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Kinetic Turbulence Simulations at Extreme Scale on Leadership-Class Systems

by Bei Wang , Stephane Ethier , William Tang , Timothy Williams , Khaled Z Ibrahim , Kamesh Madduri , Samuel Williams , Leonid Oliker
"... ABSTRACT Reliable predictive simulation capability addressing confinement properties in magnetically confined fusion plasmas is critically-important for ITER, a 20 billion dollar international burning plasma device under construction in France. The complex study of kinetic turbulence, which can sev ..."
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severely limit the energy confinement and impact the economic viability of fusion systems, requires simulations at extreme scale for such an unprecedented device size. Our newly optimized, global, ab initio particle-in-cell code solving the nonlinear equations underlying gyrokinetic theory achieves

Turbulent kinetic energy budgets from a large-eddy simulation of airflow above and within a forest canopy

by Michael J. Dwyer, Edward G. Patton, Roger H. Shaw - Bound.-Layer Meteor , 1997
"... Abstract. The output of a large-eddy simulation was used to study the terms of the turbulent kinetic energy (TKE) budget for the air layers above and within a forest. The computation created a three-dimensional, time-dependent simulation of the airflow, in which the lowest third of the domain was oc ..."
Abstract - Cited by 22 (4 self) - Add to MetaCart
Abstract. The output of a large-eddy simulation was used to study the terms of the turbulent kinetic energy (TKE) budget for the air layers above and within a forest. The computation created a three-dimensional, time-dependent simulation of the airflow, in which the lowest third of the domain

QUASI-HYDRODYNAMIC MODEL AND SMALL SCALE TURBULENCE

by Boris Chetverushkin, Ilya Ivakhnenko, Sergey Polyakov , 2007
"... Abstract. The averaged quasi-hydrodynamic (QHD) system of equations describing small-scale turbulence and its implementation is presented. The QHD equations differ from the Navier-Stokes ones by additional dissipative terms. For low and middle speed flows these terms are related to the molecular vis ..."
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Abstract. The averaged quasi-hydrodynamic (QHD) system of equations describing small-scale turbulence and its implementation is presented. The QHD equations differ from the Navier-Stokes ones by additional dissipative terms. For low and middle speed flows these terms are related to the molecular

Advanced Lagrangian Simulation Algorithms for Magnetized Plasma Turbulence

by Ingmar Bert Broemstrup, Ingmar Bert Broemstrup , 2008
"... Nonlinear processes in hot, magnetized plasma are notoriously difficult to un-derstand without the use of numerical simulations. In recent decades, first principles, kinetic simulations have been widely and successfully used to study plasma turbu-lence and reconnection in weakly collisional systems. ..."
Abstract - Cited by 2 (1 self) - Add to MetaCart
Nonlinear processes in hot, magnetized plasma are notoriously difficult to un-derstand without the use of numerical simulations. In recent decades, first principles, kinetic simulations have been widely and successfully used to study plasma turbu-lence and reconnection in weakly collisional systems

RESPONSE OF A TETHERED AEROSTAT TO SIMULATED TURBULENCE

by Keith A Stanney Graduate , Research Assistant , Professor Christopher D Rahn
"... ABSTRACT Aerostats are lighter-than-air vehicles tethered to the ground by a cable and used for broadcasting, communications, surveillance, and drug interdiction. The dynamic response of tethered aerostats subject to extreme atmospheric turbulence often dictates survivability. This paper develops a ..."
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a theoretical model that predicts the planar response of a tethered aerostat subject to atmospheric turbulence and simulates the response to 1000 simulated hurricane scale turbulent time histories. The aerostat dynamic model assumes the aerostat hull to be a rigid body with nonlinear fluid loading

TURBULENCE KINETIC ENERGY AND DISSIPATION RATE ESTIMATED FROM A VIRTUAL WIND PROFILER AND VERIFIED THROUGH LARGE EDDY SIMULATIONS

by D. E. Scipión, E. Fedorovich, R. D. Palmer, P. B. Chilson, A. M. Botnick
"... Values of turbulence kinetic energy (TKE) and TKE dis-sipation rate can be obtained from radar estimates of velocity and Doppler spectral width. However, these es-timates usually do not have sufficient temporal resolu-tion and lead to filtered results that do not allow straight-forward theoretical i ..."
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Values of turbulence kinetic energy (TKE) and TKE dis-sipation rate can be obtained from radar estimates of velocity and Doppler spectral width. However, these es-timates usually do not have sufficient temporal resolu-tion and lead to filtered results that do not allow straight-forward theoretical

Shear-Improved Smagorinsky Model for Large-Eddy Simulation of Wall-Bounded Turbulent Flows

by E. Lévêque, F. Toschi, L. Shao, J.-P. Bertoglio - UNDER CONSIDERATION FOR PUBLICATION IN J. FLUID MECH. , 2006
"... A shear-improved Smagorinsky model is introduced based on recent results concerning mean-shear effects in wall-bounded turbulence by Toschi et al. (2000). The Smagorinsky eddy-viscosity is modified as νT = (Cs∆) 2(|S | − |〈S〉|): the magnitude of the mean shear |〈S〉 | is subtracted from the magnitud ..."
Abstract - Cited by 19 (4 self) - Add to MetaCart
Smagorinsky model and direct numerical simulations for mean velocity, turbulent kinetic energy and Reynolds stress profiles, are shown to be extremely satisfactory. The proposed model, in addition of being physically sound and consistent with the scale-by-scale energy budget of locally homogeneous shear

PLASMA BETA DEPENDENCE OF THE ION-SCALE SPECTRAL BREAK OF SOLAR WIND TURBULENCE: HIGH-RESOLUTION 2D HYBRID SIMULATIONS

by Luca Franci , Simone Landi , Lorenzo Matteini , Andrea Verdini , Petr Hellinger
"... ABSTRACT We investigate properties of the ion-scale spectral break of solar wind turbulence by means of two-dimensional high-resolution hybrid particle-in-cell simulations. We impose an initial ambient magnetic field perpendicular to the simulation box and add a spectrum of in-plane, large-scale, m ..."
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, magnetic and kinetic fluctuations. We perform a set of simulations with different values of the plasma β, distributed over three orders of magnitude, from 0.01 to 10. In allcases, once turbulence is fully developed, we observe a power-law spectrum of the fluctuating magnetic field on large scales (in

Dynamo generated turbulence and large scale magnetic fields in a Keplerian shear flow

by Axel Brandenburg, Åke Nordlund, Robert F. Stein, Ulf Torkelsson , 1994
"... The nonlinear evolution of magnetized Keplerian shear flows is simulated in a local, three-dimensional model, including the effects of compressibility and stratification. Supersonic flows are initially generated by the Balbus-Hawley magnetic shear instability. The resulting flows regenerate a turbul ..."
Abstract - Cited by 18 (13 self) - Add to MetaCart
turbulent magnetic field which, in turn, reinforces the turbulence. Thus, the system acts like a dynamo that generates its own turbulence. However, unlike usual dynamos, the magnetic energy exceeds the kinetic energy of the turbulence by a factor of 3--10. By assuming the field to be vertical on the outer

Global MHD Modelling of the ISM- From large towards small scale turbulence

by K. T. Chy˙zy, R. -j. Dettmar, K. Otmianowska-mazur, M. Soida, Miguel A. De Avillez, Dieter Breitschwerdt , 2005
"... Dealing numerically with the turbulent nature and non-linearity of the physical processes involved in the ISM requires the use of sophisticated numerical schemes coupled to HD and MHD mathematical models. SNe are the main drivers of the interstellar turbulence by transferring kinetic energy into the ..."
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into the system. This energy is dissipated by shocks (which is more efficient) and by molecular viscosity. We carried out adaptive mesh refinement simulations (with a finest resolution of 0.625 pc) of the turbulent ISM embedded in a magnetic field with mean field components of 2 and 3 µG. The time scale of our
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