Large Eddy Simulations of extinction
Ayache, S.; Garmory, A.; Tyliszczak, A.; Mastorakos, E.
2012-08-29
-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...
Vehicle Technologies Office Merit Review 2015: Large Eddy Simulation...
Office of Environmental Management (EM)
Large Eddy Simulation (LES) Applied to Advanced Engine Combustion Research Vehicle Technologies Office Merit Review 2015: Large Eddy Simulation (LES) Applied to Advanced Engine...
Large-Eddy Simulation for Green Energy and Propulsion Systems...
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
Large-Eddy Simulation for Green Energy and Propulsion Systems PI Name: Umesh Paliath PI Email: paliath@ge.com Institution: General Electric Allocation Program: INCITE Allocation...
Large Eddy Simulation (LES) Applied to Advanced Engine Combustion...
Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site
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 of starting buoyant jets
Law, Adrian Wing-Keung
A series of Large Eddy Simulations (LES) are performed to investigate the penetration of starting buoyant jets. The LES code is first validated by comparing simulation results with existing experimental data for both steady ...
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.
2012-01-01
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.
Sandia Energy - Large Eddy Simulation (LES) of Engines
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Homesum_a_epg0_fpd_mmcf_m.xls" ,"Available from WebQuantity ofkandz-cm11 Outreach Home RoomPreservation of Fe(II)Geothermal Energy &Water Power ProgramLarge Eddy Simulation (LES) of
Sandia Energy - Large Eddy Simulation (LES) of Engines
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Homesum_a_epg0_fpd_mmcf_m.xls" ,"Available from WebQuantity ofkandz-cm11 Outreach Home RoomPreservation of Fe(II)Geothermal Energy &Water Power ProgramLarge Eddy Simulation (LES)
Large-eddy simulation of turbulent circular jet flows
Jones, S. C.; Sotiropoulos, F.; Sale, M. J.
2002-07-01
This report presents a numerical method for carrying out large-eddy simulations (LES) of turbulent free shear flows and an application of a method to simulate the flow generated by a nozzle discharging into a stagnant reservoir. The objective of the study was to elucidate the complex features of the instantaneous flow field to help interpret the results of recent biological experiments in which live fish were exposed to the jet shear zone. The fish-jet experiments were conducted at the Pacific Northwest National Laboratory (PNNL) under the auspices of the U.S. Department of Energy’s Advanced Hydropower Turbine Systems program. The experiments were designed to establish critical thresholds of shear and turbulence-induced loads to guide the development of innovative, fish-friendly hydropower turbine designs.
Hydrodynamic and hydromagnetic energy spectra from large eddy simulations
N. E. L. Haugen; A. Brandenburg
2006-06-29
Direct and large eddy simulations of hydrodynamic and hydromagnetic turbulence have been performed in an attempt to isolate artifacts from real and possibly asymptotic features in the energy spectra. It is shown that in a hydrodynamic turbulence simulation with a Smagorinsky subgrid scale model using 512^3 meshpoints two important features of the 4096^3 simulation on the Earth simulator (Kaneda et al. 2003, Phys. Fluids 15, L21) are reproduced: a k^{-0.1} correction to the inertial range with a k^{-5/3} Kolmogorov slope and the form of the bottleneck just before the dissipative subrange. Furthermore, it is shown that, while a Smagorinsky-type model for the induction equation causes an artificial and unacceptable reduction in the dynamo efficiency, hyper-resistivity yields good agreement with direct simulations. In the large-scale part of the inertial range, an excess of the spectral magnetic energy over the spectral kinetic energy is confirmed. However, a trend towards spectral equipartition at smaller scales in the inertial range can be identified. With magnetic fields, no explicit bottleneck effect is seen.
Modeling dilute sediment suspension using large-eddy simulation with a dynamic mixed model
Fringer, Oliver B.
Modeling dilute sediment suspension using large-eddy simulation with a dynamic mixed model Yi Transport of suspended sediment in high Reynolds number channel flows Re=O 600 000 is simulated using large-eddy simulation along with a dynamic-mixed model DMM . Because the modeled sediment concentration is low
Large-Eddy Simulation of the Acoustic Response of a Perforated Plate
Nicoud, Franck
Large-Eddy Simulation of the Acoustic Response of a Perforated Plate Jean Dass´e and Simon Mendez response of a multi-perforated plate submitted to normal acoustic excitation with Large-Eddy Simulation (LES). It consists in simulating an infinite perforated plate, the periodicity of the geometry allowing
Mesoscale and Large-Eddy Simulations for Wind Energy
Marjanovic, N
2011-02-22
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.
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
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 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
XLES Part II: From Extended Large Eddy Simulation to ODTLES
Glawe, Christoph; Kerstein, Alan R; Klein, Rupert
2015-01-01
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...
Large eddy simulation of unsteady lean stratified premixed combustion
Duwig, C.; Fureby, C.
2007-10-15
Premixed turbulent flame-based technologies are rapidly growing in importance, with applications to modern clean combustion devices for both power generation and aeropropulsion. However, the gain in decreasing harmful emissions might be canceled by rising combustion instabilities. Unwanted unsteady flame phenomena that might even destroy the whole device have been widely reported and are subject to intensive studies. In the present paper, we use unsteady numerical tools for simulating an unsteady and well-documented flame. Computations were performed for nonreacting, perfectly premixed and stratified premixed cases using two different numerical codes and different large-eddy-simulation-based flamelet models. Nonreacting simulations are shown to agree well with experimental data, with the LES results capturing the mean features (symmetry breaking) as well as the fluctuation level of the turbulent flow. For reacting cases, the uncertainty induced by the time-averaging technique limited the comparisons. Given an estimate of the uncertainty, the numerical results were found to reproduce well the experimental data in terms both of mean flow field and of fluctuation levels. In addition, it was found that despite relying on different assumptions/simplifications, both numerical tools lead to similar predictions, giving confidence in the results. Moreover, we studied the flame dynamics and particularly the response to a periodic pulsation. We found that above a certain excitation level, the flame dynamic changes and becomes rather insensitive to the excitation/instability amplitude. Conclusions regarding the self-growth of thermoacoustic waves were drawn. (author)
Raman, Venkat
LARGE EDDY SIMULATION/EULERIAN PROBABILITY DENSITY FUNCTION APPROACH FOR SIMULATING HYDROGEN 78712 Email: v.raman@mail.utexas.edu Scott Martin Siemens Energy Corp. Orlando, Florida Email:scott.m.martin@siemens.com ABSTRACT To describe partially-premixed combustion inside hydrogen- rich combustors, a novel quadrature
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 ...
Kogan, Yefim L.; Kogan, Zena N.; Mechem, David B.
2009-08-01
by the Cooperative Institute for Mesoscale Meteorological Studies Large-Eddy Simulation (CIMMS LES) explicit microphysics model for stratocumulus cases observed during the Atlantic Stratocumulus Transition Experiment (ASTEX) field project. The fidelity of analytic...
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.
2010-12-01
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 ...
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
2008-09-08
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.
Large-eddy simulation of lean hydrogenemethane turbulent premixed flames in the methane-
Gülder, Ömer L.
Large-eddy simulation of lean hydrogenemethane turbulent premixed flames in the methane- dominated to available experimental data. The enriched flame has 20% H2 in terms of mole fraction and lies in the methane methane flame in the methane- dominated regime. Copyright ª 2014, Hydrogen Energy Publications, LLC
Wind Energy-Related Atmospheric Boundary Layer Large-Eddy Simulation Using OpenFOAM: Preprint
Churchfield, M.J.; Vijayakumar, G.; Brasseur, J.G.; Moriarty, P.J.
2010-08-01
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).
Raman, Venkat
Large Eddy Simulation based Studies of Reacting and Non-reacting Transverse Jets in Supersonic.S. Air Force Research Laboratory, WrightPatterson Air Force Base, Ohio, 45433, USA Jet in supersonic and oxidizer .25 Here, the fuel jet issues from an injector typically mounted on the combustor walls either
Compressible Large-Eddy Simulation of Separation Control on a Wall-Mounted Hump
Colonius, Tim
additional data from pressure taps, particle image velocimetry (PIV), and oil-film flow visualization along turbulent separation bubble. The low Mach number large-eddy simulation demonstrated a good prediction of surface pressure coefficient, separation-bubble length, and velocity profiles compared with experiments
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 with colder walls is a key phenomenon in all chambers and is actually a main design constraint in gas turbines
Large-eddy Simulation of Realistic Gas Turbine Combustors , & Apte, S. V.
Apte, Sourabh V.
Large-eddy Simulation of Realistic Gas Turbine Combustors Moin, P. , & Apte, S. V. Center of reacting multiphase flows in practical gas-turbine combustion chambers involving complex physical phe specifically for gas-turbine applications. The non-dissipative, yet ro- bust numerical scheme for arbitrary
Massively-Parallel Spectral Element Large Eddy Simulation of a Ring-Type Gas Turbine Combustor
Camp, Joshua Lane
2012-07-16
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...
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
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
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
Acoustic modeling of perforated plates with bias flow for Large-Eddy Simulations
Mendez, Simon
Acoustic modeling of perforated plates with bias flow for Large-Eddy Simulations S. Mendez a,, J. D of California, Los Angeles, Los Angeles, CA 90095, USA. Abstract The study of the acoustic effect of perforated to provide data on the flow around a perforated plate and the associated acoustic damping is demonstrated
Effect of Large-Eddy Simulation Fidelity on Predicted Mechanisms of Jet Noise Reduction
Freund, Jonathan B.
the design of quieter jet engines. Continued increase of engine bypass ratios is no longer a viable option for reducing the engine's jet noise through corre- sponding reduction of the jet exhaust velocity. InsteadEffect of Large-Eddy Simulation Fidelity on Predicted Mechanisms of Jet Noise Reduction Jeonglae
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
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 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
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 turbulent flow for grid-to-rod fretting in nuclear reactors
DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)
Bakosi, J.; Christon, M. A.; Lowrie, R. B.; Pritchett-Sheats, L. A.; Nourgaliev, R. R.
2013-07-12
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 3 × 3 and 5 × 5 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 carriedmore »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 singlephase incompressible Navier-Stokes equations. The simulations explicitly resolve the large scale motions of the turbulent flow field using first principles and rely on a monotonicity-preserving numerical technique to represent the unresolved scales. Each series of simulations for the 3 × 3 and 5 × 5 rod-bundle geometries is an analysis of the flow field statistics combined with a mesh-refinement study and validation with available experimental data. Our primary focus is the time history and statistics of the forces loading the fuel rods. These hydrodynamic forces are believed to be the key player resulting in rod vibration and GTRF wear, one of the leading causes for leaking nuclear fuel which costs power utilities millions of dollars in preventive measures. As a result, we demonstrate that implicit large-eddy simulation of rod-bundle flows is a viable way to calculate the excitation forces for the GTRF problem.« less
Large Eddy Simulation studies of the effects of alignment and wind farm length
Stevens, Richard J A M; Meneveau, Charles
2014-01-01
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.
2015-04-30
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
2014-01-01
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...
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. As the market for wind energy grows, wind turbines and wind plants are becoming
Creech, Angus; Maguire, A Eoghan
2014-01-01
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
2014-01-01
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)
2010-03-15
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)
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
Jagannathan, Shriram
2012-02-14
The separation and reattachment of the suction surface boundary layer in a low pressure turbine is characterized using large-eddy simulation at Re=68,000 based on freestream velocity and suction surface length. A high pass filtered Smagorinsky model...
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 equalJ4.3 LARGE-EDDY SIMULATION ACROSS A GRID REFINEMENT INTERFACE USING EXPLICIT FILTERING
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
2013-01-01
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...
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)
2013-12-15
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.
Turbulence prediction in two- and three-dimensional bundle flows using Large Eddy Simulation
Ibrahim, Wael Abdul-Hamid
1994-01-01
to practical engineering problems such as the flow-induced vibration of steam generator tubes. A universal model for all scales of turbulence is unlikely. Thus, the influence of the large-scale structures is directly computed by LES, while the smaller eddies...
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)
2014-08-15
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.
Modifications to WRFs dynamical core to improve the treatment of moisture for large-eddy simulations
DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)
Xiao, Heng; Endo, Satoshi; Wong, May; Skamarock, William C.; Klemp, Joseph B.; Fast, Jerome D.; Gustafson, Jr., William I.; Vogelmann, Andrew; Wang, Hailong; Liu, Yangang; et al
2015-10-29
Yamaguchi and Feingold (2012) note that the cloud fields in their large-eddy simulations (LESs) of marine stratocumulus using the Weather Research and Forecasting (WRF) model exhibit a strong sensitivity to time stepping choices. In this study, we reproduce and analyze this sensitivity issue using two stratocumulus cases, one marine and one continental. Results show that (1) the sensitivity is associated with spurious motions near the moisture jump between the boundary layer and the free atmosphere, and (2) these spurious motions appear to arise from neglecting small variations in water vapor mixing ratio (qv) in the pressure gradient calculation in themore »acoustic sub-stepping portion of the integration procedure. We show that this issue is remedied in the WRF dynamical core by replacing the prognostic equation for the potential temperature ? with one for the moist potential temperature ?m=?(1+1.61qv), which allows consistent treatment of moisture in the calculation of pressure during the acoustic sub-steps. With this modification, the spurious motions and the sensitivity to the time stepping settings (i.e., the dynamic time step length and number of acoustic sub-steps) are eliminated in both of the example stratocumulus cases. In conclusion, this modification improves the applicability of WRF for LES applications, and possibly other models using similar dynamical core formulations, and also permits the use of longer time steps than in the original code.« less
Practical application of large eddy simulation to film cooling flow analysis on gas turbine airfoils
Takata, T.; Takeishi, K.; Kawata, Y.; Tsuge, A.
1999-07-01
Large eddy simulation (LES) using body-fitted coordinates is applied to solve film cooling flow on turbine blades. The turbulent model was tuned using the experimental flow field and adiabatic film cooling effectiveness measurements for a single row of holes on a flat plate surface. The results show the interaction between the main stream boundary layer and injected film cooling air generates kidney and horseshoe shaped vortices. Comparison of the temperature distribution between experimental results and present analysis has been conducted. The non-dimensional temperature distribution at x/d = 1 is dome style and quantitatively agrees with experimental results. LES was also applied to solve film cooling on a turbine airfoil. If LES was applied to solve whole flow field domain large CPU time would make the solution impractical. LES, using body-fitted coordinates, is applied to solve the non-isotropic film cooling flow near the turbine blade. The cascade flow domain, with a pitch equal to one film cooling hole spacing, is solved using {kappa}-{epsilon} model. By using such a hybrid numerical method, CPU time is reduced and numerical accuracy is insured. The analytical results show the interaction between the flow blowing through film cooling holes and mainstream on the suction and pressure surfaces of the turbine airfoil. They also show the fundamental structure of the film cooling air flow is governed by arch internal secondary flow and horseshoe vortices which have a similar structure to film cooling air flow blowing through a cooling hole on a flat plate. In the flow field, the effect of turbulent structure on curvature (relaminarization) and flow pattern, involving the interaction between main flow and the cooling jet, are clearly shown. Film cooling effectiveness on the blade surface is predicted from the results of the thermal field calculation and is compared with the test result.
DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)
Maurer, K. D.; Bohrer, G.; Ivanov, V. Y.
2014-11-27
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
A framework for the evaluation of turbulence closures used in mesoscale ocean large-eddy simulations
Graham, Jonathan Pietarila
2012-01-01
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
Large-Eddy Simulation of Maritime Deep Tropical Marat F. Khairoutdinov1
Collett Jr., Jeffrey L.
horizontal grid cell in a global climate model. The simulation is driven by large-scale thermodynamic 6 256 grid points with horizontal grid spacing of 100 m and vertical grid spacing ranging from 50 m in which cold pools are suppressed by switching off the evaporation of precipitation results in much lower
Churchfield, M. J.; Li, Y.; Moriarty, P. J.
2012-07-01
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.
Churchfield, M. J.; Li, Y.; Moriarty, P. J.
2011-07-01
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.
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
2010-10-15
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.
2013-10-01
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.
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
Turbulence prediction using the large eddy simulation method in staggered and inlined bundles
Barsamian, Hagop Raffi
1994-01-01
different geometric arrangements were used in the simulation of turbulent cross flow within rigid tube bundles. Staggered arrays were used in deep bundle simulations of two-dimensions (27,412 nodes) and three-dimensions (210,600 nodes). Comparisons were...
Ovchinnikov, Mikhail; Ackerman, Andrew; Avramov, Alex; Cheng, Anning; Fan, Jiwen; Fridlind, Ann; Ghan, Steven J.; Harrington, Jerry Y.; Hoose, Corinna; Korolev, Alexei; McFarquhar, Greg; Morrison, H.; Paukert, Marco; Savre, Julien; Shipway, Ben; Shupe, Matthew D.; Solomon, Amy; Sulia, Kara
2014-03-14
Large-eddy simulations of mixed-phase Arctic clouds by 11 different models are analyzed with the goal of improving understanding and model representation of processes controlling the evolution of these clouds. In a case based on observations from the Indirect and Semi-Direct Aerosol Campaign (ISDAC), it is found that ice number concentration, Ni, exerts significant influence on the cloud structure. Increasing Ni leads to a substantial reduction in liquid water path (LWP) and potential cloud dissipation, in agreement with earlier studies. By comparing simulations with the same microphysics coupled to different dynamical cores as well as the same dynamics coupled to different microphysics schemes, it is found that the ice water path (IWP) is mainly controlled by ice microphysics, while the inter-model differences in LWP are largely driven by physics and numerics of the dynamical cores. In contrast to previous intercomparisons, all models here use the same ice particle properties (i.e., mass-size, mass-fall speed, and mass-capacitance relationships) and a common radiation parameterization. The constrained setup exposes the importance of ice particle size distributions (PSD) in influencing cloud evolution. A clear separation in LWP and IWP predicted by models with bin and bulk microphysical treatments is documented and attributed primarily to the assumed shape of ice PSD used in bulk schemes. Compared to the bin schemes that explicitly predict the PSD, schemes assuming exponential ice PSD underestimate ice growth by vapor deposition and overestimate mass-weighted fall speed leading to an underprediction of IWP by a factor of two in the considered case.
Yue, Qing; Kahn, Brian; Xiao, Heng; Schreier, Mathias; Fetzer, E. J.; Teixeira, J.; Suselj, Kay
2013-08-16
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
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
Massively Parallel Spectral Element Large Eddy Simulation of a Turbulent Channel Using Wall Models
Rabau, Joshua I
2013-05-01
, Nek5000, and verify the method using a turbulent channel simulation. The first grid point is placed at y+ = 100, in the log-law region, for Re? = 950 and the sub-grid scales are modeled using a dynamic Smagorinski model. The results are then compared...
Large eddy simulation of supersonic combustion with application to scramjet engines
Cocks, Peter
2011-07-12
.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.
2014-12-01
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
2010-03-03
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.
2014-08-01
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.
2014-06-01
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
2015-06-19
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)
2013-10-15
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
1996-02-19
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.
Mirocha, Jeffrey D.; Kosovi?, Branko
2010-01-01
Study of the In?uence of Subsidence on the Stably Strati?eduence of the large-scale subsidence rate, S, on the stablydepth and temperature. Subsidence reduces the magnitudes of
Validation of Eddy-renewal model by numerical simulation
Garbe, Christoph S.
Validation of Eddy-renewal model by numerical simulation Li-Ping Hung1,2 , Christoph S. Garbe1, E-mail: wttsai@ncu.edu.tw Abstract. The eddy-renewal model proposes that the dominant vortical flows as the diffusivity effect in the thin diffusive sublayer beneath surface. Key Words: eddy-renewal model, numerical
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)
2014-08-15
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
2013-01-01
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)
2013-01-25
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
Nicoud, Franck
Simulation: Application to a cooled turbine blade F. Duchaine a,*, A. Corpron b , L. Pons b , V. Moureau b parameters. The coupled tool is then applied to a cooled turbine blade model where results demonstrate both walls is an important phenomenon in combustion chambers and a main design constraint in gas turbines
Model turbulent floods with the Smagorinski large eddy closure
A. J. Roberts; D. J. Georgiev; D. V. Strunin
2008-05-21
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.
Towards Robust Unstructured Turbomachinery Large Eddy Simulation
Watson, R. A.; Tucker, P. G.; Wang, Z.-N.; Yuan, X.
2015-06-18
understanding and performance. This is likely to remain the case for the immediate future. Acknowledgements This work was supported by an iCASE studentship from the Engineering and Physical Sciences Research Council, via Rolls-Royce plc. The funding from 31 both...
Large-Eddy Observation of Post-Cold-Frontal Continental Stratocumulus
Mechem, David B.; Kogan, Yefim L.; Schultz, David M.
2010-10-01
and continental stratocumulus to each other, the approach of large-eddy observation (LEO) was applied to a case of nocturnal continental stratocumulus observed over the Atmospheric Radiation Measurement Program (ARM) Climate Research Facility (ACRF) in the central...
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)
2011-06-23
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.
Computer simulations of the effects of the Sitka eddy on the migration of sockeye salmon returning
Hinch, Scott G.
Computer simulations of the effects of the Sitka eddy on the migration of sockeye salmon returning Ciencias Marinas, La Paz, BCX, Mexico 4 Forest Sciences Department, University of British Columbia and it has been suggested that the eddy could de¯ect migrating salmon to the south, thereby reducing
Adaptive Detached Eddy Simulation of a High Lift Wing with Active...
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
Vorticity contours colored by speed from a detached eddy simulation of flow around a high lift multi-element wing at maximum lift Vorticity contours colored by speed from a...
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
Direct Numerical Simulation and Large Eddy Simulation of Compressible Turbulence
Erlebacher, Gordon
of attention in the fluid dynamics community, owing perhaps to, the renewed interest in the de sign,b) Unfortunately, it is unlikely that the near future will bring about experiments detailed enough to confirm and in the definition of kinetic energy add a degree of complexity to the interpre tation of intermodal energy
Sandia Energy - Large Eddy Simulation (LES) of Engines
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
combustion has been established as a direct extension of the "International Workshop on Measurement and Computation of Turbulent Nonpremixed Flames" (i.e., the "TNF Workshop")....
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
Study of natural ventilation in buildings with large eddy simulation
Jiang, Yi, 1972-
2002-01-01
With the discovery of many economic, environmental, and health problems in sealed and mechanically ventilated buildings, the concept of natural ventilation has been revived. "Buildings that breathe" have become more and ...
Large Eddy Simulations of Jet Flow Interactions Within Rod Bundles
Salpeter, Nathaniel O.
2010-07-14
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...
Large Eddy Simulations of Combustor Liner Flows | Argonne Leadership...
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
barrels of oil per day, or about 6 percent of the world's total oil usage. Aviation gas turbine engines are also significant producers of CO2 and other harmful greenhouse gas...
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 Delicious RankADVANCED MANUFACTURING OFFICE INDUSTRIALU.S.Leadership on Clean Energy | Department ofThe new degree|
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 DeliciousMathematics And Statistics Â» USAJobs Search USAJobsAdvanced Engine CombustionLocator
Large Eddy Simulations of Combustor Liner Flows | Argonne Leadership
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AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Homesum_a_epg0_fpd_mmcf_m.xls" ,"Available from WebQuantity ofkandz-cm11 Outreach Home Room NewsInformationJesse Bergkamp Graduate studentScienceLaboratory program LabsDesign
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
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
ACCOLADES: A Scalable Workflow Framework for Large-Scale Simulation...
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
ACCOLADES: A Scalable Workflow Framework for Large-Scale Simulation and Analyses of Automotive Engines Title ACCOLADES: A Scalable Workflow Framework for Large-Scale Simulation and...
White, D
2009-04-30
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
2012-04-01
NREL researchers are the first to use a high-performance computing tool for a large-eddy simulation of an entire wind plant.
Sensitivity technologies for large scale simulation.
Collis, Samuel Scott; Bartlett, Roscoe Ainsworth; Smith, Thomas Michael; Heinkenschloss, Matthias; Wilcox, Lucas C.; Hill, Judith C.; Ghattas, Omar; Berggren, Martin Olof; Akcelik, Volkan; Ober, Curtis Curry; van Bloemen Waanders, Bart Gustaaf; Keiter, Eric Richard
2005-01-01
Sensitivity analysis is critically important to numerous analysis algorithms, including large scale optimization, uncertainty quantification,reduced order modeling, and error estimation. Our research focused on developing tools, algorithms and standard interfaces to facilitate the implementation of sensitivity type analysis into existing code and equally important, the work was focused on ways to increase the visibility of sensitivity analysis. We attempt to accomplish the first objective through the development of hybrid automatic differentiation tools, standard linear algebra interfaces for numerical algorithms, time domain decomposition algorithms and two level Newton methods. We attempt to accomplish the second goal by presenting the results of several case studies in which direct sensitivities and adjoint methods have been effectively applied, in addition to an investigation of h-p adaptivity using adjoint based a posteriori error estimation. A mathematical overview is provided of direct sensitivities and adjoint methods for both steady state and transient simulations. Two case studies are presented to demonstrate the utility of these methods. A direct sensitivity method is implemented to solve a source inversion problem for steady state internal flows subject to convection diffusion. Real time performance is achieved using novel decomposition into offline and online calculations. Adjoint methods are used to reconstruct initial conditions of a contamination event in an external flow. We demonstrate an adjoint based transient solution. In addition, we investigated time domain decomposition algorithms in an attempt to improve the efficiency of transient simulations. Because derivative calculations are at the root of sensitivity calculations, we have developed hybrid automatic differentiation methods and implemented this approach for shape optimization for gas dynamics using the Euler equations. The hybrid automatic differentiation method was applied to a first order approximation of the Euler equations and used as a preconditioner. In comparison to other methods, the AD preconditioner showed better convergence behavior. Our ultimate target is to perform shape optimization and hp adaptivity using adjoint formulations in the Premo compressible fluid flow simulator. A mathematical formulation for mixed-level simulation algorithms has been developed where different physics interact at potentially different spatial resolutions in a single domain. To minimize the implementation effort, explicit solution methods can be considered, however, implicit methods are preferred if computational efficiency is of high priority. We present the use of a partial elimination nonlinear solver technique to solve these mixed level problems and show how these formulation are closely coupled to intrusive optimization approaches and sensitivity analyses. Production codes are typically not designed for sensitivity analysis or large scale optimization. The implementation of our optimization libraries into multiple production simulation codes in which each code has their own linear algebra interface becomes an intractable problem. In an attempt to streamline this task, we have developed a standard interface between the numerical algorithm (such as optimization) and the underlying linear algebra. These interfaces (TSFCore and TSFCoreNonlin) have been adopted by the Trilinos framework and the goal is to promote the use of these interfaces especially with new developments. Finally, an adjoint based a posteriori error estimator has been developed for discontinuous Galerkin discretization of Poisson's equation. The goal is to investigate other ways to leverage the adjoint calculations and we show how the convergence of the forward problem can be improved by adapting the grid using adjoint-based error estimates. Error estimation is usually conducted with continuous adjoints but if discrete adjoints are available it may be possible to reuse the discrete version for error estimation. We investigate the advantages and disadvantages of continuous and discre
A Model for Turbulent Combustion Simulation of Large Scale Hydrogen...
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
A Model for Turbulent Combustion Simulation of Large Scale Hydrogen Explosions Event Sponsor: Argonne Leadership Computing Facility Seminar Start Date: Oct 6 2015 - 10:00am...
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 and Analysis of Tip-Clearance Flows in Turbomachinery Applications
Mittal, Rajat
on understanding the underlying mechanisms for low- pressure fluctuations and cavitation downstream of the tip In hydraulic turbomachines such as submarine propulsors and liquid fuel pumps, the existence of radial that cavitation is associated with low-pressure fluctuations downstream of the tip-gap, the underlying mechanisms
Kewlani, Gaurav
2014-01-01
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 ...
Large-Eddy Simulation of the Bachalo-Johnson Flow, with Shock...
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
(SBLIs) are of particular interest to aerospace companies and the gas-turbine industry, and some proposals for carbon capture and sequestration also involve supersonic...
Helton, Donald McLean
2002-01-01
to the channel centerline. Furthermore, substantial interaction between the obstacle and the wall was noted, both near the obstacle and further downstream. The boundary layer downstream of the obstacle was dramatically affected by the obstacle's presence...
Modeling passive scalar dispersion in the atmospheric boundary layer with WRF large-eddy simulation
Nottrott, Anders; Kleissl, Jan; Keeling, Ralph
2014-01-01
self-similarity only in the crosswind direction. Thoseas the vertical and crosswind dimensions of the plumeObukhov length streamwise, crosswind horizontal and vertical
DIRECT AND LARGE EDDY SIMULATIONS OF A BOTTOM EKMAN LAYER UNDER AN EXTERNAL STRATIFICATION
Taylor, John R.
be approximated as an adiabatic boundary with the excep- tion of isolated geothermal hotspots. However stratification and vertical shear, both with and without a surface heat flux. They used their results
Large-eddy Simulation of the Nighttime Stable Atmospheric Boundary Layer
Zhou, Bowen
2012-01-01
and wind turbine micro-siting in complex terrain. ” Journal of Wind Engineering and Industrial Aerodynamics
Large Eddy Simulation Analysis of Flow Field Inside a High-g Combustor
Raman, Venkat
Base, Ohio 45433 Inter-turbine burners are useful devices for increasing engine power. To enable inter. Introduction Inter-turbine burners (ITBs) are emerging as a useful concept for increasing aircraft engine power
Flame Stability Analysis in an Ultra Compact Combustor Using Large-Eddy Simulation
Raman, Venkat
. Introduction The placement of inter-turbine burners (ITB) between the high and low pressure turbine stages as a conven- tional combustor path. In order to reduce the penalty due to increased weight of these burners-turbine burners using conventional combustion technology for aerospace applications would face similar size
Assessment of combustion noise in a premixed swirled combustor via Large-Eddy Simulation
Nicoud, Franck
in the study of aerodynamical generated noise of numerous practical cases that range from air jets, high [1,2]. On the contrary, thermoacoustics is less understood than aeroacoustics. This is caused with thermoacoustics since the transport equation of each species must be considered in order to solve the problem
Extracting the Acoustic pressure field from Large Eddy Simulation of confined reactive flows
Nicoud, Franck
. In aeroacoustics, LES plays an important role in the study of aerodynamical generated noise of numerous practical with thermoacoustics since the transport equation of each species must be considered in order to solve the problem
Aalborg Universitet Large Eddy Simulation of Sydney Swirl Non-Reaction Jets
Berning, Torsten
#12;V European Conference on Computational Fluid Dynamics ECCOMAS CFD 2010 J. C. F. Pereira and A. In combustion systems, the swirl devices are usually used to stabilize the flame and shorten its length
Ayache, Simon
2012-09-03
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 Pulverized Coal Jet Flame -Effect of Oxygen Concentration on NOx formation
Muto, Masaya; Watanabe, Hiroaki; Kurose, Ryoichi; Komori, Satoru; Balusamy, Saravanan; Hochgreb, Simone
2014-11-13
. The results are much more abundant than those of other fossil fuels and widely distributed all over the world. However, the emission inten- sities of carbon dioxide (CO2), nitrogen oxide (NOx) and sulfur oxide (SOx) by using coal are generally larger 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 con- trol such emissions and to reduce the environmental impact. ct of CO2, carbon a key technology, l...
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
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
Large-eddy Simulation of the Nighttime Stable Atmospheric Boundary Layer
Zhou, Bowen
2012-01-01
of US winds and wind power at 80 m derived fromMaxima and Problem of Wind Power Assessment. ” Environmentalsiting and operational wind power forecasting. For example,
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 the Nighttime Stable Atmospheric Boundary Layer
Zhou, Bowen
2012-01-01
At nighttime, wind turbines extract more energy from thewind energy applications, MO similarity must be used with caution under strong stability conditions for predicting wind at turbineWind Energy 2 Abstract The near-surface structure of atmospheric turbulence affects the design and operation of wind turbines
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
Large-eddy Simulation of the Nighttime Stable Atmospheric Boundary Layer
Zhou, Bowen
2012-01-01
Turbulence/Rotor Interactions. ” Wind Energy 3 (3): 121–134.to complex terrain. ” Wind Energy 14 (2) (March): 225–237.Patterns at Midwest Wind Energy Facilities. ” In Proceedings
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
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
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 the combustion chamber, where fast mixing with fuel is necessary to ensure stable combustion and engine operation. Dual- mode scramjets provide a practical solution to hypersonic flight by operating at both low
Large Eddy Simulation of Stable Boundary Layer Turbulent Processes in Complex Terrain
Eric D. Skyllingstad
2005-01-26
Research was performed using a turbulence boundary layer model to study the behavior of cold, dense flows in regions of complex terrain. Results show that flows develop a balance between turbulent entrainment of warm ambient air and dense, cold air created by surface cooling. Flow depth and strength is a function of downslope distance, slope angle and angle changes, and the ambient air temperature.
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 Delicious RankADVANCED MANUFACTURING OFFICE INDUSTRIALU.S.Leadership on Clean Energy | Department ofThe new
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 Delicious RankADVANCED MANUFACTURING OFFICE INDUSTRIALU.S.Leadership on Clean Energy | Department ofThe newCombustion
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 Delicious RankADVANCED MANUFACTURING OFFICE INDUSTRIALU.S.Leadership on Clean Energy | Department ofThe
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Homesum_a_epg0_fpd_mmcf_m.xls" ,"Available from WebQuantityBonneville Power Administration would likeUniverseIMPACTThousand CubicResourcelogo and mastheadLakeLanguage of a fly
Barnes, Elizabeth A.
Testing a theory for the effect of latitude on the persistence of eddy driven jets using CMIP3south shifts in the position of the jet is investigated in 37 CMIP3 integrations over four forcing scenarios. The persistence of the Southern Annular Mode (SAM) decreases when the mean jet is located closer to the pole
Direct Numerical Simulation of the Flow in a Pebble Bed
Ward, Paul
2014-06-24
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.
2004-06-30
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
DesJardin, Paul E.
diameters from the fuel source are of greatest interest since the bulk of the combustion takes place a fire requires accurate modeling of turbulent, combustion, and thermal radiation processes. A full description of all these processes has proven to be an enormous challenge for CFD modeling. The approach
The use of large plot rainfall simulation to investigate
Sorenson, Joshua Russell
2006-04-12
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 ...
Simulation of Convection and Macrosegregation in a Large Steel Ingot
Beckermann, Christoph
convection and macrosegregation in casting of a large steel ingot are numerically simulated. The simulation of a shrinkage cavity at the top, is taken into account. The numerical results show the evolution macrosegregation observed in the lower part of the ingot. It is also shown that the inclusion of the shrinkage
Hoelzl, M; Merkel, P; Atanasiu, C; Lackner, K; Nardon, E; Aleynikova, K; Liu, F; Strumberger, E; McAdams, R; Chapman, I; Fil, A
2014-01-01
The dynamics of large scale plasma instabilities can strongly be influenced by the mutual interaction with currents flowing in conducting vessel structures. Especially eddy currents caused by time-varying magnetic perturbations and halo currents flowing directly from the plasma into the walls are important. The relevance of a resistive wall model is directly evident for Resistive Wall Modes (RWMs) or Vertical Displacement Events (VDEs). However, also the linear and non-linear properties of most other large-scale instabilities may be influenced significantly by the interaction with currents in conducting structures near the plasma. The understanding of halo currents arising during disruptions and VDEs, which are a serious concern for ITER as they may lead to strong asymmetric forces on vessel structures, could also benefit strongly from these non-linear modeling capabilities. Modeling the plasma dynamics and its interaction with wall currents requires solving the magneto-hydrodynamic (MHD) equations in realist...
Prediction of Small-Scale Cavitation in a High Speed Flow Over an Open Cavity Using Large Eddy
Apte, Sourabh V.
Simulation Ehsan Shams Sourabh V. Apte Computational Flow Physics Laboratory School of Mechanical Industrial on structural vibra- tions, noise production, erosion of propulsor blades, among others [2]. To devise mechanisms of cavitation inception emphasizing that cavita- tion inception and turbulence are inseparable
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.
2011-06-28
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 ...
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Homesum_a_epg0_fpd_mmcf_m.xls" ,"Available from WebQuantityBonneville Power Administration would like submit theCovalent BondingMeeting |DesignCommunitiesYu &Diagnosis of Lower
PANS method of turbulence: simulation of high and low Reynolds number flows past a circular cylinder
Lakshmipathy, Sunil
2006-04-12
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...
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
Simulating the Large-Scale Structure of HI Intensity Maps
Seehars, Sebastian; Witzemann, Amadeus; Refregier, Alexandre; Amara, Adam; Akeret, Joel
2015-01-01
Intensity mapping of neutral hydrogen (HI) is a promising observational probe of cosmology and large-scale structure. We present wide field simulations of HI intensity maps based on N-body simulations, the halo model, and a phenomenological prescription for assigning HI mass to halos. The simulations span a redshift range of 0.35 HI. We apply and compare several estimators for the angular power spectrum and its covariance. We verify that they agree with analytic predictions on large scales and study the validity of approximations based on Gaussian random fields, particularly in the context of the covariance. We discuss how our results and the simulated maps can be useful for planning and interpreting future HI intensity mapping surveys.
Not Available
2011-02-01
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.
Tidal Residual Eddies and their Effect on Water Exchange in Puget Sound
Yang, Zhaoqing; Wang, Taiping
2013-08-30
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
2011-01-01
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
2011-02-07
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...
Mechem, David B.; Kogan, Yefim L.
2003-10-01
variability is analogous to the drizzle-induced cloud breakup produced in large eddy simulation studies. The dynamics of the pure stratocumulus cloud are dictated by the model's subgrid parameterization, while the more convective regime exhibits appreciable...
In-situ sampling of a large-scale particle simulation for interactive...
Office of Scientific and Technical Information (OSTI)
random sampling of data from large scale particle simulations, such as the Roadrunner Universe MCsup 3 cosmological simulation, to be used for interactive post-analysis and...
Large scale structure simulations of inhomogeneous LTB void models
David Alonso; Juan Garcia-Bellido; Troels Haugboelle; Julian Vicente
2011-01-11
We perform numerical simulations of large scale structure evolution in an inhomogeneous Lemaitre-Tolman-Bondi (LTB) model of the Universe. We follow the gravitational collapse of a large underdense region (a void) in an otherwise flat matter-dominated Einstein-deSitter model. We observe how the (background) density contrast at the centre of the void grows to be of order one, and show that the density and velocity profiles follow the exact non-linear LTB solution to the full Einstein equations for all but the most extreme voids. This result seems to contradict previous claims that fully relativistic codes are needed to properly handle the non-linear evolution of large scale structures, and that local Newtonian dynamics with an explicit expansion term is not adequate. We also find that the (local) matter density contrast grows with the scale factor in a way analogous to that of an open universe with a value of the matter density OmegaM(r) corresponding to the appropriate location within the void.
Statistical and Directable Methods for Large-Scale Rigid Body Simulation
Hsu, Shu-Wei
2013-05-07
This dissertation describes several techniques to improve performance and controllability of large-scale rigid body simulations. We first describe a statistical simulation method that replaces certain stages of rigid body simulation with a...
Arc plasma simulation of the KAERI large ion source
In, S. R.; Jeong, S. H.; Kim, T. S.
2008-02-15
The KAERI large ion source, developed for the KSTAR NBI system, recently produced ion beams of 100 keV, 50 A levels in the first half campaign of 2007. These results seem to be the best performance of the present ion source at a maximum available input power of 145 kW. A slight improvement in the ion source is certainly necessary to attain the final goal of an 8 MW ion beam. Firstly, the experimental results were analyzed to differentiate the cause and effect for the insufficient beam currents. Secondly, a zero dimensional simulation was carried out on the ion source plasma to identify which factors control the arc plasma and to find out what improvements can be expected.
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
2012-06-12
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
Zhang, Huangwei; Garmory, Andrew; Cavaliere, Davide E.; Mastorakos, Epaminondas
2014-06-25
University of Cambridge, Cambridge CB2 1PZ, United Kingdom Tel: +44 1223 332690, Fax: +44 1223 332662 Email: hz283@cam.ac.uk Colloquium topic: 5. Turbulent flames Alternative Colloquium topic: 11. IC engine and gas turbine combustion Paper length... -off * Corresponding author. E-mail: hz283@cam.ac.uk. Tel: +44 1223 332690. 2 1. Introduction Swirl flows are virtually ubiquitous in gas turbines [1-3]. However, the strong turbulent fluctuations due to the intense shear can lead to finite rate chemistry effects...
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
2011-01-01
such as the urban heat island and increase in urban energyloads and the urban heat island-the effects of albedo,modeling of urban heat islands. Final report prepared by
Sun, Long
2011-01-01
loads and the urban heat island-the effects of albedo,modeling of urban heat islands. Final report prepared byeffects such as the urban heat island and increase in urban
Oberai, Assad A [Rensselaer Polytechnic Instistute
2013-07-16
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.
Nottrott, Anders Andelman
2014-01-01
of SGS model and grid resolution on horizontal crosswind37 Self-similarity of horizontal crosswind profiles of mean39 Crosswind horizontal profiles of concentration variance
Sun, Long
2011-01-01
pollution. In this research numerical methods are used to investigate some basic turbulent and thermal
Sun, Long
2011-01-01
loads and the urban heat island-the effects of albedo,modeling of urban heat islands. Final report prepared byespecially the urban heat island (UHI) and urban air
Sun, Long
2011-01-01
losses of a flat-plate collector, Solar Energy 35, 15–19.from outer cover of solar collectors, Renew. Energ. 10 (4)
Sun, Long
2011-01-01
Hernandez, Matthew Lave and Neda Yaghoobian. Especiallyto me in my dissertation review, Neda Yaghoobian and Anthony
Sun, Long
2011-01-01
downwind of the hill shows small wind speeds (Fig. 4.4a).downwind of the hill shows small wind speeds (Fig.4.4a). For
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.
Nuclear EMP simulation for large-scale urban environments. FDTD for electrically large problems.
Smith, William S.; Bull, Jeffrey S.; Wilcox, Trevor; Bos, Randall J.; Shao, Xuan-Min; Goorley, John T.; Costigan, Keeley R.
2012-08-13
In case of a terrorist nuclear attack in a metropolitan area, EMP measurement could provide: (1) a prompt confirmation of the nature of the explosion (chemical or nuclear) for emergency response; and (2) and characterization parameters of the device (reaction history, yield) for technical forensics. However, urban environment could affect the fidelity of the prompt EMP measurement (as well as all other types of prompt measurement): (1) Nuclear EMP wavefront would no longer be coherent, due to incoherent production, attenuation, and propagation of gamma and electrons; and (2) EMP propagation from source region outward would undergo complicated transmission, reflection, and diffraction processes. EMP simulation for electrically-large urban environment: (1) Coupled MCNP/FDTD (Finite-difference time domain Maxwell solver) approach; and (2) FDTD tends to be limited to problems that are not 'too' large compared to the wavelengths of interest because of numerical dispersion and anisotropy. We use a higher-order low-dispersion, isotropic FDTD algorithm for EMP propagation.
Preliminary Investigations of Eddy Current Effects on a Spinning Disk
Piggott, W T; Walston, S; Mayhall, D
2006-09-08
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.
1996-01-01
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...
Orientation of eddy fluxes in geostrophic turbulence
Nadiga, Balasubramanya T. "Balu"
of potential vorticity (PV) in geostrophic turbulence. We take two different points of view, a classical of the eddy flux of PV with the appropriate mean gradient or the large-scale gradient of PV is required-temporal characteristics of the flow. One way to improve on this is to adopt unsteady RA. In this case, averages
Effects of Drake Passage on a strongly eddying global ocean
Viebahn, Jan P; Bars, Dewi Le; Dijkstra, Henk A
2015-01-01
The climate impact of ocean gateway openings during the Eocene-Oligocene transition is still under debate. Previous model studies employed grid resolutions at which the impact of mesoscale eddies has to be parameterized. We present results of a state-of-the-art eddy-resolving global ocean model with a closed Drake Passage, and compare with results of the same model at non-eddying resolution. An analysis of the pathways of heat by decomposing the meridional heat transport into eddy, horizontal, and overturning circulation components indicates that the model behavior on the large scale is qualitatively similar at both resolutions. Closing Drake Passage induces (i) sea surface warming around Antarctica due to changes in the horizontal circulation of the Southern Ocean, (ii) the collapse of the overturning circulation related to North Atlantic Deep Water formation leading to surface cooling in the North Atlantic, (iii) significant equatorward eddy heat transport near Antarctica. However, quantitative details sign...
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
Large-Scale Molecular Dynamics Simulations for Highly Parallel Infrastructures
Pazúriková, Jana
2014-01-01
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
Large-Scale Simulation of Neural Networks with Biophysically Accurate Models on Graphics Processors
Wang, Mingchao
2012-07-16
Efficient simulation of large-scale mammalian brain models provides a crucial computational means for understanding complex brain functions and neuronal dynamics. However, such tasks are hindered by significant computational complexities...
Modeling a Large Data Acquisition Network in a Simulation Framework
Colombo, Tommaso; The ATLAS collaboration
2015-01-01
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...
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
Modeling of Diesel Combustion, Soot and NO Emissions Based on a Modified Eddy Dissipation Concept
Im, Hong G.
1 Modeling of Diesel Combustion, Soot and NO Emissions Based on a Modified Eddy Dissipation Concept and soot emissions modeling, computational diesel engine simulations, eddy dissipation concept #12 ignition, combustion, NOx and soot emissions over a wide range of operating conditions in a diesel engine
Effects of Sea-Salt Aerosols on Precipitation in Simulations of Shallow Cumulus
Kogan, Yefim L.; Mechem, David B.; Choi, Kityan
2012-02-01
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 the Rain in Cumulus over...
LES/probability density function approach for the simulation of an ethanol spray flame
Raman, Venkat
LES/probability density function approach for the simulation of an ethanol spray flame Colin Heye a an experimental pilot-stabilized ethanol spray flame. In this particular flame, droplet evaporation occurs away: Large-eddy simulation; Probability density function; Flamelet/progress variable approach; Ethanol
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
2006-11-28
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.
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 of oceanic gyres is addressed. While previous studies have shown that eddies generated from weakly sheared
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 frequency (HF) winds on the inertial motions and the consequences on the large-scale oceanic circulation the impact of HF winds on the inertial motions. However the eddies efficiently and permanently concentrate
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
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
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
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
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
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
Large scale simulations of lattice gauge theory: key NSF project of China and recent developments
Xiang-Qian Luo
2003-10-08
In a recent funded Key Project of National Science Foundation of China, we have planned to do large scale simulations of lattice Quantum Chromodynamics, using the parallel supercomputing facilities in mainland China. Here I briefly review our plan and progress in recent years.
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
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)
2011-06-23
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.
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.
2013-01-02
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.
Seabird associations with mesoscale eddies: the subtropical Indian Ocean
Hyrenbach, KD; Veit, RR; Weimerskirch, H; Jr, HGL
2006-01-01
Seabird associations with mesoscale eddies: the subtropicalsur- hydrographic fronts and mesoscale eddies (Haney & veyedclimatologies. J Clim mesoscale variability across ocean
Parametric instabilities of large-amplitude parallel propagating Alfven waves: 2-D PIC simulation
Yasuhiro Nariyuki; Shuichi Matsukiyo; Tohru Hada
2008-04-25
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.
Large scale simulations of the jet-IGM interaction Martin G. H. Krause
Krause, Martin
in that phase. Here, I present new, bipolar, simulations of very light jets in 2.5D and 3D, reaching (Carvalho and O'Dea, 2002a; Car- valho and O'Dea, 2002b; Saxton et al., 2002; Krause, 2003; Zanni et al ambient gas mass distribution and E(t) is the energy injection law. Here, I show 3D and 2.5D large scale
Eddy current scanning at Fermilab
Boffo, C.; Bauer, P.; Foley, M.; /Fermilab; Brinkmann, A.; /DESY; Ozelis, J.; /Jefferson Lab
2005-07-01
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.
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.; Lloyd, Levi; Minnich, Ronald G.; Vanderveen, Keith; Van Randwyk, Jamie A; Rudish, Don W.
2008-10-01
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
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)
1994-01-01
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.
Calculation of Eddy Currents In the CTH Vacuum Vessel and Coil Frame
A. Zolfaghari, A. Brooks, A. Michaels, J. Hanson, and G. Hartwell
2012-09-25
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. __________________________________________________
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.
2006-06-23
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.
Shay I. Heizler; David A. Kessler
2015-05-18
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.
2004-01-01
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.
1997-08-01
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)
2014-01-15
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
2015-01-01
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...
Shimojo, Fuyuki; Hattori, Shinnosuke [Collaboratory for Advanced Computing and Simulations, Department of Physics and Astronomy, Department of Computer Science, and Department of Chemical Engineering and Materials Science, University of Southern California, Los Angeles, California 90089-0242 (United States) [Collaboratory for Advanced Computing and Simulations, Department of Physics and Astronomy, Department of Computer Science, and Department of Chemical Engineering and Materials Science, University of Southern California, Los Angeles, California 90089-0242 (United States); Department of Physics, Kumamoto University, Kumamoto 860-8555 (Japan); Kalia, Rajiv K.; Mou, Weiwei; Nakano, Aiichiro; Nomura, Ken-ichi; Rajak, Pankaj; Vashishta, Priya [Collaboratory for Advanced Computing and Simulations, Department of Physics and Astronomy, Department of Computer Science, and Department of Chemical Engineering and Materials Science, University of Southern California, Los Angeles, California 90089-0242 (United States)] [Collaboratory for Advanced Computing and Simulations, Department of Physics and Astronomy, Department of Computer Science, and Department of Chemical Engineering and Materials Science, University of Southern California, Los Angeles, California 90089-0242 (United States); Kunaseth, Manaschai [Collaboratory for Advanced Computing and Simulations, Department of Physics and Astronomy, Department of Computer Science, and Department of Chemical Engineering and Materials Science, University of Southern California, Los Angeles, California 90089-0242 (United States) [Collaboratory for Advanced Computing and Simulations, Department of Physics and Astronomy, Department of Computer Science, and Department of Chemical Engineering and Materials Science, University of Southern California, Los Angeles, California 90089-0242 (United States); National Nanotechnology Center, Pathumthani 12120 (Thailand); Ohmura, Satoshi [Collaboratory for Advanced Computing and Simulations, Department of Physics and Astronomy, Department of Computer Science, and Department of Chemical Engineering and Materials Science, University of Southern California, Los Angeles, California 90089-0242 (United States) [Collaboratory for Advanced Computing and Simulations, Department of Physics and Astronomy, Department of Computer Science, and Department of Chemical Engineering and Materials Science, University of Southern California, Los Angeles, California 90089-0242 (United States); Department of Physics, Kumamoto University, Kumamoto 860-8555 (Japan); Department of Physics, Kyoto University, Kyoto 606-8502 (Japan); Shimamura, Kohei [Collaboratory for Advanced Computing and Simulations, Department of Physics and Astronomy, Department of Computer Science, and Department of Chemical Engineering and Materials Science, University of Southern California, Los Angeles, California 90089-0242 (United States) [Collaboratory for Advanced Computing and Simulations, Department of Physics and Astronomy, Department of Computer Science, and Department of Chemical Engineering and Materials Science, University of Southern California, Los Angeles, California 90089-0242 (United States); Department of Physics, Kumamoto University, Kumamoto 860-8555 (Japan); Department of Applied Quantum Physics and Nuclear Engineering, Kyushu University, Fukuoka 819-0395 (Japan)
2014-05-14
We introduce an extension of the divide-and-conquer (DC) algorithmic paradigm called divide-conquer-recombine (DCR) to perform large quantum molecular dynamics (QMD) simulations on massively parallel supercomputers, in which interatomic forces are computed quantum mechanically in the framework of density functional theory (DFT). In DCR, the DC phase constructs globally informed, overlapping local-domain solutions, which in the recombine phase are synthesized into a global solution encompassing large spatiotemporal scales. For the DC phase, we design a lean divide-and-conquer (LDC) DFT algorithm, which significantly reduces the prefactor of the O(N) computational cost for N electrons by applying a density-adaptive boundary condition at the peripheries of the DC domains. Our globally scalable and locally efficient solver is based on a hybrid real-reciprocal space approach that combines: (1) a highly scalable real-space multigrid to represent the global charge density; and (2) a numerically efficient plane-wave basis for local electronic wave functions and charge density within each domain. Hybrid space-band decomposition is used to implement the LDC-DFT algorithm on parallel computers. A benchmark test on an IBM Blue Gene/Q computer exhibits an isogranular parallel efficiency of 0.984 on 786?432 cores for a 50.3 × 10{sup 6}-atom SiC system. As a test of production runs, LDC-DFT-based QMD simulation involving 16?661 atoms is performed on the Blue Gene/Q to study on-demand production of hydrogen gas from water using LiAl alloy particles. As an example of the recombine phase, LDC-DFT electronic structures are used as a basis set to describe global photoexcitation dynamics with nonadiabatic QMD (NAQMD) and kinetic Monte Carlo (KMC) methods. The NAQMD simulations are based on the linear response time-dependent density functional theory to describe electronic excited states and a surface-hopping approach to describe transitions between the excited states. A series of techniques are employed for efficiently calculating the long-range exact exchange correction and excited-state forces. The NAQMD trajectories are analyzed to extract the rates of various excitonic processes, which are then used in KMC simulation to study the dynamics of the global exciton flow network. This has allowed the study of large-scale photoexcitation dynamics in 6400-atom amorphous molecular solid, reaching the experimental time scales.
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
2009-02-17
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).
A method of orbital analysis for large-scale first-principles simulations
Ohwaki, Tsukuru; Otani, Minoru; Ozaki, Taisuke
2014-06-28
An efficient method of calculating the natural bond orbitals (NBOs) based on a truncation of the entire density matrix of a whole system is presented for large-scale density functional theory calculations. The method recovers an orbital picture for O(N) electronic structure methods which directly evaluate the density matrix without using Kohn-Sham orbitals, thus enabling quantitative analysis of chemical reactions in large-scale systems in the language of localized Lewis-type chemical bonds. With the density matrix calculated by either an exact diagonalization or O(N) method, the computational cost is O(1) for the calculation of NBOs associated with a local region where a chemical reaction takes place. As an illustration of the method, we demonstrate how an electronic structure in a local region of interest can be analyzed by NBOs in a large-scale first-principles molecular dynamics simulation for a liquid electrolyte bulk model (propylene carbonate + LiBF{sub 4})
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
Kemner, Ken
Eddy-Current-Induced Multipole Field Calculations September 29, 2003 1 Eddy-Current of magnets in booster accelerators induce substantial eddy currents in the vacuum chambers. The eddy currents are generated in the elliptical vacuum chamber from the induced eddy currents. In this note, formulas
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
2012-01-15
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
2013-01-01
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.
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
Magnetic diagnostics for equilibrium reconstructions with eddy...
Office of Scientific and Technical Information (OSTI)
Magnetic diagnostics for equilibrium reconstructions with eddy currents on the lithium tokamak experimenta) Citation Details In-Document Search Title: Magnetic diagnostics for...
EDDY CURRENT MODEL FOR NONDESTRUCTIVE EVALUATION ...
2015-04-05
remote-field eddy current problems for the nondestructive testing of metal tube using finite element ..... For non-destructive testing, we usually have. 0 < d ? min.
Eddy formation and propagation in the eastern tropical Pacific
Jhingran, Vikas Gopal
1997-01-01
Observations of eddies in the eastern tropical Pacific from TOPEX altimetry data show that there are seasonal and interannual variations in eddy activity. Comparisons between time of eddy formation and corresponding wind ...
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: Alternative Fuels Data Center Homesum_a_epg0_fpd_mmcf_m.xls" ,"Available from WebQuantityBonneville Power Administration would likeUniverseIMPACTThousand CubicResourcelogo and mastheadLakeLanguage of a fly provesLarge
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
2012-01-01
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...
Transient eddy current flow metering
Forbriger, Jan
2015-01-01
Measuring local velocities or entire flow rates in liquid metals or semiconductor melts is a notorious problem in many industrial applications, including metal casting and silicon crystal growth. We present a new variant of an old technique which relies on the continuous tracking of a flow-advected transient eddy current that is induced by a pulsed external magnetic field. This calibration-free method is validated by applying it to the velocity of a spinning disk made of aluminum. First tests at a rig with a flow of liquid GaInSn are also presented.
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: Alternative Fuels Data Center Homesum_a_epg0_fpd_mmcf_m.xls" ,"Available from WebQuantityBonneville Power Administration would like submitKansas Nuclear Profile 2010Mesoscopy andSavingYearOutreach Program2 Eddy
Bu, De-Fu; Gan, Zhao-Ming; Yang, Xiao-hong
2015-01-01
In previous works, it has been shown that strong winds exist in hot accretion flows around black holes. Those works focus only on the region close to the black hole thus it is unknown whether or where the wind production stops at large radii. In this paper, we investigate this problem based on hydrodynamical numerical simulations. For this aim, we have taken into account the gravity of both the central black hole and the nuclear star clusters. When calculating the latter, we assume that the velocity dispersion of stars is a constant and the gravitational potential of the nuclear star cluster $\\propto \\sigma^2 \\ln (r)$, where $\\sigma$ is the velocity dispersion of stars and $r$ is the distance from the center of the galaxy. Different from previous works, we focus on the region where the gravitational potential is dominated by the star cluster. We find that, same as the accretion flow at small radii, the mass inflow rate decreases inward and the flow is convectively unstable. However, trajectory analysis has sh...
A Report on Simulation-Driven Reliability and Failure Analysis of Large-Scale Storage Systems
Wan, Lipeng; Wang, Feiyi; Oral, H. Sarp; Vazhkudai, Sudharshan S.; Cao, Qing
2014-11-01
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
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)
2005-04-09
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
2012-02-02
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.
Oak Ridge National Laboratory
Envelope 1. Large Scale Climate Simulator (Building 3144) The LSCS tests roof and/or attic accommodates specimens of up to 606020 cm 24248 in.). 5. Roof Thermal Research Apparatus (Apparatus 3138) #12;RTRA measures effects of long-term natural weather exposure on small, low-slope roof specimens
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
Deelman, Ewa
Laboratory 2 Computation Institute, Argonne National Laboratory & University of Chicago 3 Center for Climatic hindered the efforts of the climate community to understand climate variability and climate change fromAutomating Climate Science: Large Ensemble Simulations on the TeraGrid with the GriPhyN Virtual
Rotating concave eddy current probe
Roach, Dennis P. (Albuquerque, NM); Walkington, Phil (Albuquerque, NM); Rackow, Kirk A. (Albuquerque, NM); Hohman, Ed (Albuquerque, NM)
2008-04-01
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.
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)
2003-01-01
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.
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
2005-03-24
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 MODEL FOR NONDESTRUCTIVE EVALUATION ...
2015-04-05
This implies the conservation of electrons in ?c, namely, the eddy current density. J = i??A satisfies div J = 0 in ?c and. J · n = 0 on ??c . (3.2). Now we consider ...
Eddy-current-induced multipole field calculations.
Sereno, N. S.; Kim, S. H.
2003-10-15
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.
Modeling and Simulation of Advanced Nano-Scale Very Large Scale Integration Circuits
Zhou, Ying
2010-07-14
) 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
Chen, Qiang
2005-08-29
turbine and heat recovery steam generator and identified significant potential savings. Finally, the author also used a steam turbine as an example to present a multi-regression method on constructing simulation models by using basic statistics...
Chen, Q.
2004-01-01
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. ...
John A. Sidles; Joseph L. Garbini; Lee E. Harrell; Alfred O. Hero; Jonathan P. Jacky; Joseph R. Malcomb; Anthony G. Norman; Austin M. Williamson
2008-05-13
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)
2011-06-23
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.
Simulation Support for Optimizing the Design and Operation of a Large Open-Space Office Building
Lain, M.; Hensen, J.; Zemlicka, J.
2008-01-01
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...
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
1997-08-07
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.
Paris-Sud XI, Université de
IEEE TRANSACTIONS ON MAGNETICS, VOL. 31, NO. 3, MAY 1995 2026 Geometrical optimizationof sensors for eddy currents Non Destructive Testing and Evaluation FrkddricTHOLLON-Nod BURAIS CEGELY- URA CNRS 829 and NDE sensors is possible by solving Maxwell's relations with FEM or BIM. But the large numberof
Meridional Eddy Heat Flux Density: Direct observations of q in the ocean are
Rhode Island, University of
Meridional Eddy Heat Flux Density: ·Direct observations of q in the ocean are sparse and exhibit large spatio-temporal variability. ·Differential heating of the globe causes a net transport of heat (Qtot) poleward by the ocean and atmosphere. ·Models predict at 36oN in the Pacific that total heat
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
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
Sandia Energy - Large-Scale Computational Fluid Dynamics
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Homesum_a_epg0_fpd_mmcf_m.xls" ,"Available from WebQuantity ofkandz-cm11 Outreach Home RoomPreservation of Fe(II)Geothermal Energy &Water Power ProgramLarge Eddy Simulation
Interpreting observed northern hemisphere snow trends with large ensembles of climate simulations
seasonal snow cover are analyzed in large ensembles of climate integrations of the National Center climatology and variability of snow cover extent as char- acterized by the NOAA snow chart climate data record change Á Snow Á Climate models Á Pacific decadal oscillation 1 Introduction Seasonal snow cover is a key
Casimir interaction from magnetically coupled eddy currents
Francesco Intravaia; Carsten Henkel
2009-09-06
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)
2009-09-25
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
2011-01-31
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.
Benedetto, Elena; Schulte, Daniel; Rumolo, Giovanni
2005-01-01
The electron cloud may cause transverse single-bunch instabilities of proton beams such as those in the Large Hadron Collider (LHC) and the CERN Super Proton Synchrotron (SPS). We simulate these instabilities and the consequent emittance growth with the code HEADTAIL, which models the turn-by-turn interaction between the cloud and the beam. Recently some new features were added to the code, in particular, electric conducting boundary conditions at the chamber wall, transverse feedback, and variable beta functions. The sensitivity to several numerical parameters has been studied by varying the number of interaction points between the bunch and the cloud, the phase advance between them, and the number of macroparticles used to represent the protons and the electrons. We present simulation results for both LHC at injection and SPS with LHC-type beam, for different electron-cloud density levels, chromaticities, and bunch intensities. Two regimes with qualitatively different emittance growth are observed: above th...
Chen, Ru
The assumption that local baroclinic instability dominates eddy–mean flow interactions is tested on a global scale using a dynamically consistent eddy-permitting state estimate. Interactions are divided into local and ...
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
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
Eddie Holt, Yeats, Journalism and the Revival UCDscholarcast 1
Eddie Holt, Yeats, Journalism and the Revival UCDscholarcast 1 UCDscholarcast Series 1: (Spring.J. Mathews © UCDscholarcast #12;Eddie Holt, Yeats, Journalism and the Revival UCDscholarcast 2 Eddie Holt Yeats, Journalism and the Revival I suspect most people find it hard to think of WB Yeats
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
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
Hagos, Samson M.; Leung, Lai-Yung R.
2012-11-01
Cloud resolving model simulations and vector analysis are used to develop a quantitative method of assessing regional variations in the relationships between various large-scale environmental variables and the transition to deep convection. Results of the CRM simulations from three tropical regions are used to cluster environmental conditions under which transition to deep convection does and does not take place. Projections of the large-scale environmental variables on the difference between these two clusters are used to quantify the roles of these variables in the transition to deep convection. While the transition to deep convection is most sensitive to moisture and vertical velocity perturbations, the details of the profiles of the anomalies vary from region to region. In comparison, the transition to deep convection is found to be much less sensitive to temperature anomalies over all three regions. The vector formulation presented in this study represents a simple general framework for quantifying various aspects of how the transition to deep convection is sensitive to environmental conditions.
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: Alternative Fuels Data Center Homesum_a_epg0_fpd_mmcf_m.xls" ,"Available from WebQuantity of NaturalDukeWakefieldSulfateSciTech ConnectSpeedingConnect Pulse energy(Conference) | SciTechQuirkssimulations of
Demand Shifting With Thermal Mass in Large Commercial Buildings:Field Tests, Simulation and Audits
Xu, Peng; Haves, Philip; Piette, Mary Ann; Zagreus, Leah
2005-09-01
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.
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)
2012-12-15
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)
2011-06-23
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.
Sotnikov, V.; Kim, T.; Lundberg, J.; Paraschiv, I.; Mehlhorn, T. A.
2014-05-15
The presence of plasma turbulence can strongly influence propagation properties of electromagnetic signals used for surveillance and communication. In particular, we are interested in the generation of low frequency plasma density irregularities in the form of coherent vortex structures. Interchange or flute type density irregularities in magnetized plasma are associated with Rayleigh-Taylor type instability. These types of density irregularities play an important role in refraction and scattering of high frequency electromagnetic signals propagating in the earth ionosphere, in high energy density physics, and in many other applications. We will discuss scattering of high frequency electromagnetic waves on low frequency density irregularities due to the presence of vortex density structures associated with interchange instability. We will also present particle-in-cell simulation results of electromagnetic scattering on vortex type density structures using the large scale plasma code LSP and compare them with analytical results.
J. E. O'Brien; M. G. McKellar; E. A. Harvego; C. M. Stoots
2009-05-01
A research and development program is under way at the Idaho National Laboratory (INL) to assess the technological and scale-up issues associated with the implementation of solid-oxide electrolysis cell technology for efficient high-temperature hydrogen production from steam. This work is supported by the US Department of Energy, Office of Nuclear Energy, under the Nuclear Hydrogen Initiative. This paper will provide an overview of large-scale system modeling results and economic analyses that have been completed to date. System analysis results have been obtained using the commercial code UniSim, augmented with a custom high-temperature electrolyzer module. Economic analysis results were based on the DOE H2A analysis methodology. The process flow diagrams for the system simulations include an advanced nuclear reactor as a source of high-temperature process heat, a power cycle and a coupled steam electrolysis loop. Several reactor types and power cycles have been considered, over a range of reactor outlet temperatures. Pure steam electrolysis for hydrogen production as well as coelectrolysis for syngas production from steam/carbon dioxide mixtures have both been considered. In addition, the feasibility of coupling the high-temperature electrolysis process to biomass and coal-based synthetic fuels production has been considered. These simulations demonstrate that the addition of supplementary nuclear hydrogen to synthetic fuels production from any carbon source minimizes emissions of carbon dioxide during the production process.
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)
2003-04-08
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.
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)
2010-02-22
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.
1980-10-29
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.
Mitchell, John Anthony; Epp, David S.; Wittwer, Jonathan W.
2005-10-01
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.
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
Vallis, Geoff
would play a leading-order role in setting the channel stratification and hence (via thermal windThe Effects of Mesoscale Eddies on the Stratification and Transport of an Ocean with a Circumpolar in the channel are investigated. With small overlying winds, the channel stratification is largely set
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
Eddy current measurement of tube element spacing
Latham, Wayne Meredith (Forest, VA); Hancock, Jimmy Wade (Lynchburg, VA); Grut, Jayne Marie (Madison Heights, VA)
1998-01-01
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.
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
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
Large Scale DD Simulation Results for Crystal Plasticity Parameters in Fe-Cr And Fe-Ni Systems
Zbib, Hussein M.; Li, Dongsheng; Sun, Xin; Khaleel, Mohammad A.
2012-04-30
The development of viable nuclear energy source depends on ensuring structural materials integrity. Structural materials in nuclear reactors will operate in harsh radiation conditions coupled with high level hydrogen and helium production, as well as formation of high density of point defects and defect clusters, and thus will experience severe degradation of mechanical properties. Therefore, the main objective of this work is to develop a capability that predicts aging behavior and in-service lifetime of nuclear reactor components and, thus provide an instrumental tool for tailoring materials design and development for application in future nuclear reactor technologies. Towards this end goal, the long term effort is to develop a physically based multiscale modeling hierarchy, validated and verified, to address outstanding questions regarding the effects of irradiation on materials microstructure and mechanical properties during extended service in the fission and fusion environments. The focus of the current investigation is on modern steels for use in nuclear reactors including high strength ferritic-martensitic steels (Fe-Cr-Ni alloys). The effort is to develop a predicative capability for the influence of irradiation on mechanical behavior. Irradiation hardening is related to structural information crossing different length scales, such as composition, dislocation, and crystal orientation distribution. To predict effective hardening, the influence factors along different length scales should be considered. Therefore, a hierarchical upscaling methodology is implemented in this work in which relevant information is passed between models at three scales, namely, from molecular dynamics to dislocation dynamics to dislocation-based crystal plasticity. The molecular dynamics (MD) was used to predict the dislocation mobility in body centered cubic (bcc) Fe and its Ni and Cr alloys. The results are then passed on to dislocation dynamics to predict the critical resolved shear stress (CRSS) from the evolution of local dislocation and defects. In this report the focus is on the results obtained from large scale dislocation dynamics simulations. The effect of defect density, materials structure was investigated, and evolution laws are obtained. These results will form the bases for the development of evolution and hardening laws for a dislocation-based crystal plasticity framework. The hierarchical upscaling method being developed in this project can provide a guidance tool to evaluate performance of structural materials for next-generation nuclear reactors. Combined with other tools developed in the Nuclear Energy Advanced Modeling and Simulation (NEAMS) program, the models developed will have more impact in improving the reliability of current reactors and affordability of new reactors.
Eddy Current for Sizing Cracks in Canisters for Dry Storage of Used Nuclear Fuel
Meyer, Ryan M.; Jones, Anthony M.; Pardini, Allan F.
2014-01-01
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
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
Modeled biogeochemical responses to mesoscale eddies in the South China Sea
Xiu, Peng
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
Eddy-current-damped microelectromechanical switch
Christenson, Todd R. (Albuquerque, NM); Polosky, Marc A. (Tijeras, NM)
2009-12-15
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)
2007-10-30
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 heat fluxes at Drake Passage due to mesoscale motions
Rojas Recabal, Ricardo Luis
1982-01-01
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...
Qin, Hong; Xiao, Jianyuan; Zhang, Ruili; He, Yang; Wang, Yulei; Burby, Joshua W; Ellison, Leland; Zhou, Yao
2015-01-01
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.
Taucer, Philip Isaiah
2006-08-16
site with Juniperus ashei (ashe juniper) cover both before and after brush removal, with three replications of a particular rainfall event for each vegetation condition. Similar simulations were carried out on a plot with a longstanding grass cover...
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.
2010-08-01
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.
Mesoscale Eddies in the Gulf of Alaska: Observations and Implications
Rovegno, Peter
2012-01-01
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
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 ...
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.
2011-08-01
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.
GEOPHYSICAL RESEARCH LETTERS Supporting Information for "Eddy-mediated
Stewart, Andrew
GEOPHYSICAL RESEARCH LETTERS Supporting Information for "Eddy-mediated transport of warm, and over- turning circulation. 1 Department of Atmospheric and Oceanic Sciences, University of California, Los Angeles, Los Angeles, California, USA. 2 Environmental Sciences and Engineering, California
Eddy-mean flow interactions in western boundary current jets
Waterman, Stephanie N
2009-01-01
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 ...
Analysis of azimuthal mode dynamics of mesoscale eddies
McCalpin, John David
1984-01-01
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
2012-01-01
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
2015-01-01
We introduce project NIHAO (Numerical Investigation of a Hundred Astrophysical Objects), a set of 100 cosmological zoom-in hydrodynamical simulations performed using the GASOLINE code, with an improved implementation of the SPH algorithm. The haloes in our study range from dwarf to Milky Way masses, and represent an unbiased sampling of merger histories, concentrations and spin parameters. The particle masses and force softenings are chosen to resolve the mass profile to below 1% of the virial radius at all masses, ensuring that galaxy half-light radii are well resolved. Using the same treatment of star formation and stellar feedback for every object, the simulated galaxies reproduce the observed inefficiency of galaxy formation across cosmic time as expressed through the stellar mass vs halo mass relation, and the star formation rate vs stellar mass relation. We thus conclude that stellar feedback is the chief piece of physics required to limit the efficiency of star formation in galaxies less massive than t...
On Massively Parallel Simulation of Large-Scale Fat-Tree Networks for HPC Systems and Data Centers
Sun, Xian-He
Technologies (WEST), USA, June 2011. [4] N. Liu, X. Yang, X.-H. Sun, J. Jenkins, and R. Ross. Yarnsim://www.alcf.anl.gov/user-guides/mira-cetus-vesta Department of Computer Science, Illinois Institute of Technology, Chicago, Illinois.Ning Liu, Xian-He Sun statistic collector protocols routing algorithms simulated nodes 0% 20% 40% 60% 80% 100% 0 50 100 150 200
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
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 ...
Is it Cost-Effective to Replace Old Eddy-Current Drives? | Department...
Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site
Is it Cost-Effective to Replace Old Eddy-Current Drives? Is it Cost-Effective to Replace Old Eddy-Current Drives? New pulse-width-modulated (PWM) adjustable speed drives (ASDs) may...
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 ...
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)
2007-03-21
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.
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)
2004-12-01
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.
Windgenerated eddy characteristics in the lee of the island of Hawaii
Qiu, Bo
Click Here for Full Article Windgenerated eddy characteristics in the lee of the island of Hawaii to clarify the mesoscale eddy characteristics in the lee of the island of Hawaii, the largest island. In the immediate lee southwest of Hawaii (Region E), eddy signals have a predominant 60 day period and a short
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
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
Compensation for the Eddy Current Effect in the APS Storage Ring Vacuum Chamber
Kemner, Ken
Compensation for the Eddy Current Effect in the APS Storage Ring Vacuum Chamber Y. Chung Abstract inside the APS storage ring vacuum chamber due to the eddy current effect were measured. A circuit of the correction magnet field, externally applied to the vac- uum chamber, induces eddy current inside the aluminum
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
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.
2007-01-01
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
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
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
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
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 Scalable O(N) Algorithm for Large-Scale Parallel First-Principles Molecular Dynamics Simulations
Osei-Kuffuor, Daniel; Fattebert, Jean-Luc
2014-01-01
Traditional algorithms for first-principles molecular dynamics (FPMD) simulations only gain a modest capability increase from current petascale computers, due to their O(N^{3}) complexity and their heavy use of global communications. To address this issue, we are developing a truly scalable O(N) complexity FPMD algorithm, based on density functional theory (DFT), which avoids global communications. The computational model uses a general nonorthogonal orbital formulation for the DFT energy functional, which requires knowledge of selected elements of the inverse of the associated overlap matrix. We present a scalable algorithm for approximately computing selected entries of the inverse of the overlap matrix, based on an approximate inverse technique, by inverting local blocks corresponding to principal submatrices of the global overlap matrix. The new FPMD algorithm exploits sparsity and uses nearest neighbor communication to provide a computational scheme capable of extreme scalability. Accuracy is controlled by the mesh spacing of the finite difference discretization, the size of the localization regions in which the electronic orbitals are confined, and a cutoff beyond which the entries of the overlap matrix can be omitted when computing selected entries of its inverse. We demonstrate the algorithm's excellent parallel scaling for up to O(100K) atoms on O(100K) processors, with a wall-clock time of O(1) minute per molecular dynamics time step.
Optimisation of an idealised ocean model, stochastic parameterisation of sub-grid eddies
Fenwick C. Cooper; Laure Zanna
2014-10-21
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.
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
2010-02-22
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.
On the simulation of shock-driven material mixing in high-Re flows (u)
Grinstein, Fernando F [Los Alamos National Laboratory
2009-01-01
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.
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.
2015-03-27
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
2014-12-31
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.
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
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
2015-06-19
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
Nitao, J.J.
1989-11-06
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)
2014-12-01
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.
1994-08-01
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.
2013-10-01
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.
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)
2000-01-01
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
2006-08-01
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.
On the self-sustained nature of large-scale motions in turbulent Couette flow
Rawat, Subhandu; Hwang, Yongyun; Rincon, François
2015-01-01
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...
Method and apparatus for correcting eddy current signal voltage for temperature effects
Kustra, Thomas A. (N. Huntingdon, PA); Caffarel, Alfred J. (Pittsburgh, PA)
1990-01-01
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)
2001-01-01
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.
Is it Cost-Effective to Replace Old Eddy-Current Drives? - Motor Tip Sheet #12
2008-07-01
New pulse-width-modulated (PWM) adjustable speed drives (ASDs) may be cost-effective replacements for aging or maintenance-intensive eddy-current drives.
Is it Cost-Effective to Replace Old Eddy-Current Drives?
Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site
(PWM) variable frequency drives (VFD) may be cost- effective replacements for aging or high-maintenance eddy-current drives that are used with variable torque loads, such...
Usmanov, Arcadi V.; Matthaeus, William H.; Goldstein, Melvyn L.
2014-06-10
We have developed a three-fluid, three-dimensional magnetohydrodynamic solar wind model that incorporates turbulence transport, eddy viscosity, turbulent resistivity, and turbulent heating. The solar wind plasma is described as a system of co-moving solar wind protons, electrons, and interstellar pickup protons, with separate energy equations for each species. Numerical steady-state solutions of Reynolds-averaged solar wind equations coupled with turbulence transport equations for turbulence energy, cross helicity, and correlation length are obtained by the time relaxation method in the corotating with the Sun frame of reference in the region from 0.3 to 100 AU (but still inside the termination shock). The model equations include the effects of electron heat conduction, Coulomb collisions, photoionization of interstellar hydrogen atoms and their charge exchange with the solar wind protons, turbulence energy generation by pickup protons, and turbulent heating of solar wind protons and electrons. The turbulence transport model is based on the Reynolds decomposition and turbulence phenomenologies that describe the conversion of fluctuation energy into heat due to a turbulent cascade. In addition to using separate energy equations for the solar wind protons and electrons, a significant improvement over our previous work is that the turbulence model now uses an eddy viscosity approximation for the Reynolds stress tensor and the mean turbulent electric field. The approximation allows the turbulence model to account for driving of turbulence by large-scale velocity gradients. Using either a dipole approximation for the solar magnetic field or synoptic solar magnetograms from the Wilcox Solar Observatory for assigning boundary conditions at the coronal base, we apply the model to study the global structure of the solar wind and its three-dimensional properties, including embedded turbulence, heating, and acceleration throughout the heliosphere. The model results are compared with plasma and magnetic field observations on WIND, Ulysses, and Voyager 2 spacecraft.
Methods of and apparatus for levitating an eddy current probe
Stone, William J. (Kansas City, MO)
1988-05-03
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)
2014-02-18
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
2011-11-17
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, New Mexico: Energy Resources | Open Energy Information
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New Eddy Correlation System for ARM SGP Site
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AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Homesum_a_epg0_fpd_mmcf_m.xls" ,"Available from WebQuantityBonneville Power Administration wouldMass map shinesSolar Photovoltaic(MillionNatureThousand Cubic| DepartmentREAC/TS atNew Eddy
.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
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
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)
2011-06-23
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.
Are mesoscale eddies in shelf seas formed by baroclinic instability of tidal fronts?
Williams, Ric
Are mesoscale eddies in shelf seas formed by baroclinic instability of tidal fronts? G. Badin,1 R; accepted 23 July 2009; published 27 October 2009. [1] The formation of eddies along tidal fronts signals are dampened by air-sea interaction and eroded by wind and tidal mixing. High-resolution CTD
Qiu, Bo
flank of the wind jet and strengthens as it propagates offshore in the following two to three weeks Papagayo, ocean eddy formation is not well correlated with local wind jet variability. In both the GulfsEast Pacific ocean eddies and their relationship to subseasonal variability in Central American
Eddies as Offshore Foraging Grounds for Melon-headed Whales (Peponocephala electra)
Hawai'i at Manoa, University of
Eddies as Offshore Foraging Grounds for Melon- headed Whales (Peponocephala electra) Phoebe, NOAA 5School of Fisheries and Ocean Sciences, University of Alaska Fairbanks and Alaska SeaLife Center eddies occur frequently in the lee of the Hawaiian Islands Formed and sustained by easterly trade winds
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
A generalized likelihood ratio technique for automated analysis of bobbin coil eddy current dataq
Polikar, Robi
is positioned in a defect-free region of the tube, the differential im- pedance of the two coils is zeroA generalized likelihood ratio technique for automated analysis of bobbin coil eddy current dataq M presents a generalized likelihood ratio technique for detection of defect locations from bobbin coil eddy
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
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
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
Hot-cell design considerations for interfacing eddy-current systems
Franklin, E.M.; Webb, J.P.; Larson, J.M.
1985-01-01
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.
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
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
Direct numerical simulation of turbulent reacting flows
Chen, J.H. [Sandia National Laboratories, Livermore, CA (United States)
1993-12-01
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.
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
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
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.
2006-01-01
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
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
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.
2007-01-01
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
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
Deep-Sea Research I 53 (2006) 17181728 A North Atlantic deep-water eddy in the
Miami, University of
2006-01-01
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
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
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
Barnes, Elizabeth A.
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
Hartmann, Dennis
Rossby Wave Scales, Propagation, and the Variability of Eddy-Driven Jets ELIZABETH A. BARNES (Manuscript received 27 January 2011, in final form 12 April 2011) ABSTRACT The eddy-driven jet is located-driven jet. This work explores how the eddy-driven jet and its variability persist within these limits
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
The Pennsylvania State University Graduate School
. Large Eddy Simulations (LES) of the flow field around the National Renewable Energy Laboratory (NREL................................................................................................1 1.1 Motivation
The role of large eddy fluctuations in the Madison Dynamo Experiment
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
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Cremers, Daniel
, Eddy Ilg, Philip H¨ausser, Caner Hazirbas¸, Vladimir Golkov University of Freiburg Technical University
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
2000-01-01
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
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
Impact of mesoscale eddies on water transport between the Pacific Ocean and the Bering Sea
Prants, S V; Budyansky, M V; Uleysky, M Yu
2013-01-01
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...
Eddy Current Examination of Spent Nuclear Fuel Canister Closure Welds
Arthur D. Watkins; Dennis C. Kunerth; Timothy R. McJunkin
2006-04-01
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.
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)
2008-02-28
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.
Marino, Raffaele; Herbert, Corentin; Pouquet, Annick
2015-01-01
The interplay between waves and eddies in stably stratified rotating flows is investigated by means of world-class direct numerical simulations using up to $3072^3$ grid points. Strikingly, we find that the shift from vortex to wave dominated dynamics occurs at a wavenumber $k_R$ which does not depend on Reynolds number, suggesting that partition of energy between wave and vortical modes is not sensitive to the development of turbulence at the smaller scales. We also show that $k_R$ is comparable to the wavenumber at which exchanges between kinetic and potential modes stabilize at close to equipartition, emphasizing the role of potential energy, as conjectured in the atmosphere and the oceans. Moreover, $k_R$ varies as the inverse of the Froude number as explained by the scaling prediction proposed, consistent with recent observations and modeling of the Mesosphere-Lower Thermosphere and of the ocean.
Biases of CO2 Storage in Eddy Flux Measurements pertinent to...
Office of Scientific and Technical Information (OSTI)
Biases of CO2 Storage in Eddy Flux Measurements pertinent to Vertical Configurations of a Profile System and CO2 Density Averaging Citation Details In-Document Search Title: Biases...
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 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 ...
Zhang, Yang, Ph. D. Massachusetts Institute of Technology
2009-01-01
In this thesis, the influence of boundary layer processes and seasonal forcing on baroclinic eddy equilibration is studied to understand how the baroclinic adjustment is modified when taking into account these two factors. ...
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 ...
Modeling of transformers using circuit simulators
Archer, W.E.; Deveney, M.F.; Nagel, R.L.
1994-07-01
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.
Method for removal of random noise in eddy-current testing system
Levy, Arthur J. (Schenectady, NY)
1995-01-01
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.
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)
2010-02-22
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)
2007-03-21
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.
DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)
Wolfram, Phillip J.; Ringler, Todd D.; Maltrud, Mathew E.; Jacobsen, Douglas W.; Petersen, Mark R.
2015-08-01
Isopycnal diffusivity due to stirring by mesoscale eddies in an idealized, wind-forced, eddying, midlatitude ocean basin is computed using Lagrangian, in Situ, Global, High-Performance Particle Tracking (LIGHT). Simulation is performed via LIGHT within the Model for Prediction across Scales Ocean (MPAS-O). Simulations are performed at 4-, 8-, 16-, and 32-km resolution, where the first Rossby radius of deformation (RRD) is approximately 30 km. Scalar and tensor diffusivities are estimated at each resolution based on 30 ensemble members using particle cluster statistics. Each ensemble member is composed of 303 665 particles distributed across five potential density surfaces. Diffusivity dependence upon modelmore »resolution, velocity spatial scale, and buoyancy surface is quantified and compared with mixing length theory. The spatial structure of diffusivity ranges over approximately two orders of magnitude with values of O(105) m2 s–1 in the region of western boundary current separation to O(103) m2 s–1 in the eastern region of the basin. Dominant mixing occurs at scales twice the size of the first RRD. Model resolution at scales finer than the RRD is necessary to obtain sufficient model fidelity at scales between one and four RRD to accurately represent mixing. Mixing length scaling with eddy kinetic energy and the Lagrangian time scale yield mixing efficiencies that typically range between 0.4 and 0.8. In conclusion, a reduced mixing length in the eastern region of the domain relative to the west suggests there are different mixing regimes outside the baroclinic jet region.« less
Asaad, Sameh W; Bellofatto, Ralph E; Brezzo, Bernard; Haymes, Charles L; Kapur, Mohit; Parker, Benjamin D; Roewer, Thomas; Tierno, Jose A
2014-01-28
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.
Variable current speed controller for eddy current motors
Gerth, H.L.; Bailey, J.M.; Casstevens, J.M.; Dixon, J.H.; Griffith, B.O.; Igou, R.E.
1982-03-12
A speed control system for eddy current motors is provided in which the current to the motor from a constant frequency power source is varied by comparing the actual motor speed signal with a setpoint speed signal to control the motor speed according to the selected setpoint speed. A three-phase variable voltage autotransformer is provided for controlling the voltage from a three-phase power supply. A corresponding plurality of current control resistors is provided in series with each phase of the autotransformer output connected to inputs of a three-phase motor. Each resistor is connected in parallel with a set of normally closed contacts of plurality of relays which are operated by control logic. A logic circuit compares the selected speed with the actual motor speed obtained from a digital tachometer monitoring the motor spindle speed and operated the relays to add or substract resistance equally in each phase of the motor input to vary the motor current to control the motor at the selected speed.
Distance dependence of the phase signal in eddy current microscopy
Roll, Tino; Fischer, Ulrich; Schleberger, Marika
2008-01-01
Atomic force microscopy using a magnetic tip is a promising tool for investigating conductivity on the nano-scale. By the oscillating magnetic tip eddy currents are induced in the conducting parts of the sample which can be detected in the phase signal of the cantilever. However, the origin of the phase signal is still controversial because theoretical calculations using a monopole appoximation for taking the electromagnetic forces acting on the tip into account yield an effect which is too small by more than two orders of magnitude. In order to determine the origin of the signal we used especially prepared gold nano patterns embedded in a non-conducting polycarbonate matrix and measured the distance dependence of the phase signal. Our data clearly shows that the interacting forces are long ranged and therefore, are likely due to the electromagnetic interaction between the magnetic tip and the conducting parts of the surface. Due to the long range character of the interaction a change in conductivity of $\\Del...
Verde Salas, Alexander José
2014-04-28
to injection – Case 3. ......... 89 6.4. Fluid injection and production in large-scale poroelastic shales – Case 4. ........... 92 7. CONCLUSIONS AND RECOMMENDATIONS ....................................................... 99 7.1. Conclusions...). The displacement discontinuity, Di, is defined as the difference in displacement between the two sides of the segment as: ? ? ? ? snixuxuD iii ,0,0, 11 ??? ?? (2-1) The fundamental solutions provide expressions to compute the induced stresses (?xx, ?yy...