The Experts below are selected from a list of 162723 Experts worldwide ranked by ideXlab platform
I. V. Fryazinov - One of the best experts on this subject based on the ideXlab platform.
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method of adaptive artificial viscosity for Gas Dynamics equations on triangular and tetrahedral grids
Mathematical Models and Computer Simulations, 2013Co-Authors: I. V. Popov, I. V. FryazinovAbstract:In studies [1–7] a method of adaptive artificial viscosity (AAV) was proposed for the solution of Gas Dynamics equations. In this paper, this method is extended to the case of triangular grids for two-dimensional (2D) equations in the variables x, y, and r, z, and of tetrahedral grids for equations in Cartesian variables x, y, and z. The calculation results for the test problems are presented.
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Finite-difference method for computation of 3-D Gas Dynamics equations with artificial viscosity
Mathematical Models and Computer Simulations, 2011Co-Authors: I. V. Popov, I. V. FryazinovAbstract:A new numerical method for the solution of Gas Dynamics problems for three-dimensional (3D) systems in Eulerian variables is presented in the paper. The proposed method uses the approximation O (τ^2 + h _ x ^2 + h _ y ^2 + h _ z ^2 ) in the areas of the solution’s smoothness and beyond the compression waves; τ is the time step; and h _ x , h _ y , and h _ z are space variable steps. In the proposed difference scheme, in addition to Lax-Wendroff corrections, artificial viscosity μ that monotonizes the scheme is introduced. The viscosity is obtained from the conditions of the maximum principle. The results of the computation of the 3D test problem for the Euler equation are presented.
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adaptive artificial viscosity for multidimensional Gas Dynamics for euler variables in cartesian coordinates
Mathematical Models and Computer Simulations, 2010Co-Authors: I. V. Popov, I. V. FryazinovAbstract:A method of adaptive artificial viscosity (AAV2D-3D) for the solution of two-and three-dimensional equations of Gas Dynamics for Euler variables in the Cartesian coordinates system is considered. This paper continues works [1, 2]. The computational scheme is described in detail and the results of the test case are given.
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finite difference method for solving Gas Dynamics equations using adaptive artificial viscosity
Mathematical Models and Computer Simulations, 2009Co-Authors: I. V. Popov, I. V. FryazinovAbstract:A finite-difference method is proposed for solving Gas Dynamics equations, i.e., a homogeneous, monotonous finite-difference scheme of the second- order time approximation and space variables outside the areas of discontinuities and compression waves. A new way to introduce adaptive artificial viscosity (AAV) in a difference scheme is considered. The stability of the proposed difference scheme is numerically studied. Test calculations are presented for the motion of contact discontinuities, blast waves, and disintegration of discontinuities.
Wancheng Sheng - One of the best experts on this subject based on the ideXlab platform.
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Delta wave and vacuum state for generalized Chaplygin Gas Dynamics system as pressure vanishes
Nonlinear Analysis: Real World Applications, 2015Co-Authors: Wancheng Sheng, Guojuan Wang, Gan YinAbstract:Abstract This paper is concerned with the Riemann problems for the system of generalized Chaplygin Gas Dynamics and the formation of Delta wave and vacuum state as pressure vanishes. It is proved that, the limit solutions tend to the two kinds of Riemann solutions to the transport equations in zero-pressure flow, which include a Delta wave formed by a weighted δ -measure and a vacuum state.
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the general riemann problem for the linearized system of two dimensional isentropic flow in Gas Dynamics
Journal of Mathematical Analysis and Applications, 2002Co-Authors: Tatsian Li, Wancheng ShengAbstract:In this paper, we give the explicit solution to the general Riemann problem for the linearized system of two-dimensional isentropic flow in Gas Dynamics.
Pierrelouis Lions - One of the best experts on this subject based on the ideXlab platform.
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existence and stability of entropy solutions for the hyperbolic systems of isentropic Gas Dynamics in eulerian and lagrangian coordinates
Communications on Pure and Applied Mathematics, 1998Co-Authors: Pierrelouis Lions, Benoit Perthame, Panagiotis E SouganidisAbstract:We prove the existence and compactness (stability) of entropy solutions for the hyperbolic systems of conservation laws corresponding to the isentropic Gas Dynamics, where the pressure and density are related by a γ-law, for any γ > 1. Our results considerably extend and simplify the program initiated by DiPerna and provide a complete existence proof. Our methods are based on the compensated compactness and the kinetic formulation of systems of conservation laws. © 1996 John Wiley & Sons, Inc.
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kinetic formulation of the isentropic Gas Dynamics and p systems
Communications in Mathematical Physics, 1994Co-Authors: Pierrelouis Lions, Benoit Perthame, Eitan TadmorAbstract:We consider the 2 x 2 hyperbolic system of isentropic Gas Dynamics, in both Eulerian or Lagrangian variables (also called the p-system). We show that they can be reformulated as a kinetic equation, using an additional kinetic variable. Such a formulation was first obtained by the authors in the case of multidimensio nal scalar conservation laws. A new phenomenon occurs here, namely that the advection velocity is now a combination of the macroscopic and kinetic velocities. Various applications are given: we recover the invariant regions, deduce new L°° estimates using moments lemma and prove L°° — w* stability for 7 > 3.
Jonathan D Henshaw - One of the best experts on this subject based on the ideXlab platform.
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when Gas Dynamics decouples from galactic rotation characterizing ism circulation in disk galaxies
The Astrophysical Journal, 2020Co-Authors: Jose Utreras, Guillermo A Blanc, Andres Escala, Sharon E Meidt, Eric Emsellem, Frank Bigiel, Simon C O Glover, Jonathan D HenshawAbstract:In galactic disks, galactic rotation sets the bulk motion of Gas, and its energy and momentum can be transferred toward small scales. Additionally, in the interstellar medium, random and noncircular motions arise from stellar feedback, cloud-cloud interactions, and instabilities, among other processes. Our aim is to comprehend to which extent small-scale Gas Dynamics is decoupled from galactic rotation. We study the relative contributions of galactic rotation and local noncircular motions to the circulation of Gas, $\Gamma$, a macroscopic measure of local rotation, defined as the line integral of the velocity field around a closed path. We measure the circulation distribution as a function of spatial scale in a set of simulated disk galaxies and we model the velocity field as the sum of galactic rotation and a Gaussian random field. The random field is parameterized by a broken power law in Fourier space, with a break at the scale $\lambda_c$. We define the spatial scale $\lambda_{\rm eq}$ at which galactic rotation and non-circular motions contribute equally to $\Gamma$. For our simulated galaxies, the Gas Dynamics at the scale of molecular clouds is usually dominated by noncircular motions, but in the center of galactic disks galactic rotation is still relevant. Our model shows that the transfer of rotation from large scales breaks at the scale $\lambda_c$ and this transition is necessary to reproduce the circulation distribution. We find that $\lambda_{\rm eq}$, and therefore the structure of the Gas velocity field, is set by the local conditions of gravitational stability and stellar feedback.
Guillermo A Blanc - One of the best experts on this subject based on the ideXlab platform.
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when Gas Dynamics decouples from galactic rotation characterizing ism circulation in disk galaxies
The Astrophysical Journal, 2020Co-Authors: Jose Utreras, Guillermo A Blanc, Andres Escala, Sharon E Meidt, Eric Emsellem, Frank Bigiel, Simon C O Glover, Jonathan D HenshawAbstract:In galactic disks, galactic rotation sets the bulk motion of Gas, and its energy and momentum can be transferred toward small scales. Additionally, in the interstellar medium, random and noncircular motions arise from stellar feedback, cloud-cloud interactions, and instabilities, among other processes. Our aim is to comprehend to which extent small-scale Gas Dynamics is decoupled from galactic rotation. We study the relative contributions of galactic rotation and local noncircular motions to the circulation of Gas, $\Gamma$, a macroscopic measure of local rotation, defined as the line integral of the velocity field around a closed path. We measure the circulation distribution as a function of spatial scale in a set of simulated disk galaxies and we model the velocity field as the sum of galactic rotation and a Gaussian random field. The random field is parameterized by a broken power law in Fourier space, with a break at the scale $\lambda_c$. We define the spatial scale $\lambda_{\rm eq}$ at which galactic rotation and non-circular motions contribute equally to $\Gamma$. For our simulated galaxies, the Gas Dynamics at the scale of molecular clouds is usually dominated by noncircular motions, but in the center of galactic disks galactic rotation is still relevant. Our model shows that the transfer of rotation from large scales breaks at the scale $\lambda_c$ and this transition is necessary to reproduce the circulation distribution. We find that $\lambda_{\rm eq}$, and therefore the structure of the Gas velocity field, is set by the local conditions of gravitational stability and stellar feedback.
