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We determine the spectrum of particles accelerated at shocks with arbitrary speed and arbitrary scattering properties for different choices of the equation of state of the downstream plasma. More specifically we consider the effect of…

Astrophysics · Physics 2009-11-13 G. Morlino , P. Blasi , M. Vietri

A discrete-time totally asymmetric simple exclusion process on a lattice with open boundaries is considered. There are particles of different types. The type of a particle is characterized by the probability that a particle moves to a…

Statistical Mechanics · Physics 2025-11-04 Marina V. Yashina , Alexander G. Tatashev

In this paper, we study shock structures of collisionless shocks in partially ionized plasmas by means of two-dimensional hybrid simulations, where the shock is a perpendicular shock with shock velocity Vsh ~ 40 Va ~ 1333 km/s and the…

High Energy Astrophysical Phenomena · Physics 2016-02-03 Yutaka Ohira

This is the first of two papers examining the critical collapse of spherically symmetric perfect fluids with the equation of state P = (Gamma -1)rho. Here we present the equations of motion and describe a computer code capable of simulating…

General Relativity and Quantum Cosmology · Physics 2014-11-17 David W. Neilsen , Matthew W. Choptuik

The wide use of a speed-independent distance as a cut-off impact parameter together with Rutherford's scattering formula, within the cut-off theory, to account for charge screening in plasma environment embodies a clear inconsistency. A new…

Plasma Physics · Physics 2018-03-14 Mofreh R. Zaghloul

We consider moving particles in media with nonlinear friction and drive them by an asymmetric dichotomic Markov process. Due to different energy dissipations, during the forward and backward stroke, we obtain a mean non-vanishing directed…

Statistical Mechanics · Physics 2011-05-18 Gökan Cebiroglu , Christian Weber , Lutz Schimansky-Geier

We propose a time discretization scheme for a class of ordinary differential equations arising in simulations of fluid/particle flows. The scheme is intended to work robustly in the lubrication regime when the distance between two particles…

Numerical Analysis · Mathematics 2010-03-25 Matthieu Hillairet , Alexei Lozinski , Marcela Szopos

We develop a new numerical scheme for solving the radiative transfer equation in a spherically symmetric system. This scheme does not rely on any kind of diffusion approximation and it is accurate for optically thin, thick, and intermediate…

Instrumentation and Methods for Astrophysics · Physics 2018-05-31 Torsten Stamer , Shu-ichiro Inutsuka

We consider the acceleration of charged particles in relativistic shearing flows, with Lorentz factor up to $\Gamma_0 \sim 20$. We present numerical solutions to the particle transport equation and compare these with results from analytical…

High Energy Astrophysical Phenomena · Physics 2022-07-20 Frank M. Rieger , Peter Duffy

In this paper we present a novel algorithm for simulating geometrical flows, and in particular the Willmore flow, with conservation of volume and area. The idea is to adapt the class of diffusion-redistanciation algorithms to the Willmore…

Numerical Analysis · Mathematics 2021-08-30 Thibaut Metivet , Arnaud Sengers , Mourad Ismaïl , Emmanuel Maitre

A new algorithm has been developed to compute low Mach Numbers supercritical fluid flows. The algorithm is applied using a finite volume method based on the SIMPLER algorithm. Its main advantages are to decrease significantly the CPU time,…

Classical Physics · Physics 2007-08-21 Jalil Ouazzani , Yves Garrabos

We investigate ways of accurately simulating the propagation of energetic charged particles over small times where the standard Monte Carlo approximation to diffusive transport breaks down. We find that a small-angle scattering procedure…

Astrophysics · Physics 2009-11-07 R. J. Protheroe , A. Meli , A. -C Donea

We describe an algorithm that computes the linear dispersion relation of waves and instabilities in relativistic plasmas within a Vlasov-Maxwell description. The method used is fully relativistic and involves explicit integration of…

Astrophysics · Physics 2009-11-13 J Petri , J G Kirk

Particle-in-cell (PIC) simulations of relativistic shocks are in principle capable of predicting the spectra of photons that are radiated incoherently by the accelerated particles. The most direct method evaluates the spectrum using the…

High Energy Astrophysical Phenomena · Physics 2015-05-20 Brian Reville , John G. Kirk

This work introduces a new higher-order accurate super compact (HOSC) finite difference scheme for solving complex unsteady three-dimensional (3D) non-Newtonian fluid flow problems. As per the author's knowledge, the proposed scheme is the…

Fluid Dynamics · Physics 2024-07-30 Ashwani Punia , Rajendra K. Ray

The research is aimed at the study of the properties of solutions for parallel MHD shock waves in collisionless plasma with heat fluxes, using 8-moment MHD approximation. Restrictions have been established on the upstream shock parameters…

Plasma Physics · Physics 2020-03-24 V. D. Kuznetsov , A. I. Osin

We study a model describing the slow flow of a fluid through a deformable, porous, elastic solid undergoing small deformations. The stress-strain relationship of the solid incorporates nonlinear effects, formulated as a perturbation of the…

Numerical Analysis · Mathematics 2026-04-28 Andrea Bonito , Vivette Girault , Diane Guignard

Particle acceleration at magnetized purely perpendicular relativistic shocks in electron-ion plasmas are studied by means of two-dimensional particle-in-cell simulations. Magnetized shocks with the upstream bulk Lorentz factor $\gamma_1 \gg…

High Energy Astrophysical Phenomena · Physics 2022-01-20 Masanori Iwamoto , Takanobu Amano , Yosuke Matsumoto , Shuichi Matsukiyo , Masahiro Hoshino

Particle in Cell (PIC) simulations have become a vital tool for the investigation of kinetic processes in plasma physics. Many of the systems investigated with PIC simulations contain particles with relativistic velocities. The correct…

Plasma Physics · Physics 2026-03-09 Holger Schmitz

The probability that a particle, crossing the shock along a given direction, be reflected backwards along another direction, was shown to be the key element in determining the spectrum of non--thermal particles accelerated via the Fermi…

Astrophysics · Physics 2009-11-10 Pasquale Blasi , Mario Vietri