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We present a more accurate numerical scheme for the calculation of diffusive shock acceleration of cosmic rays using Stochastic Differential Equations. The accuracy of this scheme is demonstrated using a simple analytical flow profile that…

High Energy Astrophysical Phenomena · Physics 2011-03-17 A. Achterberg , K. M. Schure

In the paper, we propose a new effective mathematical formulation and resulting universal numerical algorithm capable of tackling various HF models in the framework of a unified approach. The presented numerical scheme is not limited to any…

Fluid Dynamics · Physics 2015-04-23 Michal Wrobel , Gennady Mishuris

In this paper, we study the problem of computing the effective diffusivity for particles moving in chaotic flows. Instead of solving a convection-diffusion type cell problem in the Eulerian formulation (arising from homogenization theory…

Numerical Analysis · Mathematics 2020-12-17 Zhongjian Wang , Jack Xin , Zhiwen Zhang

We develop a relativistic lattice Boltzmann model capable of describing relativistic fluid dynamics at ultra-high velocities, with Lorentz factors up to $\gamma \sim 10$. To this purpose, we first build a new lattice kinetic scheme by…

High Energy Astrophysical Phenomena · Physics 2015-06-12 F. Mohseni , M. Mendoza , S. Succi , H. J. Herrmann

A universal particle velocity based algorithm for simulating hydraulic fracture with leak-off, previously demonstrated for the PKN and KGD models, is extended to obtain solutions for a penny-shaped crack. The numerical scheme is capable of…

Geophysics · Physics 2018-11-15 Daniel Peck , Michel Wrobel , Monika Perkowska , Gennady Mishuris

To simulate the dynamics of fluid with polydisperse particles on macroscale level, one has to solve hydrodynamic equations with several relaxation terms, representing momentum transfer from fluid to particles and vice versa. For small…

Relativistic shocks accelerate particles by the first order Fermi mechanism. These particles then emit synchrotron emission in the post shock gas. We have developed a numerical code which integrates the relativistic Euler equations for…

Astrophysics · Physics 2009-11-06 T. P. Downes , P. Duffy , S. Komissarov

Accurate mesh-free simulation of fluid flows involving complex boundaries requires that the boundaries be captured accurately in terms of particles. In the context of incompressible/weakly-compressible fluid flow, the SPH method is more…

Computational Physics · Physics 2021-05-06 Pawan Negi , Prabhu Ramachandran

We present results from a Monte Carlo simulation of a parallel collisionless shock undergoing particle acceleration. Our simulation, which contains parameterized scattering and a particular thermal leakage injection model, calculates the…

Space Physics · Physics 2015-06-17 Donald C. Ellison , Donald C. Warren , Andrei M. Bykov

We review recent progress on collisionless relativistic shocks. Kinetic instability theory is briefed including its predictions and limitations. The main focus is on numerical experiments in (i) pair and (ii) electron-nucleon plasmas. The…

High Energy Astrophysical Phenomena · Physics 2011-10-20 A. M. Bykov , R. A. Treumann

A general, fast, and effective approach is developed for numerical calculation of kinetic plasma dispersion relations. The plasma dispersion function is approximated by $J$-pole expansion. Subsequently, the dispersion relation is…

Plasma Physics · Physics 2016-02-18 Hua-sheng Xie , Yong Xiao

We consider the simulation of isentropic flow in pipelines and pipe networks. Standard operating conditions in pipe networks suggest an emphasis to simulate low Mach and high friction regimes -- however, the system is stiff in these regimes…

Numerical Analysis · Mathematics 2025-07-22 Michael Redle , Michael Herty

An "exact" method for scalar one-dimensional hyperbolic conservation laws is presented. The approach is based on the evolution of shock particles, separated by local similarity solutions. The numerical solution is defined everywhere, and is…

Numerical Analysis · Mathematics 2023-08-17 Yossi Farjoun , Benjamin Seibold

Generalization of the self-similar solution for ultrarelativistic shock waves (Blandford & McKee, 1976) is obtained in presence of losses localized on the shock front or distributed in the downstream medium. It is shown that there are two…

Astrophysics · Physics 2007-05-23 E. V. Derishev , Vl. V. Kocharovsky , K. A. Martiyanov

This paper introduces a framework for simulating finite dimensional representations of (jump) diffusion sample paths over finite intervals, without discretisation error (exactly), in such a way that the sample path can be restored at any…

Methodology · Statistics 2016-02-10 Murray Pollock , Adam M. Johansen , Gareth O. Roberts

Based on the particle-in-cell (PIC) plasma simulation method, the speed-limited PIC (SLPIC) method delivers faster kinetic plasma simulation in cases where the particle distributions evolve slowly compared with the maximum stable PIC…

Computational Physics · Physics 2019-01-09 Gregory R. Werner , Thomas G. Jenkins , Andrew M. Chap , John R. Cary

We have developed a new, very efficient numerical scheme to solve the CR diffusion convection equation that can be applied to the study of the nonlinear time evolution of CR modified shocks for arbitrary spatial diffusion properties. The…

Astrophysics · Physics 2009-11-11 T. W. Jones , H. Kang

Immersed boundary-lattice Boltzmann method (IB-LBM) has been widely used for simulation of particle-laden flows recently. However, it was limited to small-scale simulations with no more than O(103) particles. Here, we expand IB-LBM for…

Computational Physics · Physics 2020-02-21 Maoqiang Jiang , Jing Li , Zhaohui Liu

The paper presents a solution for axisymmetric propagation of a penny-shaped crack driven by a thinning fluid. The solution to the accuracy of four significant digits, at least, is obtained on the basis of the modified formulation of…

Fluid Dynamics · Physics 2015-09-03 Aleksandr Linkov

Physical processes ranging from the Lamb shift to the energy loss dE/dx of a charged particle traversing a plasma entail processes that occur over a wide range of energy or length scales. Different physical mechanisms dominate at one or the…

Plasma Physics · Physics 2009-10-31 Lowell S. Brown