulsed Eddy Current
Plotnikov, Yuri A. [GE Global Research Center, One Research Circle, Niskayuna, NY 12309-1135 (United States); Bantz, Walter J. [GE Aircraft Engines M and QTD, 10270 St. Rita Lane, Cincinnati, OH 45215 (United States)
2005-04-09T23:59:59.000Z
The eddy current (EC) method is traditionally used for open surface crack detection in metallic components. Subsurface voids in bulk metals can also be detected by the eddy current devices. Taking into consideration the skin effect in conductive materials, a lower frequency of electromagnetic excitation is used for a deeper penetration. A set of special specimens was designed and fabricated to investigate sensitivity to subsurface voids. Typically, flat bottom holes (FBHs) are used for subsurface defect simulation. This approach is not very representative of real defects for eddy current inspection because the FBH depth extends to the bottom of the specimen. Two-layer specimens with finite depth FBHs were fabricated and scanned with conventional EC of variable frequency. Sensitivity and spatial resolution of EC diminish with flaw depth. The pulsed EC approach was applied for flaw detection at variable distance under the surface. The transient response from multi-layer model was derived and compared to experiments. The multi-frequency nature of pulsed excitation provides effective coverage of a thick layer of material in one pass. Challenging aspects of subsurface flaw detection and visualization using the EC technique are discussed.
Lagrangian study of transport and mixing in a mesoscale eddy street
S. V. Prants; M. V. Budyansky; V. I. Ponomarev; M. Yu. Uleysky
2012-02-02T23:59:59.000Z
We use dynamical systems approach and Lagrangian tools to study surface transport and mixing of water masses in a selected coastal region of the Japan Sea with moving mesoscale eddies associated with the Primorskoye Current. Lagrangian trajectories are computed for a large number of particles in an interpolated velocity field generated by a numerical regional multi-layer eddy-resolving circulation model. We compute finite-time Lyapunov exponents for a comparatively long period of time by the method developed and plot the Lyapunov synoptic map quantifying surface transport and mixing in that region. This map uncovers the striking flow structures along the coast with a mesoscale eddy street and repelling material lines. We propose new Lagrangian diagnostic tools --- the time of exit of particles off a selected box, the number of changes of the sign of zonal and meridional velocities --- to study transport and mixing by a pair of strongly interacting eddies often visible at sea-surface temperature satellite images in that region. We develop a technique to track evolution of clusters of particles, streaklines and material lines. The Lagrangian tools used allow us to reveal mesoscale eddies and their structure, to track different phases of the coastal flow, to find inhomogeneous character of transport and mixing on mesoscales and submesoscales and to quantify mixing by the values of exit times and the number of times particles wind around the eddy's center.
Dynamics of the terrestrial planets from a large number of N-body simulations"! Rebecca A. Fischer1,
! 1 Dynamics of the terrestrial planets from a large number of N-body simulations"! #! Rebecca A and planetesimals was the final stage of""! terrestrial planet formation. This process is modeled using N of planetary#&! accretion as particular accretion pathways may be representative of a given dynamic#'! scenario
Reduced-Order Models of Zero-Net Mass-Flux Jets for Large-Scale Flow Control Simulations
Mittal, Rajat
Reduced-Order Models of Zero-Net Mass-Flux Jets for Large-Scale Flow Control Simulations Reni Raju computational tools are well suited for modeling the dynamics of zero-net mass-flux actuators, the computational vorticity, (s-1 ) I. Introduction ERO-net mass-flux (ZNMF) actuators or "synthetic jets" have potential
Oak Ridge National Laboratory
Envelope 1. Large Scale Climate Simulator (Building 3144) The LSCS tests roof and/or attic assemblies weighing up to 9000 kg (10 tons) and as high as 1.83 m (6 ft.) under any inhabited climatic and outdoors but also captures a wide range of secondary metrics. 2. Rotatable Guarded Hot Box (Building 3144
Chen, Q.
simulation models for chilled water and heating hot water distribution systems. The simulation model was used in a $2.3 million Ross Street chilled water pipe replacement project at Texas A&M University. A second project conducted at the University... of Texas at San Antonio was used as an example to demonstrate how to identify and design an optimal distribution system by using a simulation model. The author found that the minor losses of these closed loop thermal distribution systems...
Eddy current technique for predicting burst pressure
Petri, Mark C. (Yorkville, IL); Kupperman, David S. (Oak Park, IL); Morman, James A. (Woodridge, IL); Reifman, Jaques (Western Springs, IL); Wei, Thomas Y. C. (Downers Grove, IL)
2003-01-01T23:59:59.000Z
A signal processing technique which correlates eddy current inspection data from a tube having a critical tubing defect with a range of predicted burst pressures for the tube is provided. The method can directly correlate the raw eddy current inspection data representing the critical tubing defect with the range of burst pressures using a regression technique, preferably an artificial neural network. Alternatively, the technique deconvolves the raw eddy current inspection data into a set of undistorted signals, each of which represents a separate defect of the tube. The undistorted defect signal which represents the critical tubing defect is related to a range of burst pressures utilizing a regression technique.
Rotating concave eddy current probe
Roach, Dennis P. (Albuquerque, NM); Walkington, Phil (Albuquerque, NM); Rackow, Kirk A. (Albuquerque, NM); Hohman, Ed (Albuquerque, NM)
2008-04-01T23:59:59.000Z
A rotating concave eddy current probe for detecting fatigue cracks hidden from view underneath the head of a raised head fastener, such as a buttonhead-type rivet, used to join together structural skins, such as aluminum aircraft skins. The probe has a recessed concave dimple in its bottom surface that closely conforms to the shape of the raised head. The concave dimple holds the probe in good alignment on top of the rivet while the probe is rotated around the rivet's centerline. One or more magnetic coils are rigidly embedded within the probe's cylindrical body, which is made of a non-conducting material. This design overcomes the inspection impediment associated with widely varying conductivity in fastened joints.
Large-Scale First-Principles Molecular Dynamics simulations on the BlueGene/L Platform
Franchetti, Franz
. Keywords Electronic structure. Molecular Dynamics. Ab initio simulations. First-principles simulations of the electronic properties of the system. The electronic structure calculation is the most time-consuming part the past three decades to the development of efficient implementations of the electronic structure
The Application of Computational Models for the Simulation of Large-Scale
Johnson, Chris
of Glasgow, Scotland. http://www.dcs.gla.ac.uk/~johnson Abstract. Over the last five years, we have developed a range of stochastic techniques for simulating the evacuation of public buildings. These have included this work is to support a form of `mitigation engineering'. Evacuation simulations help us to reduce
Simulating the High Energy Gamma-ray sky seen by the GLAST Large Area Telescope
F. Longo; P. Azzi; D. Bastieri; G. Busetto; Y. Lei; R. Rando; O. Tibolla; L. Baldini; M. Kuss; L. Latronico; N. Omodei; M. Razzano; G. Spandre; P. Boinee; A. De Angelis; M. Frailis; M. Brigida; F. Gargano; N. Giglietto; F. Loparco; M. N. Mazziotta; C. Cecchi; P. Lubrano; F. Marcucci; M. Pepe; G. Tosti; A. Lionetto; A. Morselli; C. Pittori
2005-03-24T23:59:59.000Z
This paper presents the simulation of the GLAST high energy gamma-ray telescope. The simulation package, written in C++, is based on the Geant4 toolkit, and it is integrated into a general framework used to process events. A detailed simulation of the electronic signals inside Silicon detectors has been provided and it is used for the particle tracking, which is handled by a dedicated software. A unique repository for the geometrical description of the detector has been realized using the XML language and a C++ library to access this information has been designed and implemented. A new event display based on the HepRep protocol was implemented. The full simulation was used to simulate a full week of GLAST high energy gamma-ray observations. This paper outlines the contribution developed by the Italian GLAST software group.
Eddy-current-induced multipole field calculations.
Sereno, N. S.; Kim, S. H.
2003-10-15T23:59:59.000Z
Time-varying magnetic fields of magnets in booster accelerators induce substantial eddy currents in the vacuum chambers. The eddy currents in turn act to produce various multipole fields that act on the beam. These fields must be taken into account when doing a lattice design. In the APS booster, the relatively long dipole magnets (3 meters) are linearly ramped to accelerate the injected 325 MeV beam to 7 GeV. Substantial dipole and sextupole fields are generated in the elliptical vacuum chamber from the induced eddy currents. In this note, formulas for the induced dipole and sextupole fields are derived for elliptical and rectangular vacuum chambers for a time-varying dipole field. A discussion is given on how to generalize this derivation method to include eddy-current-induced multipole fields from higher multipole magnets (quadrupole, sextupole, etc.). Finally, transient effects are considered.
Statistical and Directable Methods for Large-Scale Rigid Body Simulation
Hsu, Shu-Wei
2013-05-07T23:59:59.000Z
, we develop a mixed rigid body simulator that combines an impulse-based with a statistically-based collision response method. This allows us to maintain high accuracy in important parts of the scene while achieving greater efficiency by simplifying...
Chen, Qiang
2005-08-29T23:59:59.000Z
Following an introduction, the author describes Texas A&M University and its utilities system. After that, the author presents how to construct simulation models for chilled water and heating hot water distribution systems. ...
Author's personal copy Experimental validation of large-scale simulations of dynamic fracture along
Rosakis, Ares J.
in monolithic homo- geneous brittle solids and along weak interfaces between homo- geneous solids has also been for the fitting of parameters. Then, the results of these simulations are validated against those of experiments
Experimental validation of large-scale simulations of dynamic fracture along weak planes
Huerta, Antonio
of the opening-mode crack initiation and the subsequent crack growth phenomenon both in monolithic homo- geneous are often insufficient to completely setup a simulation, which therefore leaves room for the fitting
Modeling and Simulation of Advanced Nano-Scale Very Large Scale Integration Circuits
Zhou, Ying
2010-07-14T23:59:59.000Z
) performance and yield, and (4) new physical synthesis optimization flow is used to shed area and reduce the power consumption. Interconnect parasitic extraction plays an important role in simulation, verification, optimization. A fast and accurate parasitic...
Zhan, Hongbin
). Each of these models was used to fit the breakthrough curve (BTC) at each distance individually not explain the distinct BTC tailing satisfactorily. In contrast to MIM, CTRW bet- ter simulated the long
John A. Sidles; Joseph L. Garbini; Lee E. Harrell; Alfred O. Hero; Jonathan P. Jacky; Joseph R. Malcomb; Anthony G. Norman; Austin M. Williamson
2008-05-13T23:59:59.000Z
This article presents numerical recipes for simulating high-temperature and non-equilibrium quantum spin systems that are continuously measured and controlled. The notion of a spin system is broadly conceived, in order to encompass macroscopic test masses as the limiting case of large-j spins. The simulation technique has three stages: first the deliberate introduction of noise into the simulation, then the conversion of that noise into an equivalent continuous measurement and control process, and finally, projection of the trajectory onto a state-space manifold having reduced dimensionality and possessing a Kahler potential of multi-linear form. The resulting simulation formalism is used to construct a positive P-representation for the thermal density matrix. Single-spin detection by magnetic resonance force microscopy (MRFM) is simulated, and the data statistics are shown to be those of a random telegraph signal with additive white noise. Larger-scale spin-dust models are simulated, having no spatial symmetry and no spatial ordering; the high-fidelity projection of numerically computed quantum trajectories onto low-dimensionality Kahler state-space manifolds is demonstrated. The reconstruction of quantum trajectories from sparse random projections is demonstrated, the onset of Donoho-Stodden breakdown at the Candes-Tao sparsity limit is observed, a deterministic construction for sampling matrices is given, and methods for quantum state optimization by Dantzig selection are given.
Crack detection using pulsed eddy current stimulated thermography
Kostson, E.; Weekes, B.; Almond, D. P. [RCNDE, Department of Mechanical Engineering, University of Bath (United Kingdom); Wilson, J.; Tian, G. Y. [School of Electrical, Electronic and Computer Engineering, Newcastle University (United Kingdom)
2011-06-23T23:59:59.000Z
This contribution presents results from studies investigating factors that influence the detection of surface breaking cracks using pulsed eddy current thermography. The influences of the current strength and crack orientation in both ferromagnetic and non-ferromagnetic metals have been investigated. It has been found that crack detection is far more sensitive to crack orientation in non-ferromagnetic metals than in ferromagnetic metals. The effects of crack size on detectability are presented for a large number of steel, nickel alloy and titanium samples. Results of studies comparing crack images obtained prior and after coating a nickel alloy sample with a thermal barrier coating are presented.
Zhang, Keni; Moridis, G.J.; Wu, Y.-S.; Pruess, K.
2008-07-01T23:59:59.000Z
Simulation of the system behavior of hydrate-bearing geologic media involves solving fully coupled mass- and heat-balance equations. In this study, we develop a domain decomposition approach for large-scale gas hydrate simulations with coarse-granularity parallel computation. This approach partitions a simulation domain into small subdomains. The full model domain, consisting of discrete subdomains, is still simulated simultaneously by using multiple processes/processors. Each processor is dedicated to following tasks of the partitioned subdomain: updating thermophysical properties, assembling mass- and energy-balance equations, solving linear equation systems, and performing various other local computations. The linearized equation systems are solved in parallel with a parallel linear solver, using an efficient interprocess communication scheme. This new domain decomposition approach has been implemented into the TOUGH+HYDRATE code and has demonstrated excellent speedup and good scalability. In this paper, we will demonstrate applications for the new approach in simulating field-scale models for gas production from gas-hydrate deposits.
Forward and Adjoint Simulations of Seismic Wave Propagation on Emerging Large-Scale GPU
Komatitsch, Dimitri
--Computational seismology is an area of wide so- ciological and economic impact, ranging from earthquake risk assessment to subsurface imaging and oil and gas exploration. At the core of these simulations is the modeling of wave different methods such as mesh coloring or atomic updates on the GPU. In order to achieve strong scaling, we
A Parallel P^3M Code for Very Large Scale Cosmological Simulations
Tom MacFarland; Jakob Pichlmeier; Frazer Pearce; Hugh Couchman
1997-08-07T23:59:59.000Z
We have developed a parallel Particle-Particle, Particle-Mesh (P^3M) simulation code for the T3E well suited to studying the time evolution of systems of particles interacting via gravity and gas forces in cosmological contexts. The parallel code is based upon the public-domain serial Adaptive P^3M code of Couchman et al(1). The algorithm resolves gravitational forces into a long range component computed by discretizing the mass distribution and solving Poisson's equation on a grid using an FFT convolution method, and a short range component computed by direct force summation for sufficiently close particle pairs. The code consists primarily of a particle-particle computation parallelized by domain decomposition over blocks of neighbor-cells, a more regular mesh calculation distributed in planes along one dimension, and several transformations between the two distributions. Great care was taken throughout to make optimal use of the available memory, so that the current implementation is capable of simulating systems approaching 10^9 particles using a 1024^3 mesh for the long range force computation. These are thus among the largest N-body simulations ever carried out. We discuss these memory optimizations as well as those motivated by computational performance. Results from production runs have been very encouraging, and even prior to the implimentation of the full adaptive scheme the code has been used effectively for simulations in which the particle distribution becomes highly clustered as well as for other non-uniform systems of astrophysical interest.
Modeling ramp compression experiments using large-scale molecular dynamics simulation.
Mattsson, Thomas Kjell Rene; Desjarlais, Michael Paul; Grest, Gary Stephen; Templeton, Jeremy Alan; Thompson, Aidan Patrick; Jones, Reese E.; Zimmerman, Jonathan A.; Baskes, Michael I. (University of California, San Diego); Winey, J. Michael (Washington State University); Gupta, Yogendra Mohan (Washington State University); Lane, J. Matthew D.; Ditmire, Todd (University of Texas at Austin); Quevedo, Hernan J. (University of Texas at Austin)
2011-10-01T23:59:59.000Z
Molecular dynamics simulation (MD) is an invaluable tool for studying problems sensitive to atomscale physics such as structural transitions, discontinuous interfaces, non-equilibrium dynamics, and elastic-plastic deformation. In order to apply this method to modeling of ramp-compression experiments, several challenges must be overcome: accuracy of interatomic potentials, length- and time-scales, and extraction of continuum quantities. We have completed a 3 year LDRD project with the goal of developing molecular dynamics simulation capabilities for modeling the response of materials to ramp compression. The techniques we have developed fall in to three categories (i) molecular dynamics methods (ii) interatomic potentials (iii) calculation of continuum variables. Highlights include the development of an accurate interatomic potential describing shock-melting of Beryllium, a scaling technique for modeling slow ramp compression experiments using fast ramp MD simulations, and a technique for extracting plastic strain from MD simulations. All of these methods have been implemented in Sandia's LAMMPS MD code, ensuring their widespread availability to dynamic materials research at Sandia and elsewhere.
Simulation Support for Optimizing the Design and Operation of a Large Open-Space Office Building
Lain, M.; Hensen, J.; Zemlicka, J.
2008-01-01T23:59:59.000Z
and simulation was used to predict the performance of various design alternatives with respect to reducing the required cooling capacity, in order to verify the fan-coil capacity sizing and to optimize the ventilation system and strategy of the atriums. Since...
Numerical Simulation of Displacement Ventilation in a Gymnasium in a Large Space Building
Wu, X.; Li, X.
2006-01-01T23:59:59.000Z
. However, there still remains a lot to do in providing a suitable airflow pattern for competitions, with less energy consumption. Recently the displacement ventilation (DV) system has been adopted in northern Europe. It is used in large spaces...
Generation of strong mesoscale eddies by weak ocean gyres by Michael A. Spall1
Generation of strong mesoscale eddies by weak ocean gyres by Michael A. Spall1 ABSTRACT The generation of strong mesoscale variability through instability of the large-scale circulation in the interior with the scaling theory. 1. Introduction It is now well recognized that the kinetic energy of the mesoscale
Rupture mechanism of liquid crystal thin films realized by large-scale molecular simulations
Nguyen, Trung D [ORNL] [ORNL; Carrillo, Jan-Michael Y [ORNL] [ORNL; Brown, W Michael [ORNL] [ORNL; Matheson, Michael A [ORNL] [ORNL
2014-01-01T23:59:59.000Z
The ability of liquid crystal (LC) molecules to respond to changes in their environment makes them an interesting candidate for thin film applications, particularly in bio-sensing, bio-mimicking devices, and optics. Yet the understanding of the (in)stability of this family of thin films has been limited by the inherent challenges encountered by experiment and continuum models. Using unprecedented largescale molecular dynamics (MD) simulations, we address the rupture origin of LC thin films wetting a solid substrate at length scales similar to those in experiment. Our simulations show the key signatures of spinodal instability in isotropic and nematic films on top of thermal nucleation, and importantly, for the first time, evidence of a common rupture mechanism independent of initial thickness and LC orientational ordering. We further demonstrate that the primary driving force for rupture is closely related to the tendency of the LC mesogens to recover their local environment in the bulk state. Our study not only provides new insights into the rupture mechanism of liquid crystal films, but also sets the stage for future investigations of thin film systems using peta-scale molecular dynamics simulations.
Glider Path-Planning for Optimal Sampling of Mesoscale Eddies
Smith, Ryan N.
Glider Path-Planning for Optimal Sampling of Mesoscale Eddies Daniel Hernandez1 , Ryan Smith2 these, mesoscale eddies are of particular interest due to the relevance they have in many oceano
CHARACTERIZATION OF MAGNETRON SPUTTERED COATINGS BY PULSED EDDY CURRENT TECHNIQUES
Danon, Yaron
CHARACTERIZATION OF MAGNETRON SPUTTERED COATINGS BY PULSED EDDY CURRENT TECHNIQUES Chris Mulligan1, Troy, NY 12180 ABSTRACT. A method that uses induced pulsed eddy currents for characterization of thick
Three dimensional simulations of Richtmyer-Meshkov instabilities in shock-tube experiments
Gowardhan, Akshay A [Los Alamos National Laboratory; Grinstein, Fernando F [Los Alamos National Laboratory; Wachtor, Adam J [Los Alamos National Laboratory
2010-01-01T23:59:59.000Z
In the large eddy simulation (LES) approach large-scale energy-containing structures are resolved, smaller (presumably) more isotropic structures are filtered out, and unresolved subgrid effects are modeled. Extensive recent work has demonstrated that predictive simulations of turbulent velocity fields are possible based on subgrid scale modeling implicitly provided by a class of high-resolution finite-volume algorithms. This strategy is called implicit LES. The extension of the approach to the substantially more difficult problem of material mixing IS addressed, and progress in representative shock-driven turbulent mixing studies is reported.
Eddy Currents and Magnetic Calibrations in LDX using a
Eddy Currents and Magnetic Calibrations in LDX using a "Copper Plasma" D.P. Boyle, PPPL M.E. Mauel Calibrate magnetic diagnostics positions and gains Find eddy current decay times Copper Plasma Operation electronically Would be better to measure positions and total gains magnetically #12;Goal: Eddy Currents Magnetic
Eddy-current testing with the Expected Improvement optimization algorithm
Paris-Sud XI, Université de
Eddy-current testing with the Expected Improvement optimization algorithm S´andor Bilicz , Emmanuel presents an inverse problem methodology in the domain of non-destructive testing, and more precisely eddy-current in the light of preliminary numerical examples obtained using synthetic data. Keywords: eddy current testing
Automatic Detection of Defects in Riveted Lapjoints using Eddy Current
Automatic Detection of Defects in Riveted Lapjoints using Eddy Current Fredrik Lingvall Tadeusz originating from rivet holes in a riveted lapjoint using eddy current (EC) inspection is presented consisted of median filtering, rotation and debiasing of the eddy current pattern. The rotation
A JUSTIFICATION OF EDDY CURRENTS MODEL FOR THE MAXWELL EQUATIONS
Buffa, Annalisa
A JUSTIFICATION OF EDDY CURRENTS MODEL FOR THE MAXWELL EQUATIONS H. AMMARI, A. BUFFA, AND J.-C. NÂ1823 Abstract. This paper is concerned with the approximation of the Maxwell equations by the eddy currents model, which appears as a correction of the quasi-static model. The eddy currents model is obtained
MODELING OF EDDY CURRENT LOSS AND TEMPERATURE OF THE MAGNETS
Mi, Chunting "Chris"
MODELING OF EDDY CURRENT LOSS AND TEMPERATURE OF THE MAGNETS IN PERMANENT MAGNET MACHINES@umich.edu Received 24 November 2010 Accepted 16 June 2011 The eddy current loss in the magnets of permanent magnet- mium-iron-boron (NdFeB), and slot/tooth harmonics, there is eddy current loss generated inside
Nondestructive Evaluation of Plates Using Eddy Current Methods
Nondestructive Evaluation of Plates Using Eddy Current Methods David C. Dobson Department in structures using eddy current methods is investigated. The goal of this work is to assess the extent to which a conductivity anomaly from eddy current data is quite unstable, and a method based on leastsquares principle
STATISTICAL ASSESSMENT OF PROBABILITY OF DETECTION FOR AUTOMATED EDDY CURRENT
STATISTICAL ASSESSMENT OF PROBABILITY OF DETECTION FOR AUTOMATED EDDY CURRENT NONDESTRUCTIVE for Nondestructive Evaluation, Iowa State University, Ames, Iowa, USA Abstract: Eddy current inspection is widely response collected using our motion controlled eddy current inspection system, are used in the analysis
WIRELESS EDDY CURRENT PROBE FOR ENGINE HEALTH , B. Graubard1
Dickerson, Julie A.
WIRELESS EDDY CURRENT PROBE FOR ENGINE HEALTH MONITORING M. Reid1 , B. Graubard1 , R. J. Weber1 , J. The first prototype wireless eddy current (EC) probe for on-wing inspection was demonstrated in a F100 PW of safety significant propulsion system malfunctions. Data from 2 MHz Eddy Current probes was transmitted
ADAPTIVE FINITE ELEMENT FREQUENCY DOMAIN METHOD FOR EDDY CURRENT PROBLEMS
Zheng, Weiying
ADAPTIVE FINITE ELEMENT FREQUENCY DOMAIN METHOD FOR EDDY CURRENT PROBLEMS WEIYING ZHENG-harmonic eddy current problems in the case of three-dimensional isotropic and linear materials. We adopt. Time-harmonic Maxwell's equations, eddy current, adaptive finite element method, multiply connected
HHFW (High Harmonic Fast Wave) Eddy Current Analysis for Antenna
Princeton Plasma Physics Laboratory
1 NSTX HHFW (High Harmonic Fast Wave) Eddy Current Analysis for Antenna NSTX-CALC-24-03-01 June 1 performed.) The model was first built for NSTX to verify the eddy current effect on antenna during plasma force of the induced eddy current in the components. The force data was transferred to the structural
Nondestructive Evaluation of Plates Using Eddy Current Methods
Santosa, Fadil
Nondestructive Evaluation of Plates Using Eddy Current Methods David C. Dobson \\Lambda Department in structures using eddy current methods is investigated. The goal of this work is to assess the extent to which anomaly from eddy current data is quite unstable, and a method based on leastsquares principle would fail
Quantitative Imaging of Corrosion in Plates by Eddy Current Methods
Santosa, Fadil
Quantitative Imaging of Corrosion in Plates by Eddy Current Methods Bruno Luong \\Lambda and Fadil the problem of determining material loss due to corÂ rosion in a plate. Eddy current data are collected on one the relationship between eddy current loop impedance change with the loss profile. In this context, we show
Surfzone eddies in strong alongshore currents: Forced or Instabilities?
Frandsen, Jannette B.
Surfzone eddies in strong alongshore currents: Forced or Instabilities? Falk Feddersen Associate by surfzone 2D turbulent eddies, which have length-scales > the water depth. Our group's results regarding surfzone eddy-induced mixing learned from dye, drifter, theory, and modeling will be reviewed - however
Numerical Analysis of Nonlinear Multiharmonic Eddy Current Problems
Schoeberl, Joachim
Numerical Analysis of Nonlinear Multiharmonic Eddy Current Problems F. Bachinger U. Langer J. Sch¨oberl April 2004 Abstract This work provides a complete analysis of eddy current problems, rang- ing from at providing a complete analysis of general nonlinear eddy current problems and their numerical treatment
Surf zone eddies coupled with rip current morphology
Kirby, James T.
Surf zone eddies coupled with rip current morphology Jamie H. MacMahan Oceanography Department. Thornton, and T. P. Stanton (2004), Surf zone eddies coupled with rip current morphology, J. Geophys. Res) surf zone eddies (SZEs) were observed on a beach composed of shore-connected shoals with quasi
Corner singularities of Maxwell interface and eddy current problems
Costabel, Martin
Corner singularities of Maxwell interface and eddy current problems Martin Costabel, Monique Dauge permittivity/conductivity tends to zero (the eddy current limit). Corner singularities of the Maxwell transmission problem and also of the eddy current model have been described elsewhere [6, 7]. Here we
Eddy formation and propagation in the eastern tropical Pacific
Jhingran, Vikas Gopal
1997-01-01T23:59:59.000Z
eddies are caused by winds blowing offshore from the coast of Central America. Plots of eddy tracks from TOPEX data show that some of these eddies last for over 6 months and travel more than 250 of longitude toward the west. Others go more towards...
MESOSCALE EDDIES Peter B. Rhines, University of Washington,
MESOSCALE EDDIES Peter B. Rhines, University of Washington, School of Oceanography, Box 357940, Seattle, WA 98195 7940, USA Copyright ^ 2001 Academic Press doi:10.1006/rwos.2001.0143 Mesoscale eddies that strongly feel viscosity, to `mesoscale eddies' that strongly feel the Earth's rota- tion, to great `gyres
Casimir interaction from magnetically coupled eddy currents
Francesco Intravaia; Carsten Henkel
2009-09-06T23:59:59.000Z
We study the quantum and thermal fluctuations of eddy (Foucault) currents in thick metallic plates. A Casimir interaction between two plates arises from the coupling via quasi-static magnetic fields. As a function of distance, the relevant eddy current modes cross over from a quantum to a thermal regime. These modes alone reproduce previously discussed thermal anomalies of the electromagnetic Casimir interaction between good conductors. In particular, they provide a physical picture for the Casimir entropy whose nonzero value at zero temperature arises from a correlated, glassy state.
Casimir Interaction from Magnetically Coupled Eddy Currents
Intravaia, Francesco; Henkel, Carsten [Institut fuer Physik und Astronomie, Universitaet Potsdam, 14476 Potsdam (Germany)
2009-09-25T23:59:59.000Z
We study the quantum and thermal fluctuations of eddy (Foucault) currents in thick metallic plates. A Casimir interaction between two plates arises from the coupling via quasistatic magnetic fields. As a function of distance, the relevant eddy current modes cross over from a quantum to a thermal regime. These modes alone reproduce previously discussed thermal anomalies of the electromagnetic Casimir interaction between good conductors. In particular, they provide a physical picture for the Casimir entropy whose nonzero value at zero temperature arises from a correlated, glassy state.
Eddy Correlation Flux Measurement System (ECOR) Handbook
Cook, DR
2011-01-31T23:59:59.000Z
The eddy correlation (ECOR) flux measurement system provides in situ, half-hour measurements of the surface turbulent fluxes of momentum, sensible heat, latent heat, and carbon dioxide (CO2) (and methane at one Southern Great Plains extended facility (SGP EF) and the North Slope of Alaska Central Facility (NSA CF). The fluxes are obtained with the eddy covariance technique, which involves correlation of the vertical wind component with the horizontal wind component, the air temperature, the water vapor density, and the CO2 concentration.
A model for red blood cells in simulations of large-scale blood flows
Simone Melchionna
2011-07-25T23:59:59.000Z
Red blood cells (RBCs) are an essential component of blood. A method to include the particulate nature of blood is introduced here with the goal of studying circulation in large-scale realistic vessels. The method uses a combination of the Lattice Boltzmann method (LBM) to account for the plasma motion, and a modified Molecular Dynamics scheme for the cellular motion. Numerical results illustrate the quality of the model in reproducing known rheological properties of blood as much as revealing the effect of RBC structuring on the wall shear stress, with consequences on the development of cardiovascular diseases.
Isolating the role of mesoscale eddies in mixing of a passive tracer in an eddy resolving model
Miami, University of
Isolating the role of mesoscale eddies in mixing of a passive tracer in an eddy resolving model February 2008; published 16 May 2008. [1] This study examines the role of mesoscale eddies in distribution was replaced by a down-gradient diffusive parameterization. Our results demonstrate that advection by mesoscale
Demand Shifting With Thermal Mass in Large Commercial Buildings:Field Tests, Simulation and Audits
Xu, Peng; Haves, Philip; Piette, Mary Ann; Zagreus, Leah
2005-09-01T23:59:59.000Z
The principle of pre-cooling and demand limiting is to pre-cool buildings at night or in the morning during off-peak hours, storing cooling in the building thermal mass and thereby reducing cooling loads and reducing or shedding related electrical demand during the peak periods. Cost savings are achieved by reducing on-peak energy and demand charges. The potential for utilizing building thermal mass for load shifting and peak demand reduction has been demonstrated in a number of simulation, laboratory, and field studies (Braun 1990, Ruud et al. 1990, Conniff 1991, Andresen and Brandemuehl 1992, Mahajan et al. 1993, Morris et al. 1994, Keeney and Braun 1997, Becker and Paciuk 2002, Xu et al. 2003). This technology appears to have significant potential for demand reduction if applied within an overall demand response program. The primary goal associated with this research is to develop information and tools necessary to assess the viability of and, where appropriate, implement demand response programs involving building thermal mass in buildings throughout California. The project involves evaluating the technology readiness, overall demand reduction potential, and customer acceptance for different classes of buildings. This information can be used along with estimates of the impact of the strategies on energy use to design appropriate incentives for customers.
Diagnosis of Ocean Mesoscale Eddy Tracer Fluxes
Fox-Kemper, Baylor
Diagnosis of Ocean Mesoscale Eddy Tracer Fluxes Baylor Fox-Kemper U. Colorado-Boulder, with Scott - 10,000 km, yrs->centuries) => resolved · Mesoscale variability (10 - 100 km, mo -> yrs) => resolved) => parameterized Boundary Layer Models Mesoscale resolving models Climate models Submesoscale variability Coupling
Accelerated Profile HMM Searches Sean R. Eddy *
Eddy, Sean
Accelerated Profile HMM Searches Sean R. Eddy * Abstract Profile hidden Markov models (profile HMMs search. However, practical use of profile HMM methods has been hindered by the computational expense of existing software implementations. Here I describe an acceleration heuristic for profile HMMs
RACORO continental boundary layer cloud investigations. 2. Large-eddy
Office of Scientific and Technical Information (OSTI)
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 to3,1,50022,3,,0,,6,1,SeparationConnect JournalPentoxide. (Journalpolyethyleneterephthalate(Conference) |R-axion detection at
Fedorczak, N. [Center for Momentum Transport and Flow Organization, University of California at San Diego, San Diego, California 92093 (United States); CEA, IRFM, F-13108 Saint-Paul-Lez-Durance (France); Manz, P. [Center for Momentum Transport and Flow Organization, University of California at San Diego, San Diego, California 92093 (United States); Max-Planck-Institut feur Plasmaphysik, Association Euratom-IPP, 85748Garching (Germany); Thakur, S. C.; Xu, M.; Tynan, G. R. [Center for Momentum Transport and Flow Organization, University of California at San Diego, San Diego, California 92093 (United States); Xu, G. S.; Liu, S. C. [Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031 (China)
2012-12-15T23:59:59.000Z
Time delay estimation (TDE) techniques are frequently used to estimate the flow velocity from fluctuating measurements. Tilted structures carried by the flow lead to misinterpretation of the time delays in terms of velocity direction and amplitude. It affects TDE measurements from probes, and is also intrinsically important for beam emission spectroscopy and gas puff imaging measurements. Local eddy shapes estimated from 2D fluctuating field are necessary to gain a more accurate flow estimate from TDE, as illustrated by Langmuir probe array measurements. A least square regression approach is proposed to estimate both flow field and shaping parameters. The technique is applied to a test case built from numerical simulation of interchange fluctuations. The local eddy shape does not only provide corrections for the velocity field but also quantitative information about the statistical interaction mechanisms between local eddies and E Multiplication-Sign B flow shear. The technique is then tested on gaz puff imaging data collected at the edge of EAST tokamak plasmas. It is shown that poloidal asymmetries of the fluctuation fields-velocity and eddy shape-are consistent at least qualitatively with a ballooning type of turbulence immersed in a radially sheared equilibrium flow.
Aldrin, John C. [Computational Tools, Gurnee, IL 60031 (United States); Sabbagh, Harold A.; Murphy, R. Kim; Sabbagh, Elias H. [Victor Technologies LLC, Bloomington, IN 47401 (United States)
2011-06-23T23:59:59.000Z
Recent advances are presented to model discontinuities in random anisotropies that arise in certain materials, such as titanium alloys. A numerical model is developed to provide a full anisotropic representation of each crystalline in a gridded region of the material. Several simulated and experimental demonstrations are presented highlighting the effect of grain noise on eddy current measurements. Agreement between VIC-3D(c) model calculations and experimental data in titanium alloy specimens with known flaws is demonstrated.
Bogliolo, Alessandro
for design evaluation. A large number of power estimation techniques has been proposed [1]Â[4] based, the large number of simulations needed to reach a significant estimate of average power dissipation further and valida- tion. When optimizing for power, several transformations are applied to a circuit to reduce its
Contoured Surface Eddy Current Inspection System
Batzinger, Thomas James (Burnt Hills, NY); Fulton, James Paul (Clifton Park, NY); Rose, Curtis Wayne (Mechanicville, NY); Perocchi, Lee Cranford (Schenectady, NY)
2003-04-08T23:59:59.000Z
Eddy current inspection of a contoured surface of a workpiece is performed by forming a backing piece of flexible, resiliently yieldable material with a contoured exterior surface conforming in shape to the workpiece contoured surface. The backing piece is preferably cast in place so as to conform to the workpiece contoured surface. A flexible eddy current array probe is attached to the contoured exterior surface of the backing piece such that the probe faces the contoured surface of the workpiece to be inspected when the backing piece is disposed adjacent to the workpiece. The backing piece is then expanded volumetrically by inserting at least one shim into a slot in the backing piece to provide sufficient contact pressure between the probe and the workpiece contoured surface to enable the inspection of the workpiece contoured surface to be performed.
Mitchell, John Anthony; Epp, David S.; Wittwer, Jonathan W.
2005-10-01T23:59:59.000Z
Damping vibrations is important in the design of some types of inertial sensing devices. One method for adding damping to a device is to use magnetic forces generated by a static magnetic field interacting with eddy currents. In this report, we develop a 2-dimensional finite element model for the analysis of quasistatic eddy currents in a thin sheet of conducting material. The model was used for design and sensitivity analyses of a novel mechanical oscillator that consists of a shuttle mass (thin sheet of conducting material) and a set of folded spring elements. The oscillator is damped through the interaction of a static magnetic field and eddy currents in the shuttle mass. Using a prototype device and Laser Dopler Velocimetry (LDV), measurements were compared to the model in a validation study using simulation based uncertainty analyses. Measurements were found to follow the trends predicted by the model.
INNOVATIVE EDDY CURRENT PROBE FOR MICRO DEFECTS
Santos, Telmo G.; Vilaca, Pedro; Quintino, Luisa [IDMEC, Av. Rovisco Pais, 1049-001 Lisbon (Portugal); Santos, Jorge dos [GKSS, Max-Planck-Street 1, D-21502 Geesthacht (Germany); Rosado, Luis [IST, UTL, Av. Rovisco Pais, 1049-001 Lisbon (Portugal)
2010-02-22T23:59:59.000Z
This paper reports the development of an innovative eddy current (EC) probe, and its application to micro-defects on the root of the Friction Stir Welding (FSW). The new EC probe presents innovative concept issues, allowing 3D induced current in the material, and a lift-off independence. Validation experiments were performed on aluminium alloys processed by FSW. The results clearly show that the new EC probe is able to detect and sizing surface defects about 60 microns depth.
Eddy current inspection tool. [Patent application
Petrini, R.R.; Van Lue, D.F.
1980-10-29T23:59:59.000Z
A miniaturized inspection tool, for testing and inspection of metal objects in locations with difficult accessibility, which comprises eddy current sensing equipment with a probe coil, and associated coaxial coil cable, oil energizing means, and circuit means responsive to impedance changes in the coil as effected by induced eddy currents in a test object to produce a data output signal proportional to such changes. The coil and cable are slideably received in the utility channel of the flexible insertion tube of a fiberoptic scope. The scope is provided with light transmitting and receiving fiberoptics for viewing through the flexible tube, and articulation means for articulating the distal end of the tube and permitting close control of coil placement relative to a test object. The eddy current sensing equipment includes a tone generator for generating audible signals responsive to the data output signal. In one selected mode of operation, the tone generator responsive to the output signal above a selected level generates a constant single frequency tone for signalling detection of a discontinuity and, in a second selected mode, generates a tone whose frequency is proportional to the difference between the output signal and a predetermined selected threshold level.
Beckstein, Oliver
). These classes of simulation will place increasing demands on different aspects of high performance computing
Hamann, Bernd
JOURNAL OF GEOPHYSICAL RESEARCH: OCEANS, VOL. 118, 17591 , doi:10.1002/jgrc.20155, 2013 A three-dimensional eddy census of a high-resolution global ocean simulation Mark R. Petersen,1 Sean J. Williams,1,2 Mathew from a global ocean simulation with one-tenth degree resolution and a duration of 7 years. The census
Adaptive finite element method for eddy current problems
Adaptive finite element method for eddy current problems. In this chapter we shall discuss Maxwell's equations at very low frequencies. We also refer to [bo98 ...
A TRANSIENT EDDY CURRENT PROBLEM ON A MOVING DOMAIN. MATHEMATICAL ANALYSIS
RodrÃguez, Rodolfo
A TRANSIENT EDDY CURRENT PROBLEM ON A MOVING DOMAIN. MATHEMATICAL ANALYSIS ALFREDO BERM is to introduce and analyze a weak formulation of the transient eddy current problem governing electromagnetic. Electromagnetic forming, transient eddy current problem, axisymmetric problem, degenerate parabolic problem
RodrÃguez, Rodolfo
Numerical solution of transient eddy current problems with input current intensities as boundary to solve transient eddy current problems with input current intensities as data, formulated in terms: Eddy current problems, time-dependent electromagnetic problems, input current intensities, finite
MATHEMATICAL AND NUMERICAL ANALYSIS OF A TRANSIENT EDDY CURRENT PROBLEM ARISING FROM
RodrÃguez, Rodolfo
MATHEMATICAL AND NUMERICAL ANALYSIS OF A TRANSIENT EDDY CURRENT PROBLEM ARISING FROM transient axisymmetric eddy current problem governing such phenomenon. The resulting problem is degenerate. Electromagnetic forming, finite elements, eddy current, transient electromagnetics, degenerate parabolic problems
Griesel, Alexa
in the southern recirculation gyre region, near topographic obstacles and down- stream in the KE jet, where, correlate well with the magnitudes of eddy velocity. The KE jet suppresses cross- stream mixing only in some better than those in bins defined by a regular geographic grid. Cross-stream diffusivities are elevated
Minnesota, University of
the Agulhas Current, which flows along the southeastern coast of Africa and around the tip of South Africa dynamics. In addition to dominating the ocean's kinetic energy, eddies play a significant role. The ocean's kinetic energy is dominated by mesoscale variability: scales of tens to hundreds of kilometers
Eddy current measurement of tube element spacing
Latham, Wayne Meredith (Forest, VA); Hancock, Jimmy Wade (Lynchburg, VA); Grut, Jayne Marie (Madison Heights, VA)
1998-01-01T23:59:59.000Z
A method of electromagnetically measuring the distance between adjacent tube elements in a heat exchanger. A cylindrical, high magnetic permeability ferrite slug is placed in the tube adjacent the spacing to be measured. A bobbin or annular coil type probe operated in the absolute mode is inserted into a second tube adjacent the spacing to be measured. From prior calibrations on the response of the eddy current coil, the signals from the coil, when sensing the presence of the ferrite slug, are used to determine the spacing between the tubes.
Accelerated profile HMM searches Sean R. Eddy1,
Eddy, Sean
1 Accelerated profile HMM searches Sean R. Eddy1, 1 HHMI Janelia Farm Research Campus, Ashburn, VA, USA. E-mail: eddys@janelia.hhmi.org Abstract Profile hidden Markov models (profile HMMs search. However, practical use of profile HMM methods has been hindered by the computational expense
Characterization of Caribbean Meso-Scale Eddies Jose M. Lopez
Gilbes, Fernando
Characterization of Caribbean Meso-Scale Eddies Jose M. Lopez Department of Marine Sciences, P will be subjected to 3-D spectrofluorometry and scanning spectrophotometry for CDOM characterization (J. Corredor, J. Morell). Current structure across fronts and eddies will be characterized by means of ship-lowered ADCP
MODELING OF EDDY CURRENT LOSS AND TEMPERATURE OF THE MAGNETS
Mi, Chunting "Chris"
MODELING OF EDDY CURRENT LOSS AND TEMPERATURE OF THE MAGNETS IN PERMANENT MAGNET MACHINES the performance of the machine. This paper presents the modeling and analysis of eddy current loss in surface- mounted-magnets PM synchronous motors (SPMSM) and interior-magnets PM synchronous motors (IPMSM), operated
Wang, Weiguo; Davis, Kenneth J.
2008-09-03T23:59:59.000Z
We compare the contributions of unit source fluxes over a clear-cutting area in a forest and over the contiguous forested area to the eddy-covariance (EC) flux of CO2 measured at a tower standing in the center of the clearcut under daytime convective conditions. The large-eddy simulation (LES) technique is used to simulate the dispersion and transport of two conservative and passive tracers that are released from the clearcut and from the forested area, respectively. The time series of the LES-generated vertical velocity and the mixing ratios of both tracers on all the levels at the tower location are recorded every model time step during the last hour of each LES run; this somewhat mimics real EC flux measurements at the tower. The contribution of the unit surface flux over the clearcut relative to that over the forested area decreases exponentially with increasing measurement height, decreasing convective boundary layer depth, increasing atmospheric stability, and decreasing size of the clearcut. LES-derived results are fitted to an empirical relation and applied to flux measurements at the 447-m tall tower in Wisconsin, USA. The contribution of the unit flux over the clearcut on the EC flux measured at the 30-m level of the tower is larger than 50% of that over the forested area under most unstable conditions, while smaller than 2.5% at the 396-m level. Existing analytical footprint models are inappropriate to address the clearcut influence due to clearcut-induced heterogeneity of the turbulent flow in the tower area.
Kemner, Ken
Eddy-Current-Induced Multipole Field Calculations September 29, 2003 1 Eddy-Current-Induced Multipole Field Calculations Nicholas S. Sereno, Suk H. Kim 1.0 Abstract Time-varying magnetic fields-current-induced multipole fields from higher multipole magnets (quadrupole, sextupole, etc.). Finally, transient effects
Eddy Current for Sizing Cracks in Canisters for Dry Storage of Used Nuclear Fuel
Meyer, Ryan M.; Jones, Anthony M.; Pardini, Allan F.
2014-01-01T23:59:59.000Z
The storage of used nuclear fuel (UNF) in dry canister storage systems (DCSSs) at Independent Spent Fuel Storage Installations (ISFSI) sites is a temporary measure to accommodate UNF inventory until it can be reprocessed or transferred to a repository for permanent disposal. Policy uncertainty surrounding the long-term management of UNF indicates that DCSSs will need to store UNF for much longer periods than originally envisioned. Meanwhile, the structural and leak-tight integrity of DCSSs must not be compromised. The eddy current technique is presented as a potential tool for inspecting the outer surfaces of DCSS canisters for degradation, particularly atmospheric stress corrosion cracking (SCC). Results are presented that demonstrate that eddy current can detect flaws that cannot be detected reliably using standard visual techniques. In addition, simulations are performed to explore the best parameters of a pancake coil probe for sizing of SCC flaws in DCSS canisters and to identify features in frequency sweep curves that may potentially be useful for facilitating accurate depth sizing of atmospheric SCC flaws from eddy current measurements.
SOURCE SEPARATION TECHNIQUES APPLIED TO THE DETECTION OF SUBSURFACE DEFECTS IN THE EDDY CURRENT NDT
Paris-Sud XI, Université de
SOURCE SEPARATION TECHNIQUES APPLIED TO THE DETECTION OF SUBSURFACE DEFECTS IN THE EDDY CURRENT NDT component analysis, to process the data from the eddy current inspection of riveted lap joints. An eddy methods are proposed for processing such eddy current data by means of both the considered source
Eddy currents in a gradient coil, modeled as circular loops of strips
Eindhoven, Technische Universiteit
Eddy currents in a gradient coil, modeled as circular loops of strips J.M.B. Kroot, S.J.L. van to induction, eddy currents occur, resulting in a so-called edge-effect. Higher frequencies cause stronger edge by a gradient coil induces eddy currents in the conducting structures. The eddy currents cause perturbations
Feng, Ming
Physical and chemical signatures of a developing anticyclonic eddy in the Leeuwin Current, eastern 2006 to sample a developing anticyclonic eddy of the Leeuwin Current off Western Australia. The eddy to that of the Leeuwin Current, indicating the water mass in the eddy is mainly derived from the Leeuwin Current
Classical eddy current losses in Soft Magnetic Composites , O. de la Barrire2a
Paris-Sud XI, Université de
1 Classical eddy current losses in Soft Magnetic Composites C. Appino1 , O. de la Barrière2a , F. It is known that eddy currents can flow in these granular materials at3 two different scales, that of the single particle (microscopic eddy currents) and that of the specimen4 cross-section (macroscopic eddy
Modeled biogeochemical responses to mesoscale eddies in the South China Sea
Maine, University of
Modeled biogeochemical responses to mesoscale eddies in the South China Sea Peng Xiu1 and Fei Chai1] Mesoscale eddies are observed each year in the South China Sea (SCS); however, their contributions physicalbiogeochemical model to evaluate the eddy impact. We first track the modeled mesoscale eddies in the SCS
Wind ringing of the ocean in presence of mesoscale eddies P. Klein and G. Lapeyre
Lapeyre, Guillaume
Wind ringing of the ocean in presence of mesoscale eddies P. Klein and G. Lapeyre Laboratoire de scales related to oceanic mesoscale eddies. Results show that a turbulent eddy field does not affect Oceanography: Physical: Eddies and mesoscale processes; 4572 Oceanography: Physical: Upper ocean processes
Mesoscale eddies, satellite altimetry, and new production in the Sargasso Sea
Siegel, David A.
Mesoscale eddies, satellite altimetry, and new production in the Sargasso Sea David A. Siegel1 to characterize the mesoscale eddy field in the Sargasso Sea near Bermuda and to address the role of physical pumping. Eddy pumping is the process by which mesoscale eddies induce isopycnal displacements that lift
MULTI-DOMAIN INDUSTRIAL BENCHMARKS FOR EDDY CURRENT MODELING: THE COFREND WORKING GROUP
Paris-Sud XI, Université de
Conference on Non-Destructive Testing (ECNDT 2010), Moscou : France (2010)" #12;Concerning eddy currents
On the role of mesoscale eddies in the ventilation of Antarctic intermediate water
Fischlin, Andreas
On the role of mesoscale eddies in the ventilation of Antarctic intermediate water Zouhair Lachkar Mesoscale eddies CFC-11 Ventilation Southern Ocean a b s t r a c t The spatial distribution of Antarctic and ventilation are substantially affected by mesoscale eddies. To diagnose the role of eddies, we made global CFC
Qiu, Bo
Seasonal Mesoscale and Submesoscale Eddy Variability along the North Pacific Subtropical abundant in mesoscale eddies, but also exhibits prominent submesoscale eddy features. Output from a 1 the seasonal STCC variability in the mesoscale versus submesoscale ranges. Resolving the eddy scales of .150 km
Qin, Hong; Xiao, Jianyuan; Zhang, Ruili; He, Yang; Wang, Yulei; Burby, Joshua W; Ellison, Leland; Zhou, Yao
2015-01-01T23:59:59.000Z
Particle-in-Cell (PIC) simulation is the most important numerical tool in plasma physics and accelerator physics. However, its long-term accuracy has not been established. To overcome this difficulty, we developed a canonical symplectic PIC method for the Vlasov-Maxwell system by discretizing the Marsden-Weinstein bracket. A fast local algorithm to solve the symplectic implicit time advance is discovered without root researching or global matrix inversion, enabling applications of the proposed method to very large-scale plasma simulations with many, e.g., $10^{9}$, degrees of freedom.
Eddy heat fluxes at Drake Passage due to mesoscale motions
Rojas Recabal, Ricardo Luis
1982-01-01T23:59:59.000Z
EDDY HEAT FLUKES AT DRAKE PASSAGE DUE TO MESOSCALE MOTIONS A Thesis by RICARDO LUIS ROJAS RECABAL Submitted to the Graduate College of Texas A&M University in partial fulfillment of the requirement for the degree of MASTER OF SCIENCE May... 1982 Major Subject: Oceanography EDDY HEAT FLUXES AT DRAKE PASSAGE DUE TO MESOSCALE NOTIONS A Thesis by RICARDO LUIS ROJAS RECABAL Approved as to style and content by: was )W-~ Member em er May 1982 ABSTRACT Eddy Heat Fluxes at Drake Passage...
Eddy heat fluxes at Drake Passage due to mesoscale motions
Rojas Recabal, Ricardo Luis
1982-01-01T23:59:59.000Z
EDDY HEAT FLUKES AT DRAKE PASSAGE DUE TO MESOSCALE MOTIONS A Thesis by RICARDO LUIS ROJAS RECABAL Submitted to the Graduate College of Texas A&M University in partial fulfillment of the requirement for the degree of MASTER OF SCIENCE May... 1982 Major Subject: Oceanography EDDY HEAT FLUXES AT DRAKE PASSAGE DUE TO MESOSCALE NOTIONS A Thesis by RICARDO LUIS ROJAS RECABAL Approved as to style and content by: was )W-~ Member em er May 1982 ABSTRACT Eddy Heat Fluxes at Drake Passage...
Oakley, Jeremy
-Based Ambulance Service model on Geographical Information System. 3. To develop a Discrete Event Simulation model services. The incorporation of geographical information systems (GIS) can provide precise data Services Improvement Anastasia Anagnostou and Simon Taylor School of Information Systems, Computing
Guglielmetti, R.; Pless, S.; Torcellini, P.
2010-08-01T23:59:59.000Z
This paper illustrates the challenges of integrating rigorous daylight and electric lighting simulation data with whole-building energy models, and defends the need for such integration to achieve aggressive energy savings. Through a case study example, we examine the ways daylighting -- and daylighting simulation -- drove the design of a large net-zero energy project. We give a detailed review of the daylighting and electric lighting design process for the National Renewable Energy Laboratory's Research Support Facility (RSF), a 220,000 ft2 net-zero energy project the author worked on as a daylighting consultant. A review of the issues involved in simulating and validating the daylighting performance of the RSF will be detailed, including daylighting simulation, electric lighting control response, and integration of Radiance simulation data into the building energy model. Daylighting was a key strategy in reaching the contractual energy use goals for the RSF project; the building's program, layout, orientation and interior/furniture design were all influenced by the daylighting design, and simulation was critical in ensuring these many design components worked together in an integrated fashion, and would perform as required to meet a very aggressive energy performance goal, as expressed in a target energy use intensity.
Eddy-current-damped microelectromechanical switch
Christenson, Todd R. (Albuquerque, NM); Polosky, Marc A. (Tijeras, NM)
2007-10-30T23:59:59.000Z
A microelectromechanical (MEM) device is disclosed that includes a shuttle suspended for movement above a substrate. A plurality of permanent magnets in the shuttle of the MEM device interact with a metal plate which forms the substrate or a metal portion thereof to provide an eddy-current damping of the shuttle, thereby making the shuttle responsive to changes in acceleration or velocity of the MEM device. Alternately, the permanent magnets can be located in the substrate, and the metal portion can form the shuttle. An electrical switch closure in the MEM device can occur in response to a predetermined acceleration-time event. The MEM device, which can be fabricated either by micromachining or LIGA, can be used for sensing an acceleration or deceleration event (e.g. in automotive applications such as airbag deployment or seat belt retraction).
Eddy-current-damped microelectromechanical switch
Christenson, Todd R. (Albuquerque, NM); Polosky, Marc A. (Tijeras, NM)
2009-12-15T23:59:59.000Z
A microelectromechanical (MEM) device is disclosed that includes a shuttle suspended for movement above a substrate. A plurality of permanent magnets in the shuttle of the MEM device interact with a metal plate which forms the substrate or a metal portion thereof to provide an eddy-current damping of the shuttle, thereby making the shuttle responsive to changes in acceleration or velocity of the MEM device. Alternately, the permanent magnets can be located in the substrate, and the metal portion can form the shuttle. An electrical switch closure in the MEM device can occur in response to a predetermined acceleration-time event. The MEM device, which can be fabricated either by micromachining or LIGA, can be used for sensing an acceleration or deceleration event (e.g. in automotive applications such as airbag deployment or seat belt retraction).
Eddy-mean flow interactions in western boundary current jets
Waterman, Stephanie N
2009-01-01T23:59:59.000Z
This thesis examines the nature of eddy-mean flow interactions in western boundary current jets and recirculation gyre dynamics from both theoretical and observational perspectives. It includes theoretical studies of ...
Eddy sensors for small diameter stainless steel tubes.
Skinner, Jack L.; Morales, Alfredo Martin; Grant, J. Brian; Korellis, Henry James; LaFord, Marianne Elizabeth; Van Blarigan, Benjamin; Andersen, Lisa E.
2011-08-01T23:59:59.000Z
The goal of this project was to develop non-destructive, minimally disruptive eddy sensors to inspect small diameter stainless steel metal tubes. Modifications to Sandia's Emphasis/EIGER code allowed for the modeling of eddy current bobbin sensors near or around 1/8-inch outer diameter stainless steel tubing. Modeling results indicated that an eddy sensor based on a single axial coil could effectively detect changes in the inner diameter of a stainless steel tubing. Based on the modeling results, sensor coils capable of detecting small changes in the inner diameter of a stainless steel tube were designed, built and tested. The observed sensor response agreed with the results of the modeling and with eddy sensor theory. A separate limited distribution SAND report is being issued demonstrating the application of this sensor.
Estimating Suppression of Eddy Mixing by Mean Flows
Klocker, Andreas
Particle- and tracer-based estimates of lateral diffusivities are used to estimate the suppression of eddy mixing across strong currents. Particles and tracers are advected using a velocity field derived from sea surface ...
Mesoscale Eddies in the Gulf of Alaska: Observations and Implications
Rovegno, Peter
2012-01-01T23:59:59.000Z
Chao, Y. 2012. Modeling the mesoscale eddy field in the GulfShriver, J. F. 2001. Mesoscale variability in the boundaryof the Gulf of Alaska mesoscale circulation. Progress in
Analysis of azimuthal mode dynamics of mesoscale eddies
McCalpin, John David
1984-01-01T23:59:59.000Z
ANALYSIS OF AZIMUTHAL MODE DYNAMICS OF MESOSCALE EDDIES A Thesis by UOHN DAVID MCCALPIN Submitted to the Graduate College of Texas ASM University in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE August 1984... Major Subject: Oceanography ANALYSIS OF AZIMUTHAL MODE DYNAMICS OF MESOSCALE EDDIES A Thesis by JOHN DAVID MCCALPIN Approved as to style and content by: rew . as ano (Chairman of Committee) o ert . ei (Member) uy . rancesc &ni (Member) Robert...
Analysis of azimuthal mode dynamics of mesoscale eddies
McCalpin, John David
1984-01-01T23:59:59.000Z
ANALYSIS OF AZIMUTHAL MODE DYNAMICS OF MESOSCALE EDDIES A Thesis by UOHN DAVID MCCALPIN Submitted to the Graduate College of Texas ASM University in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE August 1984... Major Subject: Oceanography ANALYSIS OF AZIMUTHAL MODE DYNAMICS OF MESOSCALE EDDIES A Thesis by JOHN DAVID MCCALPIN Approved as to style and content by: rew . as ano (Chairman of Committee) o ert . ei (Member) uy . rancesc &ni (Member) Robert...
Pradipta, Rezy
2012-01-01T23:59:59.000Z
In this thesis, we investigate the potential role played by large-scale anomalous heat sources (e.g. prolonged heat wave events) in generating acoustic-gravity waves (AGWs) that might trigger widespread plasma turbulence ...
Wang, Liang; Stinson, Gregory S; Macciò, Andrea V; Penzo, Camilla; Kang, Xi; Keller, Ben W; Wadsley, James
2015-01-01T23:59:59.000Z
We introduce project NIHAO (Numerical Investigation of a Hundred Astrophysical Objects), a set of 100 cosmological zoom-in hydrodynamical simulations performed using the GASOLINE code, with an improved implementation of the SPH algorithm. The haloes in our study range from dwarf to Milky Way masses, and represent an unbiased sampling of merger histories, concentrations and spin parameters. The particle masses and force softenings are chosen to resolve the mass profile to below 1% of the virial radius at all masses, ensuring that galaxy half-light radii are well resolved. Using the same treatment of star formation and stellar feedback for every object, the simulated galaxies reproduce the observed inefficiency of galaxy formation across cosmic time as expressed through the stellar mass vs halo mass relation, and the star formation rate vs stellar mass relation. We thus conclude that stellar feedback is the chief piece of physics required to limit the efficiency of star formation in galaxies less massive than t...
Nagy, Peter B.
Journal of Nondestructive Evaluation, Vol. 23, No. 3, September 2004 ( C 2004) Eddy Current in eddy current conductivity at increasing inspection frequencies, which can be exploited components, lend themselves easily for eddy current residual stress assessment lies in their favorable
Elmroth, Erik
A Parallel Implementation of the TOUGH2 Software Package for Large Scale Multiphase Fluid and Heat groundwater flow related problems such as nuclear waste isolation, environmental remediation, and geothermal with ¢¡¤£¦¥§ ¨¡© blocks in a Yucca Mountain nuclear waste site study. Keywords. Ground water flow, grid partitioning
Elmroth, Erik
A Parallel Implementation of the TOUGH2 Software Package for Large Scale Multiphase Fluid and Heat groundwater flow related problems such as nuclear waste isolation, environmental remediation, and geothermal 6 blocks in a Yucca Mountain nuclear waste site study. Keywords. Ground water flow, grid
Ku?el, Petr
, University of Belgrade, Pregrevica 118, 11080 Belgrade, Serbia Division of Chemical Physics, Lund University frequencies is thermally activated but with a much smaller activation energy compared to the dc case, the dc transport is thermally activated with activation energies which can be as large as 350 me
Maury Cuna, H; Zimmermann, F
2012-01-01T23:59:59.000Z
The heat load generated by an electron cloud in the cold arcs of the Large Hadron Collider (LHC) is a concern for operation near and beyond nominal beam current. We report the results of simulation studies, with updated secondary- emission models, which examine the severity of the electron heat load over a range of possible operation parameters, both for the nominal LHC and for various luminosity-upgrade scenarios, such as the so-called ‘‘full crab crossing’’ and ‘‘early separation’’ schemes, the ‘‘large Piwinski angle’’ scheme, and a variant of the latter providing ‘‘compatibility’’ with the (upgraded) LHCb experiment. The variable parameters considered are the maximum secondary-emission yield, the number of particles per bunch, and the spacing between bunches. In addition, the dependence of the heat load on the longitudinal bunch profile is investigated.
METAMODELS AS INPUT OF AN OPTIMIZATION ALGORITHM FOR SOLVING AN INVERSE EDDY CURRENT TESTING PROBLEM
Boyer, Edmond
METAMODELS AS INPUT OF AN OPTIMIZATION ALGORITHM FOR SOLVING AN INVERSE EDDY CURRENT TESTING-Curie, 91192 Gif-sur-Yvette, France Abstract A new mean of solution of eddy current testing (ECT) inverse
Bates, Michael
Observations and theory suggest that lateral mixing by mesoscale ocean eddies only reaches its maximum potential at steering levels, surfaces at which the propagation speed of eddies approaches that of the mean flow. Away ...
Energy pathways and structures of oceanic eddies from the ECCO2 State Estimate and Simplified Models
Chen, Ru, Ph. D. Massachusetts Institute of Technology
2013-01-01T23:59:59.000Z
Studying oceanic eddies is important for understanding and predicting ocean circulation and climate variability. The central focus of this dissertation is the energy exchange between eddies and mean ow and banded structures ...
Mixed Layer Lateral Eddy Fluxes Mediated by Air-Sea Interaction
Shuckburgh, Emily
The modulation of air–sea heat fluxes by geostrophic eddies due to the stirring of temperature at the sea surface is discussed and quantified. It is argued that the damping of eddy temperature variance by such air–sea ...
CgWind: A high-order accurate simulation tool for wind turbines and wind farms
Chand, K K; Henshaw, W D; Lundquist, K A; Singer, M A
2010-02-22T23:59:59.000Z
CgWind is a high-fidelity large eddy simulation (LES) tool designed to meet the modeling needs of wind turbine and wind park engineers. This tool combines several advanced computational technologies in order to model accurately the complex and dynamic nature of wind energy applications. The composite grid approach provides high-quality structured grids for the efficient implementation of high-order accurate discretizations of the incompressible Navier-Stokes equations. Composite grids also provide a natural mechanism for modeling bodies in relative motion and complex geometry. Advanced algorithms such as matrix-free multigrid, compact discretizations and approximate factorization will allow CgWind to perform highly resolved calculations efficiently on a wide class of computing resources. Also in development are nonlinear LES subgrid-scale models required to simulate the many interacting scales present in large wind turbine applications. This paper outlines our approach, the current status of CgWind and future development plans.
Eddy Current Testing for Detecting Small Defects in Thin Films
Obeid, Simon; Tranjan, Farid M. [Electrical and Computer Engineering Department, UNCC (United States); Dogaru, Teodor [Albany Instruments, 426-O Barton Creek, Charlotte, NC 28262 (United States)
2007-03-21T23:59:59.000Z
Presented here is a technique of using Eddy Current based Giant Magneto-Resistance sensor (GMR) to detect surface and sub-layered minute defects in thin films. For surface crack detection, a measurement was performed on a copper metallization of 5-10 microns thick. It was done by scanning the GMR sensor on the surface of the wafer that had two scratches of 0.2 mm, and 2.5 mm in length respectively. In another experiment, metal coatings were deposited over the layers containing five defects with known lengths such that the defects were invisible from the surface. The limit of detection (resolution), in terms of defect size, of the GMR high-resolution Eddy Current probe was studied using this sample. Applications of Eddy Current testing include detecting defects in thin film metallic layers, and quality control of metallization layers on silicon wafers for integrated circuits manufacturing.
On the simulation of shock-driven material mixing in high-Re flows (u)
Grinstein, Fernando F [Los Alamos National Laboratory
2009-01-01T23:59:59.000Z
Implicit large eddy simulation proposes to effectively rely on the use of subgrid modeling and filtering provided implicitly by physics capturing numerics. Extensive work has demonstrated that predictive simulations of turbulent velocity fields are possible using a class of high resolution, non-oscillatory finite-volume (NFV) numerical algorithms. Truncation terms associated with NFV methods implicitly provide subgrid models capable of emulating the physical dynamics of the unresolved turbulent velocity fluctuations by themselves. The extension of the approach to the substantially more difficult problem of under-resolved material mixing by an under-resolved velocity field has not yet been investigated numerically, nor are there any theories as to when the methodology may be expected to be successful. Progress in addressing these issues in studies of shock-driven scalar mixing driven by Ritchmyer-Meshkov instabilities will be reported in the context of ongoing simulations of shock-tube laboratory experiments.
Jet Interaction and the Influence of a Minimum Phase Speed Bound on the Propagation of Eddies
Vallis, Geoff
Jet Interaction and the Influence of a Minimum Phase Speed Bound on the Propagation of Eddies and analogs of the midlatitude eddy-driven jet and the subtropical jet is investigated in a barotropic b-plane model. In the model the subtropical jet is generated by a relaxation process and the eddy-driven jet
A Diagnostic Suite of Models for the Evaluation of Oceanic Mesoscale Eddy Parameterizations
Fox-Kemper, Baylor
A Diagnostic Suite of Models for the Evaluation of Oceanic Mesoscale Eddy Parameterizations by S. D of Oceanic Mesoscale Eddy Parameterizations written by S. D. Bachman has been approved for the Department and Oceanic Sciences) A Diagnostic Suite of Models for the Evaluation of Oceanic Mesoscale Eddy
Wadley, Haydn
Modeling multifrequency eddy current sensor interactions during vertical Bridgman growth methods have been used to analyze the responses of two ``absolute'' and ``differential'' eddy current conductivity ratio increases. Of the materials studied, GaAs is found best suited for eddy current sensing
An H-Formulation for the Three-Dimensional Eddy Current Problem in Laminated Structures
Zheng, Weiying
An H- Formulation for the Three-Dimensional Eddy Current Problem in Laminated Structures Peijun Li-dimensional eddy currents in grain-oriented (GO) silicon steel laminations since the coating film is only several to the smallest scale can be up to 106. In this paper, we study an H- formulation for the nonlinear eddy current
EDDY CURRENT TESTING OF FERROMAGNETIC MATERIALS: MODELLING OF MULTIPLE FLAWS IN A
Paris-Sud XI, Université de
EDDY CURRENT TESTING OF FERROMAGNETIC MATERIALS: MODELLING OF MULTIPLE FLAWS IN A PLANAR STRATIFIED Université Paris Sud 11), 3, rue Joliot-Curie, 91192 Gif-sur- Yvette, France ! "#$%&'(%! Eddy current testing. Lambert, H. Voillaume and N. Dominguez, "A 3D model for eddy current inspection in aeronautics
AN ADAPTIVE FINITE ELEMENT METHOD FOR THE EDDY CURRENT MODEL WITH CIRCUIT/FIELD COUPLINGS
AN ADAPTIVE FINITE ELEMENT METHOD FOR THE EDDY CURRENT MODEL WITH CIRCUIT/FIELD COUPLINGS JUNQING for solving the eddy current model with voltage excitations for complicated three dimensional structures of the proposed method. Key words. Eddy current, circuit/field coupling, adaptivity, a posteriori error analysis
IEEE TRANS. MAGN., SUBMITTED 1 3D Eddy-Current Imaging of Metal Tubes by
Paris-Sud XI, Université de
IEEE TRANS. MAGN., SUBMITTED 1 3D Eddy-Current Imaging of Metal Tubes by Gradient-Based, Controlled, and Oliver Dorn Abstract--Eddy-current non-destructive testing is widely used to detect defects within-developed binary-specialized method. Index Terms--eddy-current non-destructive testing, impedance variations, level
A generalized likelihood ratio technique for automated analysis of bobbin coil eddy current dataq
Polikar, Robi
A generalized likelihood ratio technique for automated analysis of bobbin coil eddy current dataq M signals that are commonly found in bobbin coil eddy current data. The performance of the proposed for automated processing and classi®cation of eddy current data. q 2002 Elsevier Science Ltd. All rights
EUROPEAN CONFERENCE FOR AEROSPACE SCIENCES Study on the eddy current damping of the spin dynamics of
Paris-Sud XI, Université de
4TH EUROPEAN CONFERENCE FOR AEROSPACE SCIENCES Study on the eddy current damping of the spin consideration in this article, are impacted by torques generated by eddy currents as the conducting non, the permanent magnetic field from the magnetosphere generates eddy current in the spinning, conducting body
2258 IEEE TRANSACTIONS ON MAGNETICS, VOL. 33, NO. 3, MAY 1997 Pulsed Eddy-Current Response
Bowler, John R.
2258 IEEE TRANSACTIONS ON MAGNETICS, VOL. 33, NO. 3, MAY 1997 Pulsed Eddy-Current Response to a Conducting Half-Space John Bowler, Member, IEEE, and Marcus Johnson Abstract-- Eddy-current nondestructive agreement between theory and experiment. Index Terms--Eddy current, half-space, pulsed, transient. I
Low-frequency perturbation theory in eddy-current non-destructive evaluation
Bowler, John R.
Low-frequency perturbation theory in eddy-current non-destructive evaluation N. Harfield,a) Y series solutions for the impedance change in an eddy-current test probe due to closed cracks in a non structures in, for example, the nuclear power and aero- space industries. Eddy-current inspection methods
NUMERICAL TREATMENT OF REALISTIC BOUNDARY CONDITIONS FOR THE EDDY CURRENT PROBLEM IN AN
RodrÃguez, Rodolfo
NUMERICAL TREATMENT OF REALISTIC BOUNDARY CONDITIONS FOR THE EDDY CURRENT PROBLEM IN AN ELECTRODE methods to solve the eddy current problem in a conducting bounded domain. In particular, we consider-frequency harmonic Maxwell equations, eddy current problems, finite element computational electromagnetism, Lagrange
MATHEMATICAL AND NUMERICAL ANALYSIS OF A TRANSIENT EDDY CURRENT AXISYMMETRIC PROBLEM
RodrÃguez, Rodolfo
MATHEMATICAL AND NUMERICAL ANALYSIS OF A TRANSIENT EDDY CURRENT AXISYMMETRIC PROBLEM INVOLVING to solve a tran- sient eddy current axisymmetric problem. We consider the case of a coil supplied with a source current generating a magnetic field which induces eddy currents in a nearby workpiece
Fitzpatrick, Richard
Observation of tearing mode deceleration and locking due to eddy currents induced in a conducting eddy currents induced by the rotating mode in the conducting shell surrounding the plasma. According to the amplitude of the mode.47 According to this theory, eddy currents induced in the conducting shell
Singularities of eddy current problems Martin Costabel, Monique Dauge, Serge Nicaise
Singularities of eddy current problems Martin Costabel, Monique Dauge, Serge Nicaise May 13, 2003 Abstract We consider the time-harmonic eddy current problem in its electric formulation where the conductor60. 1 Maxwell equations and the eddy current limit Let us consider the model case of an homogeneous
Eddy currents in a gradient coil, modelled as circular loops of strips
Eindhoven, Technische Universiteit
Eddy currents in a gradient coil, modelled as circular loops of strips J.M.B. Kroot, S.J.L. van. Due to induction eddy currents occur which lead to the so-called edge-effect. The edge- effect depends the gradient coils themselves. Eddy currents occur, causing perturbations on the expected gradient field
Anisotropic grain noise in eddy current inspection of noncubic polycrystalline metals
Nagy, Peter B.
Anisotropic grain noise in eddy current inspection of noncubic polycrystalline metals Mark Blodgett of microstructural noise. In eddy current inspection of noncubic crystallographic classes of polycrystalline metals the electrical grain noise is clearly detrimental in eddy current nondestructive testing for small flaws, it can
PROOF COPY 018405PHP Observation of tearing mode deceleration and locking due to eddy currents
Fitzpatrick, Richard
to eddy currents induced in a conducting shell B. E. Chapman Department of Physics, University 6, 3878 1999 in which a braking torque originates from eddy currents induced by the rotating mode, eddy currents induced in the conducting shell surrounding the plasma exert a braking torque
AN E-BASED MIXED FORMULATION FOR A TIME-DEPENDENT EDDY CURRENT PROBLEM
RodrÃguez, Rodolfo
AN E-BASED MIXED FORMULATION FOR A TIME-DEPENDENT EDDY CURRENT PROBLEM RAMIRO ACEVEDO, SALIM-quasistatic submodel usually called eddy current problem; see for instance [9, Chapter 8]. From the mathematical point this harmonic behavior, leading to the so-called time-harmonic eddy current problem. However, even in the case
Eddy current coil interaction with a right-angled conductive wedge
Bowler, John R.
Eddy current coil interaction with a right-angled conductive wedge BY T. P. THEODOULIDIS 1 AND J. R: eddy current; conductive wedge; coil impedance 1. Introduction The quasi-static electromagnetic field whose axis is normal to one of the wedge faces. The problem has applications in eddy current non
Calculation of eddy currents in moving structures by a sliding mesh-nite element method
Buffa, Annalisa
Calculation of eddy currents in moving structures by a sliding mesh- nite element method A. Bu of eddy currents in non-stationary structures. Both 2D and 3D models are considered. The approximation. An implicit Euler scheme is used to discretize in time. Key words { eddy currents, nite element approxima
Time domain half-space dyadic Green's functions for eddy-current calculations
Bowler, John R.
Time domain half-space dyadic Green's functions for eddy-current calculations J. R. Bowlera) Centre American Institute of Physics. S0021-8979 99 08422-4 I. TIME DOMAIN INTERACTION The calculation of eddy-current-domain eddy-current scattering problems for cases in which a scat- terer is embedded in an otherwise
Analysis of eddy currents in a gradient coil J.M.B. Kroot
Eindhoven, Technische Universiteit
Analysis of eddy currents in a gradient coil J.M.B. Kroot Eindhoven University of Technology P in the tangential direction as well, due to eddy currents induced by other coils. In order to take the dependence, and the frequency is low enough to allow for a quasistatic approximation. Due to induction eddy currents occur
Analysis of eddy currents in a gradient coil J.M.B. Kroot
Eindhoven, Technische Universiteit
Analysis of eddy currents in a gradient coil J.M.B. Kroot Eindhoven University of Technology P in the tangential direction as well, due to eddy currents induced by other coils. In order to take the dependence, and the frequency is low enough to allow for a quasi-static approximation. Due to induction eddy currents occur
Analytical Model of Magnet Eddy-Current Volume Losses in Multi-phase PM Machines
Paris-Sud XI, Université de
Analytical Model of Magnet Eddy-Current Volume Losses in Multi-phase PM Machines with Concentrated, 94000 Créteil France Abstract--this paper studies magnet eddy-current losses in permanent magnet (PM calculations. Keywords--Traction, Concentrated Winding, Eddy- Current, Volume Magnet Losses, Multiphase Machine
Angular approach combined to mechanical model for tool breakage detection by eddy current sensors
Paris-Sud XI, Université de
1 Angular approach combined to mechanical model for tool breakage detection by eddy current sensors solution is proposed for the estimate of cutting force using eddy current sensors implemented close eccentricity obtained during the machining from the eddy current sensors signals. Efficiency and reliability
Numerical analysis of electric field formulations of the eddy current model
RodrÃguez, Rodolfo
Numerical analysis of electric field formulations of the eddy current model Alfredo BermÂ´udez1 methods for the numeri- cal solution of the eddy current problem in a bounded conducting domain crossed): 78M10, 65N30 Key words Low-frequency harmonic Maxwell equations, eddy currents, finite elements
An eddy current problem related to electromagnetic Alfredo Bermudez, Rafael Mu~noz, Pilar Salgado
RodrÃguez, Rodolfo
An eddy current problem related to electromagnetic forming Alfredo BermÂ´udez, Rafael Mu~noz, Pilar is to analyze a numerical method to solve a transient axisymmetric eddy current problem arising from currents in the workpiece. The magnetic field, together with the eddy currents, originate the Lorentz
Nagy, Peter B.
2007-01-01T23:59:59.000Z
NDT&E International 40 (2007) 405418 High-frequency eddy current conductivity spectroscopy Available online 11 February 2007 Abstract Recent research results indicated that eddy current conductivity-conductivity engine alloys the eddy current penetration depth could not be forced below 0.2 mm without expanding
AN ADAPTIVE FINITE ELEMENT METHOD FOR THE H -FORMULATION OF TIME-DEPENDENT EDDY CURRENT
AN ADAPTIVE FINITE ELEMENT METHOD FOR THE H - FORMULATION OF TIME-DEPENDENT EDDY CURRENT PROBLEMS, eddy current problem, adaptive finite element method, mul- tiply connected conductor, Team Workshop Problem 7 AMS subject classifications. 65M60, 65M50, 78A25 1. Introduction. Eddy currents appear in almost
Eddy-current interaction with an ideal crack. II. The inverse problem John FL Bowler
Bowler, John R.
Eddy-current interaction with an ideal crack. II. The inverse problem John FL Bowler The University 1994) Eddy-current inversion is the process whereby the geometry of a flaw in a metal is derived from eddy-current probe impedance measurements. The approach is based on an optimization scheme that seeks
STABILIZATION OF KINK INSTABILITIES BY EDDY CURRENTS IN A SEGMENTED WALL AND
Mauel, Michael E.
STABILIZATION OF KINK INSTABILITIES BY EDDY CURRENTS IN A SEGMENTED WALL AND COMPARISON WITH IDEAL and measured equi- librium wall eddy currents. The stability analysis of these equilibria predicts patterns of instability induced eddy currents for a model wall that is continuous and perfectly conducting
Near-Surface Eddy Heat and Momentum Fluxes in the Antarctic Circumpolar Current in Drake Passage
Sprintall, Janet
Near-Surface Eddy Heat and Momentum Fluxes in the Antarctic Circumpolar Current in Drake Passage Antarctic Circumpolar Current (ACC) momentum balance. The observations span 7 yr and are compared to eddy Current (ACC) pathway is marked by exceptionally high mesoscale eddy activity (e.g., Stammer 1998; Hughes
Numerical solution of eddy current problems in bounded domains using realistic boundary
RodrÃguez, Rodolfo
Numerical solution of eddy current problems in bounded domains using realistic boundary conditions-called eddy currents. The problem is formulated in terms of the magnetic field. This formulation in a metallurgical arc furnace. Key words: low-frequency harmonic Maxwell equations, eddy current problems, finite
558: Calculation of Eddy Currents in the ETE Spherical Torus G.O. Ludwig
558: Calculation of Eddy Currents in the ETE Spherical Torus G.O. Ludwig Instituto Nacional de model based on the Green's function method. The distribution of eddy currents is calculated using a thin well with values of the eddy currents measured in ETE. INTRODUCTION This paper presents a magnetostatic
Nagy, Peter B.
Numerical method for calculating the apparent eddy current conductivity loss on randomly rough Because of their frequency-dependent penetration depth, eddy current measurements are capable of mapping of eddy current conductivity, thereby decreasing the accuracy of the measurements, especially in thermally
Theory of thin-skin eddy-current interaction with surface cracks N. Harfielda)
Bowler, John R.
Theory of thin-skin eddy-current interaction with surface cracks N. Harfielda) and J. R. Bowler; accepted for publication 14 July 1997 Eddy-current non-destructive evaluation is commonly performed of a typical crack. A thin-skin analysis of eddy currents is presented in which the electromagnetic fields
Mathematical and numerical analysis of a transient non-linear axisymmetric eddy current model
RodrÃguez, Rodolfo
Mathematical and numerical analysis of a transient non-linear axisymmetric eddy current model the theoretically predicted behavior of the method, are reported. Keywords transient eddy current Â· axisymmetric is the accurate computation of power losses in the ferromagnetic components of the core due to hysteresis and eddy-current
Theory of eddy current inversion Stephen:J. Nortona) and John FL Bowler
Bowler, John R.
Theory of eddy current inversion Stephen:J. Nortona) and John FL Bowler University of Surrey) The inverse eddy current problem can be described as the task of reconstructing an unknown distribution of electrical conductivity from eddy-current probe impedance measurements recorded as a function of probe
Eddy-current interaction with an ideal crack. I. The forward problem J. R. Bowler
Bowler, John R.
Eddy-current interaction with an ideal crack. I. The forward problem J. R. Bowler The University February 1994) The impedance of an eddy-current probe changes when the current it induces in an electrical to introduce idealizations about the nature of the flaw. Eddy-current interaction is considered with an ideal
Paris-Sud XI, Université de
for eddy currents Non Destructive Testing and Evaluation FrkddricTHOLLON-Nod BURAIS CEGELY- URA CNRS 829 for cracks detection under installed fasteners in aircraftstructure. I. INTRODUCTION Eddy currents are widely to the eddy current control method : -very smallvariations of sensor response. - many geometrical
DIRECT-DRIVE AND EDDY-CURRENT SEPTUM MAGNETS June 29, 2001
Kemner, Ken
DIRECT-DRIVE AND EDDY-CURRENT SEPTUM MAGNETS S. H. Kim June 29, 2001 Abstract -- Two types of thin septum magnets, direct drive and eddy current, were compared mainly in 2-D magnetic aspects. For the eddy-current type, the leakage fields calculated using OPERA-2d were compared with the calculations
Eddy Current Tomography Using a Binary Markov Mila Nikolova and Ali MohammadDjafari
Nikolova, Mila
Eddy Current Tomography Using a Binary Markov Model Mila Nikolova and Ali Mohammad and notches. The medium is illuminated with a monochromatic electric field; the anomalies induce eddy currents in various fields such as nuclear power plants and aerospace engineering. 1 #12; The objective of eddy
NUMERICAL SOLUTION OF A TRANSIENT NON-LINEAR AXISYMMETRIC EDDY CURRENT MODEL WITH NON-LOCAL
RodrÃguez, Rodolfo
NUMERICAL SOLUTION OF A TRANSIENT NON-LINEAR AXISYMMETRIC EDDY CURRENT MODEL WITH NON@ing-mat.udec.cl This paper deals with an axisymmetric transient eddy current problem in conductive nonlinear magnetic media of the proposed scheme. Keywords: transient eddy current problem; electromagnetic losses; nonlinear magnetic
A simple numerical model of the apparent loss of eddy current conductivity due to surface roughness
Nagy, Peter B.
A simple numerical model of the apparent loss of eddy current conductivity due to surface roughness of eddy current conductivity has been suggested as a possible means to allow the nondestructive evaluation, the path of the eddy current must follow a more tortuous route in the material, which produces a reduction
Improvement of the magnetic core for eddy current losses decreasing in cylindrical linear actuators.
Boyer, Edmond
Improvement of the magnetic core for eddy current losses decreasing in cylindrical linear actuators the power) increases, the iron losses become high [1]. One classical method for reducing the eddy current the eddy current losses in a longitudinal flux multi-rod actuator and to compute improvement. 2 The linear
Efficient Solvers for Nonlinear Time-Periodic Eddy Current F. Bachinger
Schoeberl, Joachim
Efficient Solvers for Nonlinear Time-Periodic Eddy Current Problems F. Bachinger U. Langer J. Sch-periodic eddy current problems, ranging from the description of the nonlinearity to an efficient solution setup, the magnetic field and the thereby generated eddy currents hardly penetrate into conducting
Kurapov, Alexander
Global Observations of Nonlinear Mesoscale Eddies Dudley B. Chelton, Michael G. Schlax and Roger M mesoscale variability in the global ocean. The prevalence of eddy-like structures with scales of O(100 km mesoscale features based on their SSH signatures yields 35,891 eddies with lifetimes 16 weeks. These long
Influence of mesoscale eddies on ichthyoplankton assemblages in the Gulf of Alaska
Influence of mesoscale eddies on ichthyoplankton assemblages in the Gulf of Alaska ELIZABETH ATWOOD 98115, USA ABSTRACT Mesoscale eddies (100200 km in diameter) propa- gating along the shelf in these eddies was examined using data from a cruise in 2005 that sampled three eastern Gulf of Alaska mesoscale
Behaviour of the winter North Atlantic eddy-driven jet stream in the CMIP3 integrations
Barnes, Elizabeth A.
Behaviour of the winter North Atlantic eddy-driven jet stream in the CMIP3 integrations Abdel-Verlag Berlin Heidelberg 2012 Abstract A systematic analysis of the winter North Atlantic eddy-driven jet stream is associated with variations in the westerly eddy-driven jet stream. Extratropical weather and climate
Vessel eddy current measurement for the National Spherical Torus Experiment
Gates, D.A.; Menard, J.E.; Marsala, R.J. [Princeton Plasma Physics Laboratory, P.O. Box 451, Princeton, New Jersey 08543 (United States)
2004-12-01T23:59:59.000Z
A simple analog circuit that measures the National Spherical Torus Experiment (NSTX) axisymmetric eddy current distribution has been designed and constructed. It is based on simple circuit model of the NSTX vacuum vessel that was calibrated using a special axisymmetric eddy current code which was written so that accuracy was maintained in the vicinity of the current filaments [J. Menard, J. Fusion Tech. (to be published)]. The measurement and the model have been benchmarked against data from numerous vacuum shots and they are in excellent agreement. This is an important measurement that helps give more accurate equilibrium reconstructions.
Optimisation of an idealised ocean model, stochastic parameterisation of sub-grid eddies
Fenwick C. Cooper; Laure Zanna
2014-10-21T23:59:59.000Z
An optimisation scheme is developed to accurately represent the sub-grid scale forcing of a high dimensional chaotic ocean system. Using a simple parameterisation scheme, the velocity components of a 30km resolution shallow water ocean model are optimised to have the same climatological mean and variance as that of a less viscous 7.5km resolution model. The 5 day lag-covariance is also optimised, leading to a more accurate estimate of the high resolution response to forcing using the low resolution model. The system considered is an idealised barotropic double gyre that is chaotic at both resolutions. Using the optimisation scheme, we find and apply the constant in time, but spatially varying, forcing term that is equal to the time integrated forcing of the sub-mesoscale eddies. A linear stochastic term, independent of the large-scale flow, with no spatial correlation but a spatially varying amplitude and time scale is used to represent the transient eddies. The climatological mean, variance and 5 day lag-covariance of the velocity from a single high resolution integration is used to provide an optimisation target. No other high resolution statistics are required. Additional programming effort, for example to build a tangent linear or adjoint model, is not required either. The focus of this paper is on the optimisation scheme and the accuracy of the optimised flow. The method can be applied in future investigations into the physical processes that govern barotropic turbulence and it can perhaps be applied to help understand and correct biases in the mean and variance of a more realistic coarse or eddy-permitting ocean model. The method is complementary to current parameterisations and can be applied at the same time without modification.
Sreepathi, Sarat [ORNL] [ORNL; Sripathi, Vamsi [Intel Corporation] [Intel Corporation; Mills, Richard T [ORNL] [ORNL; Hammond, Glenn [Pacific Northwest National Laboratory (PNNL)] [Pacific Northwest National Laboratory (PNNL); Mahinthakumar, Kumar [North Carolina State University] [North Carolina State University
2013-01-01T23:59:59.000Z
Inefficient parallel I/O is known to be a major bottleneck among scientific applications employed on supercomputers as the number of processor cores grows into the thousands. Our prior experience indicated that parallel I/O libraries such as HDF5 that rely on MPI-IO do not scale well beyond 10K processor cores, especially on parallel file systems (like Lustre) with single point of resource contention. Our previous optimization efforts for a massively parallel multi-phase and multi-component subsurface simulator (PFLOTRAN) led to a two-phase I/O approach at the application level where a set of designated processes participate in the I/O process by splitting the I/O operation into a communication phase and a disk I/O phase. The designated I/O processes are created by splitting the MPI global communicator into multiple sub-communicators. The root process in each sub-communicator is responsible for performing the I/O operations for the entire group and then distributing the data to rest of the group. This approach resulted in over 25X speedup in HDF I/O read performance and 3X speedup in write performance for PFLOTRAN at over 100K processor cores on the ORNL Jaguar supercomputer. This research describes the design and development of a general purpose parallel I/O library, SCORPIO (SCalable block-ORiented Parallel I/O) that incorporates our optimized two-phase I/O approach. The library provides a simplified higher level abstraction to the user, sitting atop existing parallel I/O libraries (such as HDF5) and implements optimized I/O access patterns that can scale on larger number of processors. Performance results with standard benchmark problems and PFLOTRAN indicate that our library is able to maintain the same speedups as before with the added flexibility of being applicable to a wider range of I/O intensive applications.
IFP Energies nouvelles International Conference Rencontres Scientifiques d'IFP Energies nouvelles
Boyer, Edmond
LES4ICE 2012 - Large Eddy Simulation for Internal Combustion Engine Flows LES4ICE 2012 - La simulation
DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)
Weijer, Wilbert; Maltrud, Mathew E.; Homoky, William B.; Polzin, Kurt L.; Maas, Leo R. M.
2015-03-27T23:59:59.000Z
In this study, we address the question whether eddy-driven transports in the Argentine Basin can be held responsible for enhanced sediment accumulation over the Zapiola Rise, hence accounting for the existence and growth of this sediment drift. To address this question, we perform a 6 year simulation with a strongly eddying ocean model. We release two passive tracers, with settling velocities that are consistent with silt and clay size particles. Our experiments show contrasting behavior between the silt fraction and the lighter clay. Due to its larger settling velocity, the silt fraction reaches a quasisteady state within a few years,more »with abyssal sedimentation rates that match net input. In contrast, clay settles only slowly, and its distribution is heavily stratified, being transported mainly along isopycnals. Yet, both size classes display a significant and persistent concentration minimum over the Zapiola Rise. We show that the Zapiola Anticyclone, a strong eddy-driven vortex that circulates around the Zapiola Rise, is a barrier to sediment transport, and hence prevents significant accumulation of sediments on the Rise. We conclude that sediment transport by the turbulent circulation in the Argentine Basin alone cannot account for the preferred sediment accumulation over the Rise. We speculate that resuspension is a critical process in the formation and maintenance of the Zapiola Rise.« less
Ching, Wai-Yim [Univ. of Missouri, Kansas City, MO (United States)
2014-12-31T23:59:59.000Z
Advanced materials with applications in extreme conditions such as high temperature, high pressure, and corrosive environments play a critical role in the development of new technologies to significantly improve the performance of different types of power plants. Materials that are currently employed in fossil energy conversion systems are typically the Ni-based alloys and stainless steels that have already reached their ultimate performance limits. Incremental improvements are unlikely to meet the more stringent requirements aimed at increased efficiency and reduce risks while addressing environmental concerns and keeping costs low. Computational studies can lead the way in the search for novel materials or for significant improvements in existing materials that can meet such requirements. Detailed computational studies with sufficient predictive power can provide an atomistic level understanding of the key characteristics that lead to desirable properties. This project focuses on the comprehensive study of a new class of materials called MAX phases, or Mn+1AXn (M = a transition metal, A = Al or other group III, IV, and V elements, X = C or N). The MAX phases are layered transition metal carbides or nitrides with a rare combination of metallic and ceramic properties. Due to their unique structural arrangements and special types of bonding, these thermodynamically stable alloys possess some of the most outstanding properties. We used a genomic approach in screening a large number of potential MAX phases and established a database for 665 viable MAX compounds on the structure, mechanical and electronic properties and investigated the correlations between them. This database if then used as a tool for materials informatics for further exploration of this class of intermetallic compounds.
DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)
Vogelmann, Andrew M.; Fridlind, Ann M.; Toto, Tami; Endo, Satoshi; Lin, Wuyin; Wang, Jian; Feng, Sha; Zhang, Yunyan; Turner, David D.; Liu, Yangang; et al
2015-05-01T23:59:59.000Z
Observation-based modeling case studies of continental boundary layer clouds have been developed to study cloudy boundary layers, aerosol influences upon them, and their representation in cloud- and global-scale models. Three 60-hour case study periods span the temporal evolution of cumulus, stratiform, and drizzling boundary layer cloud systems, representing mixed and transitional states rather than idealized or canonical cases. Based on in-situ measurements from the RACORO field campaign and remote-sensing observations, the cases are designed with a modular configuration to simplify use in large-eddy simulations (LES) and single-column models. Aircraft measurements of aerosol number size distribution are fit to lognormal functionsmore »for concise representation in models. Values of the aerosol hygroscopicity parameter, ?, are derived from observations to be ~0.10, which are lower than the 0.3 typical over continents and suggestive of a large aerosol organic fraction. Ensemble large-scale forcing datasets are derived from the ARM variational analysis, ECMWF forecasts, and a multi-scale data assimilation system. The forcings are assessed through comparison of measured bulk atmospheric and cloud properties to those computed in 'trial' large-eddy simulations, where more efficient run times are enabled through modest reductions in grid resolution and domain size compared to the full-sized LES grid. Simulations capture many of the general features observed, but the state-of-the-art forcings were limited at representing details of cloud onset, and tight gradients and high-resolution transients of importance. Methods for improving the initial conditions and forcings are discussed. The cases developed are available to the general modeling community for studying continental boundary clouds.« less
Bottom Drag, eddy diffusivity, wind work and the power integrals
Young, William R.
Bottom Drag, eddy diffusivity, wind work and the power integrals Bill Young, Andrew Thompson field i.e., the meridional heat flux is pro Moreover, the mechanical energy balance in a statistical Moreover, the mechanical energy balance in a statistically st Appendix A) is U-2 x = | - 2 |2 + hyp
Hayward, Vincent
Initial results using Eddy Current Brakes as Fast Turn-on, Programmable Physical Dampers for Haptic Machines McGill University, Montr´eal, Qu´ebec, Canada ABSTRACT We demonstrate the use of eddy current propose an alternate method to create damping in a haptic interface that uses eddy current brakes. 2 EDDY
Rauhut, Holger
686 IEEE TRANSACTIONS ON MAGNETICS, VOL. 44, NO. 6, JUNE 2008 Estimating the Eddy-Current Modeling Zurich, CH-8092 ZÃ¼rich, Switzerland The eddy-current model is an approximation of the full Maxwell delivers a mathematical basis for assessing the scope of the eddy-current model. Index Terms--Eddy current
Paris-Sud XI, Université de
1358 IEEE TRANSACTIONS ON MAGNETICS, VOL. 40, NO. 2, MARCH 2004 Eddy-Current Effects in Circuit Abstract--This paper deals with the modeling of eddy currents generated by arc motion during opening phases in determining eddy currents in splitter plates, the second one is devoted to the calculation of eddy currents
McHenry, Michael E.
The role of eddy currents and nanoparticle size on AC magnetic fieldinduced reflow in solder://jap.aip.org/about/rights_and_permissions #12;The role of eddy currents and nanoparticle size on AC magnetic fieldinduced reflow in solder be derived from eddy current losses in Cu planes in the substrate board. Eddy current heating in Cu sheets
Rossby wave radiation by an eddy on the polar beta-plane
Zhang, Yang
2015-01-01T23:59:59.000Z
Results from the laboratory experiments on the evolution of vortices (eddies) generated in a rotating tank with topographic beta-effect are presented. The surface elevation and velocity fields are measured by the Altimetric Imaging Velocimetry. The experiments are supplemented by shallow water numerical simulations as well as a linear theory which describes the Rossby wave radiation by travelling vortices. The cyclonic vortices observed in the experiments travel to the northwest and continuously radiate Rossby waves. Measurements show that initially axisymmetric vortices develop a dipolar component which enables them to perform translational motion. A pattern of alternating zonal jets to the west of the vortex is created by Rossby waves with approximately zonal crests. Energy spectra of the flows in the wavenumber space indicate that a wavenumber similar to that introduced by Rhines for turbulent flows on the beta-plane can be introduced here. The wavenumber is based on the translational speed of a vortex rat...
Nitao, J.J.
1989-11-06T23:59:59.000Z
The TOUGH code developed at Lawrence Berkeley Laboratory (LBL) is being extensively used to numerically simulate the thermal and hydrologic environment around nuclear waste packages in the unsaturated zone for the Yucca Mountain Project. At the Lawrence Livermore National Laboratory (LLNL) we have rewritten approximately 80 percent of the TOUGH code to increase its speed and incorporate new options. The geometry of many problems requires large numbers of computational elements elements in order to realistically model detailed physical phenomena, and, as a result, large amounts of computer time are needed. In order to increase the speed of the code we have incorporated fast linear equation solvers, vectorization of substantial portions of code, improved automatic time stepping, and implementation of table look-up for the steam table properties. These enhancements have increased the speed of the code for typical problems by a factor of 20 on the Cray 2 computer. In addition to the increase in computational efficiency we have added several options: vapor pressure lowering; equivalent continuum treatments of fractures; energy and material volumetric, mass and flux accounting; and Stefan-Boltzmann radiative heat transfer. 5 refs.
Xu, Chuanfu, E-mail: xuchuanfu@nudt.edu.cn [College of Computer Science, National University of Defense Technology, Changsha 410073 (China); Deng, Xiaogang; Zhang, Lilun [College of Computer Science, National University of Defense Technology, Changsha 410073 (China); Fang, Jianbin [Parallel and Distributed Systems Group, Delft University of Technology, Delft 2628CD (Netherlands); Wang, Guangxue; Jiang, Yi [State Key Laboratory of Aerodynamics, P.O. Box 211, Mianyang 621000 (China); Cao, Wei; Che, Yonggang; Wang, Yongxian; Wang, Zhenghua; Liu, Wei; Cheng, Xinghua [College of Computer Science, National University of Defense Technology, Changsha 410073 (China)
2014-12-01T23:59:59.000Z
Programming and optimizing complex, real-world CFD codes on current many-core accelerated HPC systems is very challenging, especially when collaborating CPUs and accelerators to fully tap the potential of heterogeneous systems. In this paper, with a tri-level hybrid and heterogeneous programming model using MPI + OpenMP + CUDA, we port and optimize our high-order multi-block structured CFD software HOSTA on the GPU-accelerated TianHe-1A supercomputer. HOSTA adopts two self-developed high-order compact definite difference schemes WCNS and HDCS that can simulate flows with complex geometries. We present a dual-level parallelization scheme for efficient multi-block computation on GPUs and perform particular kernel optimizations for high-order CFD schemes. The GPU-only approach achieves a speedup of about 1.3 when comparing one Tesla M2050 GPU with two Xeon X5670 CPUs. To achieve a greater speedup, we collaborate CPU and GPU for HOSTA instead of using a naive GPU-only approach. We present a novel scheme to balance the loads between the store-poor GPU and the store-rich CPU. Taking CPU and GPU load balance into account, we improve the maximum simulation problem size per TianHe-1A node for HOSTA by 2.3×, meanwhile the collaborative approach can improve the performance by around 45% compared to the GPU-only approach. Further, to scale HOSTA on TianHe-1A, we propose a gather/scatter optimization to minimize PCI-e data transfer times for ghost and singularity data of 3D grid blocks, and overlap the collaborative computation and communication as far as possible using some advanced CUDA and MPI features. Scalability tests show that HOSTA can achieve a parallel efficiency of above 60% on 1024 TianHe-1A nodes. With our method, we have successfully simulated an EET high-lift airfoil configuration containing 800M cells and China's large civil airplane configuration containing 150M cells. To our best knowledge, those are the largest-scale CPU–GPU collaborative simulations that solve realistic CFD problems with both complex configurations and high-order schemes.
Non-linear transformer modeling and simulation
Archer, W.E.; Deveney, M.F.; Nagel, R.L.
1994-08-01T23:59:59.000Z
Transformers models for simulation with Pspice and Analogy`s Saber are being developed using experimental B-H Loop and network analyzer measurements. The models are evaluated for accuracy and convergence using several test circuits. Results are presented which demonstrate the effects on circuit performance from magnetic core losses eddy currents and mechanical stress on the magnetic cores.
Simulating Collisions for Hydrokinetic Turbines
Richmond, Marshall C.; Romero Gomez, Pedro DJ; Rakowski, Cynthia L.
2013-10-01T23:59:59.000Z
Evaluations of blade-strike on an axial-flow Marine Hydrokinetic turbine were conducted using a conventional methodology as well as an alternative modeling approach proposed in the present document. The proposed methodology integrates the following components into a Computa- tional Fluid Dynamics (CFD) model: (i) advanced eddy-resolving flow simulations, (ii) ambient turbulence based on field data, (iii) moving turbine blades in highly transient flows, and (iv) Lagrangian particles to mimic the potential fish pathways. The sensitivity of blade-strike prob- ability to the following conditions was also evaluated: (i) to the turbulent environment, (ii) to fish size and (iii) to mean stream flow velocity. The proposed methodology provided fraction of collisions and offered the capability of analyzing the causal relationships between the flow envi- ronment and resulting strikes on rotating blades. Overall, the conventional methodology largely overestimates the probability of strike, and lacks the ability to produce potential fish and aquatic biota trajectories as they interact with the rotating turbine. By using a set of experimental corre- lations of exposure-response of living fish colliding on moving blades, the occurrence, frequency and intensity of the particle collisions was next used to calculate the survival rate of fish crossing the MHK turbine. This step indicated survival rates always greater than 98%. Although the proposed CFD framework is computationally more expensive, it provides the advantage of evaluating multiple mechanisms of stress and injury of hydrokinetic turbine devices on fish.
On the self-sustained nature of large-scale motions in turbulent Couette flow
Rawat, Subhandu; Hwang, Yongyun; Rincon, François
2015-01-01T23:59:59.000Z
Large-scale motions in wall-bounded turbulent flows are frequently interpreted as resulting from an aggregation process of smaller-scale structures. Here, we explore the alternative possibility that such large-scale motions are themselves self-sustained and do not draw their energy from smaller-scale turbulent motions activated in buffer layers. To this end, it is first shown that large-scale motions in turbulent Couette flow at Re=2150 self-sustain even when active processes at smaller scales are artificially quenched by increasing the Smagorinsky constant Cs in large eddy simulations. These results are in agreement with earlier results on pressure driven turbulent channels. We further investigate the nature of the large-scale coherent motions by computing upper and lower-branch nonlinear steady solutions of the filtered (LES) equations with a Newton-Krylov solver,and find that they are connected by a saddle-node bifurcation at large values of Cs. Upper branch solutions for the filtered large scale motions a...
Alcian Blue Cartilage Staining Beatrice Jegalian & Eddy M. De Robertis
De Robertis, Eddy M.
Alcian Blue Cartilage Staining Beatrice Jegalian & Eddy M. De Robertis (Cell 71, 901-910, 1992) 1 will require more time) in 0.05% Alcian blue 8GX (Fisher) in 5% acetic acid. 6. Wash embryos in 5% acetic acid Alcian Blue 8 g NaCl 0.05% Alcian blue 8GX .2 g KCl 5% acetic acid 1.44 g Na2HPO4 water .24 g KH2PO4 800
Automated detection and location of indications in eddy current signals
Brudnoy, David M. (Albany, NY); Oppenlander, Jane E. (Burnt Hills, NY); Levy, Arthur J. (Schenectady, NY)
2000-01-01T23:59:59.000Z
A computer implemented information extraction process that locates and identifies eddy current signal features in digital point-ordered signals, signals representing data from inspection of test materials, by enhancing the signal features relative to signal noise, detecting features of the signals, verifying the location of the signal features that can be known in advance, and outputting information about the identity and location of all detected signal features.
Eddy current scanning of niobium for SRF cavities at Fermilab
Boffo, C.; Bauer, P.; Foley, M.; Antoine, C.; Cooper, C.; /Fermilab; Brinkmann, A.; /DESY
2006-08-01T23:59:59.000Z
In the framework of SRF cavity development, Fermilab is creating the infrastructure needed for the characterization of the material used in the cavity fabrication. An important step in the characterization of ''as received'' niobium sheets is eddy current scanning. Eddy current scanning is a non-destructive technique first adopted and further developed by DESY with the purpose of checking the cavity material for subsurface defects and inclusions. Fermilab has received and further upgraded a commercial eddy current scanner previously used for the SNS project. This scanner is now used daily to scan the niobium sheets for the Fermilab third harmonic, the ILC, and the Proton Driver cavities. After optical inspection, more than 400 squares and disks have been scanned and when necessary checked at the optical and electron microscopes, anodized, or measured with profilometers looking for surface imperfections that might limit the performance of the cavities. This paper gives a status report on the scanning results obtained so far, including a discussion of the classification of signals being detected.
Method and apparatus for correcting eddy current signal voltage for temperature effects
Kustra, Thomas A. (N. Huntingdon, PA); Caffarel, Alfred J. (Pittsburgh, PA)
1990-01-01T23:59:59.000Z
An apparatus and method for measuring physical characteristics of an electrically conductive material by the use of eddy-current techniques and compensating measurement errors caused by changes in temperature includes a switching arrangement connected between primary and reference coils of an eddy-current probe which allows the probe to be selectively connected between an eddy current output oscilloscope and a digital ohm-meter for measuring the resistances of the primary and reference coils substantially at the time of eddy current measurement. In this way, changes in resistance due to temperature effects can be completely taken into account in determining the true error in the eddy current measurement. The true error can consequently be converted into an equivalent eddy current measurement correction.
Eddy current probe with foil sensor mounted on flexible probe tip and method of use
Viertl, John R. M. (Niskayuna, NY); Lee, Martin K. (Niskayuna, NY)
2001-01-01T23:59:59.000Z
A pair of copper coils are embedded in the foil strip. A first coil of the pair generates an electromagnetic field that induces eddy currents on the surface, and the second coil carries a current influenced by the eddy currents on the surface. The currents in the second coil are analyzed to obtain information on the surface eddy currents. An eddy current probe has a metal housing having a tip that is covered by a flexible conductive foil strip. The foil strip is mounted on a deformable nose at the probe tip so that the strip and coils will conform to the surface to which they are applied.
Direct numerical simulation of turbulent reacting flows
Chen, J.H. [Sandia National Laboratories, Livermore, CA (United States)
1993-12-01T23:59:59.000Z
The development of turbulent combustion models that reflect some of the most important characteristics of turbulent reacting flows requires knowledge about the behavior of key quantities in well defined combustion regimes. In turbulent flames, the coupling between the turbulence and the chemistry is so strong in certain regimes that is is very difficult to isolate the role played by one individual phenomenon. Direct numerical simulation (DNS) is an extremely useful tool to study in detail the turbulence-chemistry interactions in certain well defined regimes. Globally, non-premixed flames are controlled by two limiting cases: the fast chemistry limit, where the turbulent fluctuations. In between these two limits, finite-rate chemical effects are important and the turbulence interacts strongly with the chemical processes. This regime is important because industrial burners operate in regimes in which, locally the flame undergoes extinction, or is at least in some nonequilibrium condition. Furthermore, these nonequilibrium conditions strongly influence the production of pollutants. To quantify the finite-rate chemistry effect, direct numerical simulations are performed to study the interaction between an initially laminar non-premixed flame and a three-dimensional field of homogeneous isotropic decaying turbulence. Emphasis is placed on the dynamics of extinction and on transient effects on the fine scale mixing process. Differential molecular diffusion among species is also examined with this approach, both for nonreacting and reacting situations. To address the problem of large-scale mixing and to examine the effects of mean shear, efforts are underway to perform large eddy simulations of round three-dimensional jets.
.org/EducationResources/CommunityCollege/EddyCurrents/Introduction/IntroductiontoET.htm, 2 Calderwood, C & Nelligan, T. Eddy Current Testing. Olympus Corporation,2011.[Online]. Available at: http://www.olympus-ims.com/en/eddycurrenttesting/ , 3 Santandrea. L., & Le Bihan, Y. Using COMSOL-Multiphysics in an Eddy Current Non
Methods of and apparatus for levitating an eddy current probe
Stone, William J. (Kansas City, MO)
1988-05-03T23:59:59.000Z
An eddy current probe is supported against the force of gravity with an air earing while being urged horizontally toward the specimen being examined by a spring and displaced horizontally against the force of the spring pneumatically. The pneumatic displacement is accomplished by flowing air between a plenum chamber fixed with respect to the probe and the surface of the specimen. In this way, the surface of the specimen can be examined without making mechanical contact therewith while precisely controlling the distance at which the probe stands-off from the surface of the specimen.
Eddy current system for inspection of train hollow axles
Chady, Tomasz; Psuj, Grzegorz; Sikora, Ryszard; Kowalczyk, Jacek; Spychalski, Ireneusz [Department of Electrical and Computer Engineering, Faculty of Electrical Engineering, West Pomeranian University of Technology, Szczecin (Poland)
2014-02-18T23:59:59.000Z
The structural integrity of wheelsets used in rolling stock is of great importance to the safety. In this paper, electromagnetic system with an eddy current transducer suitable for the inspection of hollow axles have been presented. The transducer was developed to detect surface braking defects having depth not smaller than 0.5 mm. Ultrasound technique can be utilized to inspect the whole axle, but it is not sufficiently sensitive to shallow defects located close to the surface. Therefore, the electromagnetic technique is proposed to detect surface breaking cracks that cannot be detected by ultrasonic technique.
The Role of Eddy-Tansport in the Thermohaline Circulation
Dr. Paola Cessi
2011-11-17T23:59:59.000Z
Several research themes were developed during the course of this project. (1) Low-frequency oceanic varibility; (2) The role of eddies in the Antarctic Circumpolar Current (ACC) region; (3) Deep stratification and the overturning circulation. The key findings were as follows: (1) The stratification below the main thermocline (at about 500m) is determined in the circumpolar region and then communicated to the enclosed portions of the oceans through the overturning circulation. (2) An Atlantic pole-to-pole overturning circulation can be maintained with very small interior mixing as long as surface buoyancy values are shared between the northern North Atlantic and the ACC region.
Eddy County, North Dakota: Energy Resources | 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 aCentrothermDepew, New York: EnergyMesa Geothermal AreaEcoGrid EUEddy County, New Mexico: EnergyEddy
Extremely short impulse eddy current system for titanium and inconel samples testing
Chady, T.; Frankowski, P. [Faculty of Electrical Engineering, West Pomeranian University of Technology, Sikorskiego 37, 70-313 Szczecin (Poland)
2011-06-23T23:59:59.000Z
This paper presents a new system for eddy current testing. The system enables tests with very short current impulses. Therefore, the frequency spectrum of the excitation signal is very wide. In this paper, a study of eddy current differential transducer for testing titanium element is also presented.
Ferrari, Raffaele
of the Antarctic Circumpolar Current, despite enhanced values of eddy kinetic energy. The expression in the core of the Antarctic Circumpolar Current or on its flanks. A simple expression is derived statistics. This novel expression predicts suppression of the cross-jet eddy diffusivity in the core
Influence of a cyclonic eddy on microheterotroph biomass and carbon export in the lee of Hawaii
Hawai'i at Manoa, University of
Influence of a cyclonic eddy on microheterotroph biomass and carbon export in the lee of Hawaii-derived carbon export rates within the eddy were 2 to 3 times higher than those observed for adjacent waters export in the lee of Hawaii, Geophys. Res. Lett., 30(6), 1318, doi:10.1029/2002GL016393, 2003. 1
Qiu, Bo
Eddy-Induced Heat Transport in the Subtropical North Pacific from Argo, TMI, and Altimetry transport induced by mesoscale oceanic eddies is estimated by combining satellite- derived sea surface temperaturesalinity data. In the North Pacific Ocean subtropical gyre, warm (cold) temperature anomalies
Hot-cell design considerations for interfacing eddy-current systems
Franklin, E.M.; Webb, J.P.; Larson, J.M.
1985-01-01T23:59:59.000Z
The Hot Fuel Examination Facility/North conducts remote eddy-current examination of irradiated fuel elements. Applications include cladding breach detection and irradiation-induced ferrite examination. The seccussful use of remote eddy-current techniques is achieved by applying basic test parameters and interfacing considerations. These include impedance matching, operating frequency, and feedthrough considerations.
Theory of thin-skin eddy-current interaction with surface cracks N. Harfielda)
Bowler, John R.
; accepted for publication 14 July 1997 Eddy-current non-destructive evaluation is commonly performed Institute of Physics. S0021-8979 97 06920-X I. INTRODUCTION In eddy-current non-destructive evaluation NDE-frequency testing of non-magnetic materials. The permeability of the material has a strong influence
Oceanic eddy formation and propagation southwest of Taiwan Feng Nan,1,2
Maine, University of
Oceanic eddy formation and propagation southwest of Taiwan Feng Nan,1,2 Huijie Xue,2 Peng Xiu,2 Fei October 2011; published 31 December 2011. [1] Oceanic eddies are active and energetic southwest of Taiwan, the Kuroshio Current Loop (KCL) appears southwest of Taiwan more frequently than in other seasons, and ACEs
Mesoscale eddies northeast of the Hawaiian archipelago from satellite altimeter observations
Qiu, Bo
Mesoscale eddies northeast of the Hawaiian archipelago from satellite altimeter observations; published 16 March 2010. [1] Enhanced mesoscale eddy activity northeast of the Hawaiian archipelago by 5° longitude subregions revealed the dominant mesoscale periods ranging from 90 days near 18°N
Mesoscale eddies in the northeastern Pacific tropical-subtropical transition zone: Statistical February 2012; revised 24 August 2012; accepted 6 September 2012; published 24 October 2012. [1] Mesoscale cycle. Although mesoscale eddies in these areas have been previously reported, this study provides
Monsoon surges trigger oceanic eddy formation and propagation in the lee of the Philippine Islands
with eddies that form in the lee of the Cabo Verde and Canary Islands [Chavanne et al., 2002; Sangra et al., 2007]. The Hawaii, Cabo Verde and Canary Islands are located in the trades where winds have typicalMonsoon surges trigger oceanic eddy formation and propagation in the lee of the Philippine Islands
Anticyclonic and cyclonic eddies of subtropical origin in the subantarctic zone south of Africa
Boyer, Edmond
that the meridional propagation of mesoscale eddies at distinct sectors of the Subtropical Front (STF), such as those with this view, Dencausse et al. [2011] recently observed that, due to the intense mesoscale activity interval appears as a preferential pathway for mesoscale structures. Here, indeed, warm eddies
rights reserved. Keywords: Eddy covariance; Information theory; Net ecosystem exchange; Gross ecosystemAn evaluation of models for partitioning eddy covariance-measured net ecosystem exchange Abstract We measured net ecosystem CO2 exchange (NEE) using the eddy covariance (EC) technique for 4 years
RodrÃguez, Rodolfo
Analysis of a FEM-BEM model posed on the conducting domain for the time-dependent eddy currentÂ´atica, Universidad de ConcepciÂ´on, Casilla 160-C, Concepcion, Chile. Abstract The three-dimensional eddy current time. Keywords: Boundary elements; eddy current problem; finite elements; time-dependent electromagnetic problem
ANALYSIS OF THE A, V -A -POTENTIAL FORMULATION FOR THE EDDY CURRENT PROBLEM IN A BOUNDED DOMAIN.
RodrÃguez, Rodolfo
ANALYSIS OF THE A, V - A - POTENTIAL FORMULATION FOR THE EDDY CURRENT PROBLEM IN A BOUNDED DOMAIN analysis of the well-known A, V - A- potential formulation for the eddy current problem. The resulting on standard nodal finite elements. Key words. eddy currents, potential formulation, well-posedness, finite
Page 1 of 31 Why does the Loop Current tend to shed more eddies in summer and winter?1
Page 1 of 31 Why does the Loop Current tend to shed more eddies in summer and winter?1 Y.-L. Chang seasonal preferences of Loop Current eddy shedding, more in summer and5 winter and less in fall and spring in virtually any21 month of the year. That the Loop Current can intrude into the Gulf and eddies can separate
Nagy, Peter B.
2006-01-01T23:59:59.000Z
NDT&E International 39 (2006) 641651 Iterative inversion method for eddy current profiling of near-dependent penetration depth, eddy current measurements are capable of mapping the near-surface depth profile-independent intrinsic electric conductivity depth profile from the frequency-dependent apparent eddy current
Bowler, John R.
IEEE TRANSACTIONS ON MAGNETICS, VOL. 36, NO. 1, JANUARY 2000 281 Thin-Skin Eddy-Current Interaction with Semielliptical and Epicyclic Cracks J. R. Bowler, Member, IEEE, and N. Harfield Abstract--Eddy-current probe current, nondestructive evaluation. I. INTRODUCTION IN EDDY-CURRENT nondestructive evaluation, cracks
RodrÃguez, Rodolfo
Numerical analysis of a finite element method for the axisymmetric eddy current model, 27002, Lugo, Spain The aim of this paper is to analyze a finite element method to solve an eddy current of the method are reported. Keywords: low-frequency harmonic Maxwell equations, eddy current problems, finite
Bowler, John R.
IEEE TRANSACTIONS ON MAGNETICS, VOL. 41, NO. 9, SEPTEMBER 2005 2455 Eddy Currents Induced the calculation of eddy currents in a two-layer conducting rod of finite length excited by a coaxial circular coil. Index Terms--Coil impedance, eddy current, eigenfunction expansion, finite rod. I. INTRODUCTION
Paris-Sud XI, Université de
Abstract -- For high-speed machines applications, eddy- current losses in the interior permanent carries out a prediction of eddy current losses in PM where the skin effect is considered. A complete by analytical method. Index Terms-- High speed, Permanent magnet machines, Eddy-currents, power losses, skin
Paris-Sud XI, Université de
1 EXPERIMENTAL VALIDATION OF AN EDDY CURRENT PROBE DEDICATED TO THE MULTI-FREQUENCY IMAGING OF BORE ______________________________________________________________________________________ Article info : Submitted on February 2012 Published on October 2012 Key words : Eddy currents, non dedicated to the eddy current imaging of sub-millimetric surface breaking defects appearing in bore holes
Finite element methods for 3D eddy current prob-lems in bounded domains subject to realistic
RodrÃguez, Rodolfo
Finite element methods for 3D eddy current prob- lems in bounded domains subject to realistic techniques to approximate eddy current prob- lems. The focus of the article is on the analysis of weak]), magnetostatics ([59, 60, 80, 81, 109, 110, 114]), eddy current ([1, 2, 3, 6, 7, 8, 9, 19, 20, 21, 23, 24, 25, 26
On The Use of Eddy Current Brakes as Tunable, Fast Turn-On Viscous Dampers For Haptic Rendering
Hayward, Vincent
On The Use of Eddy Current Brakes as Tunable, Fast Turn-On Viscous Dampers For Haptic RenderingGill University, Montr´eal, Canada ABSTRACT We describe the use of eddy current brakes as fast turn-on, tunable, linear dampers for haptic rendering using a prototype haptic device outfitted with eddy current brakes
Eddy-current probe impedance due to a volumetric flaw J. R. Bowler and S. A. Jenkins
Bowler, John R.
Eddy-current probe impedance due to a volumetric flaw J. R. Bowler and S. A. Jenkins University 25 January 1991) Eddy current induced in a metal by a coil carrying an alternating current may, or inclusions. In eddy-current nondestructive evaluation, defectsare commonly sensedby a change of the coil
STUDY FOR THE DESIGN OF AN EDDY CURRENT ARRAY PROBE FOR THE IMAGING OF AERONAUTICAL FASTENER HOLES
Paris-Sud XI, Université de
STUDY FOR THE DESIGN OF AN EDDY CURRENT ARRAY PROBE FOR THE IMAGING OF AERONAUTICAL FASTENER HOLES Wilson, 94230 Cachan France (joubert@satie.ens-cachan.fr) Abstract: The design of an eddy current imaging, eddy currents, imaging probe, finite element modelling, pickup coil array, printed-circuit- board coil
Two-dimensional calculation of eddy currents on external conducting walls induced by low-n external 1997; accepted 8 December 1997 The results of two-dimensional calculations of eddy currents induced on external conducting walls surrounding a tokamak are reported. The computed eddy currents are generated
Nagy, Peter B.
2007-01-01T23:59:59.000Z
NDT&E International 40 (2007) 555565 Lift-off effect in high-frequency eddy current conductivity online 12 June 2007 Abstract Precision eddy current measurements have been shown to be capable, the eddy current inspection frequency has to be as high as 5080 MHz. Unfortunately, spurious self
Eddy current residual stress profiling in surface-treated engine alloys Bassam A. Abu-Nabaha1
Nagy, Peter B.
Eddy current residual stress profiling in surface-treated engine alloys Bassam A. Abu-Nabaha1 version received 3 June 2008 ) Recent research results indicate that eddy current conductivity profile is calculated from the measured frequency-dependent apparent eddy current conductivity spectrum
MUSIC-TYPE ALGORITHM FOR EDDY-CURRENT NONDESTRUC-TIVE EVALUATION OF SMALL DEFECTS IN METAL PLATES
Paris-Sud XI, Université de
MUSIC-TYPE ALGORITHM FOR EDDY-CURRENT NONDESTRUC- TIVE EVALUATION OF SMALL DEFECTS IN METAL PLATES Eddy-Current nondestructive evaluation of metal plates is of interest in a wide range of applications in the lower frequency band (kHz) for eddy-current testing, to retrieve small void defects inside a conducting
Hua, Yingbo
. 451 Eddy Current Tomography for Metal Solidification Imaging Minh H. Pham* , Yingbo Hua* , Neil B of molten metal inside a pipe by eddy currents. A complete mathematical model is developed which reveals functions in multiple layered media. Keywords: eddy current tomography, electromagnetic field, numerical
Ida, Nathan
746 IEEE TRANSACTIONS ON MAGNETICS, VOL. 36, NO. 4, JULY 2000 Solving 3D Eddy Current ProblemsD eddy current prob- lems. The asymmetry of the facet related functions in the edge el- ement basis- ments is compared through an example. Index Terms--Eddy currents, finite element modeling, second order
ccsd-00085042,version1-11Jul2006 A Two-dimensional eddy current model using thin
Paris-Sud XI, Université de
ccsd-00085042,version1-11Jul2006 A Two-dimensional eddy current model using thin inductors Youcef a mathematical model for eddy currents in two dimensional geometries where the conductors are thin domains. We Mathematical modelling of eddy current problems often involves multiple conductors with various sizes
Zakharov, Leonid E.
web page: http://w3.pppl.gov/~ zakharov Equilibrium reconstruction in eddy current environment and small size tokamaks the eddy currents in the passive structures affect both the interpretation the time history of the discharge and sig nals, mitigates uncertainties associated with the eddy currents
Kidston, Joseph
in the atmospheric eddy length scale may cause a poleward shift of the midlatitude jet streams is addressed are a net source of baroclinic eddies, and hence the eddy-driven jet stream may shift poleward in these experiments, rather than vice versa. 1. Introduction a. Jet stream movement There is evidence of a poleward
Deep-Sea Research I 53 (2006) 17181728 A North Atlantic deep-water eddy in the
Miami, University of
2006-01-01T23:59:59.000Z
Deep-Sea Research I 53 (2006) 17181728 A North Atlantic deep-water eddy in the Agulhas Current the deep waters, pinching off an eddy, which later detached from the slope current and was carried. Keywords: Circulation; Indian Ocean; Boundary currents; Agulhas Current; Deep water; Oceanic eddies 1
Tandon, Amit
Segmentation and Tracking of Mesoscale Eddies in Numeric Ocean Models Vishal Sood, Bin John suggested that the mesoscale eddies and mesoscale features play a strong role in carrying heat poleward oceanographers an invaluable tool to assess mesoscale eddies and the Lagrangian characteristics of this mesoscale
Garfinkel, Chaim I.
Barotropic Impacts of Surface Friction on Eddy Kinetic Energy and Momentum Fluxes: An Alternative energy decreases, a response that is inconsistent with the conventional barotropic governor mechanism on eddy momentum fluxes and eddy kinetic energy. Analysis of the pseudomomentum budget shows
Anatomy and evolution of a cyclonic mesoscale eddy observed in the northeastern Pacific tropical and evolution of a cyclonic mesoscale eddy observed in the northeastern Pacific tropical-subtropical transition zone, J. Geophys. Res. Oceans, 118, doi:10.1002/ 2013JC009339. 1. Introduction [2] Mesoscale eddy
INCITE Projects 2012 INCITE Projects
Kemner, Ken
: 4 Million Hours Large-Eddy Simulation of Two-Phase Flow Combustion in Gas Turbines Thierry Poinsot
SeyedHosseinHezaveh 410-662-2787 | shezaveh@princeton.edu
Bou-Zeid, Elie
research area: Large eddy simulations of Vertical Axis Wind Turbines M.Sc. | 2008-2011 | Sharif University://powerbox.princeton.edu/Home #12;Page 2 Conference Hezaveh S.H. and Bou-Zeid E. "Large eddy simulations of vertical axis wind Research Interests Hybrid Wind Turbine Design Computational Mechanics Green Energy Large Eddy Simulations
Wadley, Haydn
permission. Eddy current sensing of vertical Bridgman semiconductor crystal growth Dharmasena, Kumar Pradeepa
Hickey, Barbara
Current. Results from three years of field studies5 demonstrate that the eddy increases in spatial extent-driven currents in the surface Ekman12 layer cause the eddy to be "leaky" on its southern perimeter. Eddy surfaceInfluences of the Juan de Fuca Eddy on circulation, nutrients, and phytoplankton1 production
Hua, Yingbo
2000-01-01T23:59:59.000Z
the solidification of molten metal by eddy currents: I Minh H Pham, Yingbo Hua and Neil B Gray The Department@ee.mu.oz.au Received 27 May 1999, in final form 20 December 1999 Abstract. This paper presents an eddy-current for this imaging task other than that of eddy currents. The eddy-current technique is a nondestructive technique
Wadley, Haydn
permission. Eddy current sensing of cadmium zinc telluride crystal growth Choi, Byoung-Woo William Pro
Interannual variability of summer biochemical enhancement in relation to mesoscale eddies the 1300-km-long eastern shelf break accompanied by a mesoscale eddy field (Okkonen, 2001a). Eddies occur., 2002). Mesoscale eddies, which penetrate to depths of at least 1000 m (Roden, 1995; Mizobata et al
Eddy PV Fluxes in the Kuroshio Extension at 144o-148oE Stuart P. Bishop* and D. Randolph Wa6s#
Rhode Island, University of
km Eddy PV Fluxes in the Kuroshio Extension at 144o-148oE Stuart P A. IntroducCon D. Divergent Vs. RotaConal Eddy PV Fluxes E. Eddy Growth G. STMW ModificaCon: SchemaCc Summary C. Time-Mean PV EquaCon & Eddy PV Flux B
Cremers, Daniel
, Eddy Ilg, Philip H¨ausser, Caner Hazirbas¸, Vladimir Golkov University of Freiburg Technical University
The role of large eddy fluctuations in the Madison Dynamo Experiment
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(Million Cubic Feet) Oregon (Including Vehicle Fuel) (MillionStructural Basis of WntSupportB 18B()The FiveRevised -SandiaTheThecombined Î½TheTheMHDLARGE
Impact of mesoscale eddies on water transport between the Pacific Ocean and the Bering Sea
Prants, S V; Budyansky, M V; Uleysky, M Yu
2013-01-01T23:59:59.000Z
Sea surface height anomalies observed by satellites in 1993--2012 are combined with simulation and observations by surface drifters and Argo floats to study water flow pattern in the Near Strait (NS) connected the Pacific Ocean with the Bering Sea. Daily Lagrangian latitudinal maps, computed with the AVISO surface velocity field, and calculation of the transport across the strait show that the flow through the NS is highly variable and controlled by mesoscale and submesoscale eddies in the area. On the seasonal scale, the flux through the western part of the NR is negatively correlated with the flux through its eastern part ($r=-0.93$). On the interannual time scale, a significant positive correlation ($r=0.72$) is diagnosed between the NS transport and the wind stress in winter. Increased southward component of the wind stress decreases the northward water transport through the strait. Positive wind stress curl over the strait area in winter--spring generates the cyclonic circulation and thereby enhances the...
Ko, Ray T.; Blodgett, Mark P. [Metals, Ceramics, and NDE Division, Air Force Research Laboratory, Wright-Patterson Air Force Base, Dayton, Ohio 45433 (United States); Sathish, Shamachary; Boehnlein, Thomas R. [Structural Integrity Division, University of Dayton Research Institute, 300 College Park, Dayton, Ohio 45469-0120 (United States)
2008-02-28T23:59:59.000Z
The shot peening intensity of nickel base materials has been examined with an innovative eddy current measurement. The goal is to provide a nondestructive tool to quantitatively evaluate the surface conditions after shot peening. Traditionally, the residual stress caused by the shot peening process can be examined by X-ray diffraction. Recent eddy current works have shown promising results in evaluating the small conductivity variation due to the residual stress. This study explores the feasibility of utilizing the cable which connects to a network analyzer and a conventional eddy current probe to monitor the surface conditions due to the shot peening.
Computer programs for eddy-current defect studies
Pate, J. R.; Dodd, C. V. [Oak Ridge National Lab., TN (USA)
1990-06-01T23:59:59.000Z
Several computer programs to aid in the design of eddy-current tests and probes have been written. The programs, written in Fortran, deal in various ways with the response to defects exhibited by four types of probes: the pancake probe, the reflection probe, the circumferential boreside probe, and the circumferential encircling probe. Programs are included which calculate the impedance or voltage change in a coil due to a defect, which calculate and plot the defect sensitivity factor of a coil, and which invert calculated or experimental readings to obtain the size of a defect. The theory upon which the programs are based is the Burrows point defect theory, and thus the calculations of the programs will be more accurate for small defects. 6 refs., 21 figs.
Workshops and problems for benchmarking eddy current codes
Turner, L.R.; Davey, K.; Ida, N.; Rodger, D.; Kameari, A.; Bossavit, A.; Emson, C.R.I.
1988-08-01T23:59:59.000Z
A series of six workshops was held in 1986 and 1987 to compare eddy current codes, using six benchmark problems. The problems included transient and steady-state ac magnetic fields, close and far boundary conditions, magnetic and non-magnetic materials. All the problems were based either on experiments or on geometries that can be solved analytically. The workshops and solutions to the problems are described. Results show that many different methods and formulations give satisfactory solutions, and that in many cases reduced dimensionality or coarse discretization can give acceptable results while reducing the computer time required. A second two-year series of TEAM (Testing Electromagnetic Analysis Methods) workshops, using six more problems, is underway. 12 refs., 15 figs., 4 tabs.
Eddy Current Examination of Spent Nuclear Fuel Canister Closure Welds
Arthur D. Watkins; Dennis C. Kunerth; Timothy R. McJunkin
2006-04-01T23:59:59.000Z
The National Spent Nuclear Fuel Program (NSNFP) has developed standardized DOE SNF canisters for handling and interim storage of SNF at various DOE sites as well as SNF transport to and SNF handling and disposal at the repository. The final closure weld of the canister will be produced remotely in a hot cell after loading and must meet American Society of Mechanical Engineers (ASME) Section III, Division 3 code requirements thereby requiring volumetric and surface nondestructive evaluation to verify integrity. This paper discusses the use of eddy current testing (ET) to perform surface examination of the completed welds and repair cavities. Descriptions of integrated remote welding/inspection system and how the equipment is intended function will also be discussed.
Modeling of transformers using circuit simulators
Archer, W.E.; Deveney, M.F.; Nagel, R.L.
1994-07-01T23:59:59.000Z
Transformers of two different designs; and unencapsulated pot core and an encapsulated toroidal core have been modeled for circuit analysis with circuit simulation tools. We selected MicroSim`s PSPICE and Anology`s SABER as the simulation tools and used experimental BH Loop and network analyzer measurements to generate the needed input data. The models are compared for accuracy and convergence using the circuit simulators. Results are presented which demonstrate the effects on circuit performance from magnetic core losses, eddy currents, and mechanical stress on the magnetic cores.
Eddy covariance flux measurements of pollutant gases in urban Mexico City
Velasco, Erik
Eddy covariance (EC) flux measurements of the atmosphere/surface exchange of gases over an urban area are a direct way to improve and evaluate emissions inventories, and, in turn, to better understand urban atmospheric ...
Shuckburgh, Emily
A diagnostic framework is presented, based on the Nakamura effective diffusivity, to investigate the regional variation in eddy diffusivity. Comparison of three different diffusivity calculations enables the effects of ...
Enhancement of Mesoscale Eddy Stirring at Steering Levels in the Southern Ocean
Marshall, John C.
Meridional cross sections of effective diffusivity in the Southern Ocean are presented and discussed. The effective diffusivity, K[subscript eff], characterizes the rate at which mesoscale eddies stir properties on interior ...
EDDY CURRENT INVERSION AND ESTIMATION METRICS FOR EVALUATING THERMAL BARRIER COATINGS
Sabbagh, Harold A.; Murphy, R. Kim; Sabbagh, Elias H. [Victor Technologies LLC, Bloomington, IN 47401 (United States); Knopp, Jeremy S. [Air Force Research Laboratory, Wright-Patterson AFB, OH 45433 (United States); Aldrin, John C. [Computational Tools, Gurnee, IL 60031 (United States); Nyenhuis, John [Dept. of Electric Computer Engineering, Purdue University, West Lafayette, IN (United States)
2010-02-22T23:59:59.000Z
In this paper, sophisticated eddy-current techniques incorporating model-based inverse methods were successfully demonstrated to measure the thickness and remaining-life of high-temperature coatings. To further assure the performance of these inverse methods, several estimation metrics including Fisher Information, Cramer-Rao Lower Bound (CRLB), covariance, and singular value decomposition (SVD) are introduced. The connections and utility of these metrics are illustrated in the design of eddy current methods for estimating layer thickness, conductivity and probe liftoff.
Parametric Studies and Optimization of Eddy Current Techniques through Computer Modeling
Todorov, E. I. [EWI, Engineering and NDE, 1250 Arthur E. Adams Dr., Columbus, OH 43221-3585 (United States)
2007-03-21T23:59:59.000Z
The paper demonstrates the use of computer models for parametric studies and optimization of surface and subsurface eddy current techniques. The study with high-frequency probe investigates the effect of eddy current frequency and probe shape on the detectability of flaws in the steel substrate. The low-frequency sliding probe study addresses the effect of conductivity between the fastener and the hole, frequency and coil separation distance on detectability of flaws in subsurface layers.
Method for removal of random noise in eddy-current testing system
Levy, Arthur J. (Schenectady, NY)
1995-01-01T23:59:59.000Z
Eddy-current response voltages, generated during inspection of metallic structures for anomalies, are often replete with noise. Therefore, analysis of the inspection data and results is difficult or near impossible, resulting in inconsistent or unreliable evaluation of the structure. This invention processes the eddy-current response voltage, removing the effect of random noise, to allow proper identification of anomalies within and associated with the structure.
Asaad, Sameh W; Bellofatto, Ralph E; Brezzo, Bernard; Haymes, Charles L; Kapur, Mohit; Parker, Benjamin D; Roewer, Thomas; Tierno, Jose A
2014-01-28T23:59:59.000Z
A plurality of target field programmable gate arrays are interconnected in accordance with a connection topology and map portions of a target system. A control module is coupled to the plurality of target field programmable gate arrays. A balanced clock distribution network is configured to distribute a reference clock signal, and a balanced reset distribution network is coupled to the control module and configured to distribute a reset signal to the plurality of target field programmable gate arrays. The control module and the balanced reset distribution network are cooperatively configured to initiate and control a simulation of the target system with the plurality of target field programmable gate arrays. A plurality of local clock control state machines reside in the target field programmable gate arrays. The local clock state machines are configured to generate a set of synchronized free-running and stoppable clocks to maintain cycle-accurate and cycle-reproducible execution of the simulation of the target system. A method is also provided.