The Experts below are selected from a list of 267 Experts worldwide ranked by ideXlab platform
P W Mckenty - One of the best experts on this subject based on the ideXlab platform.
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monte carlo charged particle tracking and energy deposition on a Lagrangian Mesh
Physical Review E, 2005Co-Authors: J Yuan, G A Moses, P W MckentyAbstract:A Monte Carlo algorithm for alpha particle tracking and energy deposition on a RZ cylindrical computational Mesh in a Lagrangian hydrodynamics code used for inertial confinement fusion (ICF) simulations is presented. The straight line approximation is used to follow propagation of 'Monte Carlo particles' which represent collections of alpha particles generated from thermonuclear deuterium-tritium (DT) reactions. Energy deposition in the plasma is modeled by the continuous slowing down approximation. The scheme addresses various aspects arising in the coupling of Monte Carlo tracking with Lagrangian hydrodynamics; such as non-orthogonal severely distorted Mesh cells, particle relocation on the moving Mesh and particle relocation after rezoning. A comparison with the flux-limited multi-group diffusion transport method is presented for a polar direct drive target design for the National Ignition Facility. Simulations show the Monte Carlo transport method predicts about 30 picosecond earlier ignition than predicted by the diffusion method, and generates higher hot spot temperature. Nearly linear speed-up is achieved for multi-processor parallel simulations.
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Monte Carlo charged-particle tracking and energy deposition on a Lagrangian Mesh.
Physical review. E Statistical nonlinear and soft matter physics, 2005Co-Authors: J Yuan, G A Moses, P W MckentyAbstract:A Monte Carlo algorithm for alpha particle tracking and energy deposition on a cylindrical computational Mesh in a Lagrangian hydrodynamics code used for inertial confinement fusion (ICF) simulations is presented. The straight line approximation is used to follow propagation of "Monte Carlo particles" which represent collections of alpha particles generated from thermonuclear deuterium-tritium (DT) reactions. Energy deposition in the plasma is modeled by the continuous slowing down approximation. The scheme addresses various aspects arising in the coupling of Monte Carlo tracking with Lagrangian hydrodynamics; such as non-orthogonal severely distorted Mesh cells, particle relocation on the moving Mesh and particle relocation after rezoning. A comparison with the flux-limited multi-group diffusion transport method is presented for a polar direct drive target design for the National Ignition Facility. Simulations show the Monte Carlo transport method predicts about earlier ignition than predicted by the diffusion method, and generates higher hot spot temperature. Nearly linear speed-up is achieved for multi-processor parallel simulations.
Roberto Verzicco - One of the best experts on this subject based on the ideXlab platform.
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a fast moving least squares approximation with adaptive Lagrangian Mesh refinement for large scale immersed boundary simulations
Journal of Computational Physics, 2018Co-Authors: Vamsi Spandan, Detlef Lohse, Marco D De Tullio, Roberto VerziccoAbstract:Abstract In this paper we propose and test the validity of simple and easy-to-implement algorithms within the immersed boundary framework geared towards large scale simulations involving thousands of deformable bodies in highly turbulent flows. First, we introduce a fast moving least squares (fast-MLS) approximation technique with which we speed up the process of building transfer functions during the simulations which leads to considerable reductions in computational time. We compare the accuracy of the fast-MLS against the exact moving least squares (MLS) for the standard problem of uniform flow over a sphere. In order to overcome the restrictions set by the resolution coupling of the Lagrangian and Eulerian Meshes in this particular immersed boundary method, we present an adaptive Lagrangian Mesh refinement procedure that is capable of drastically reducing the number of required nodes of the basic Lagrangian Mesh when the immersed boundaries can move and deform. Finally, a coarse-grained collision detection algorithm is presented which can detect collision events between several Lagrangian markers residing on separate complex geometries with minimal computational overhead.
Ronald Fedkiw - One of the best experts on this subject based on the ideXlab platform.
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semi implicit surface tension formulation with a Lagrangian surface Mesh on an eulerian simulation grid
Journal of Computational Physics, 2012Co-Authors: Craig Schroeder, Wen Zheng, Ronald FedkiwAbstract:We present a method for applying semi-implicit forces on a Lagrangian Mesh to an Eulerian discretization of the Navier Stokes equations in a way that produces a sparse symmetric positive definite system. The resulting method has semi-implicit and fully-coupled viscosity, pressure, and Lagrangian forces. We apply our new framework for forces on a Lagrangian Mesh to the case of a surface tension force, which when treated explicitly leads to a tight time step restriction. By applying surface tension as a semi-implicit Lagrangian force, the resulting method benefits from improved stability and the ability to take larger time steps. The resulting discretization is also able to maintain parasitic currents at low levels.
J Yuan - One of the best experts on this subject based on the ideXlab platform.
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monte carlo charged particle tracking and energy deposition on a Lagrangian Mesh
Physical Review E, 2005Co-Authors: J Yuan, G A Moses, P W MckentyAbstract:A Monte Carlo algorithm for alpha particle tracking and energy deposition on a RZ cylindrical computational Mesh in a Lagrangian hydrodynamics code used for inertial confinement fusion (ICF) simulations is presented. The straight line approximation is used to follow propagation of 'Monte Carlo particles' which represent collections of alpha particles generated from thermonuclear deuterium-tritium (DT) reactions. Energy deposition in the plasma is modeled by the continuous slowing down approximation. The scheme addresses various aspects arising in the coupling of Monte Carlo tracking with Lagrangian hydrodynamics; such as non-orthogonal severely distorted Mesh cells, particle relocation on the moving Mesh and particle relocation after rezoning. A comparison with the flux-limited multi-group diffusion transport method is presented for a polar direct drive target design for the National Ignition Facility. Simulations show the Monte Carlo transport method predicts about 30 picosecond earlier ignition than predicted by the diffusion method, and generates higher hot spot temperature. Nearly linear speed-up is achieved for multi-processor parallel simulations.
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Monte Carlo charged-particle tracking and energy deposition on a Lagrangian Mesh.
Physical review. E Statistical nonlinear and soft matter physics, 2005Co-Authors: J Yuan, G A Moses, P W MckentyAbstract:A Monte Carlo algorithm for alpha particle tracking and energy deposition on a cylindrical computational Mesh in a Lagrangian hydrodynamics code used for inertial confinement fusion (ICF) simulations is presented. The straight line approximation is used to follow propagation of "Monte Carlo particles" which represent collections of alpha particles generated from thermonuclear deuterium-tritium (DT) reactions. Energy deposition in the plasma is modeled by the continuous slowing down approximation. The scheme addresses various aspects arising in the coupling of Monte Carlo tracking with Lagrangian hydrodynamics; such as non-orthogonal severely distorted Mesh cells, particle relocation on the moving Mesh and particle relocation after rezoning. A comparison with the flux-limited multi-group diffusion transport method is presented for a polar direct drive target design for the National Ignition Facility. Simulations show the Monte Carlo transport method predicts about earlier ignition than predicted by the diffusion method, and generates higher hot spot temperature. Nearly linear speed-up is achieved for multi-processor parallel simulations.
Craig Schroeder - One of the best experts on this subject based on the ideXlab platform.
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semi implicit surface tension formulation with a Lagrangian surface Mesh on an eulerian simulation grid
Journal of Computational Physics, 2012Co-Authors: Craig Schroeder, Wen Zheng, Ronald FedkiwAbstract:We present a method for applying semi-implicit forces on a Lagrangian Mesh to an Eulerian discretization of the Navier Stokes equations in a way that produces a sparse symmetric positive definite system. The resulting method has semi-implicit and fully-coupled viscosity, pressure, and Lagrangian forces. We apply our new framework for forces on a Lagrangian Mesh to the case of a surface tension force, which when treated explicitly leads to a tight time step restriction. By applying surface tension as a semi-implicit Lagrangian force, the resulting method benefits from improved stability and the ability to take larger time steps. The resulting discretization is also able to maintain parasitic currents at low levels.
