In the Universe, matter outside of stars and compact objects is mostly composed collisionless plasma. The interaction a supersonic plasma flow with an obstacle results in shocks that are often associated intense nonthermal radiation production cosmic ray particles. Motivated by simulations non-relativistic high-Mach-number supernova remnants, we investigate instabilities excited relativistic el...

We present predictions for the statistical error due to finite sampling in the presence of thermal fluctuations in molecular simulation algorithms. Expressions for the fluid velocity, density and temperature are derived using equilibrium statistical mechanics. The results show that the number of samples needed to adequately resolve the flowfield scales as the inverse square of the Mach number. ...

We present a new approach to Eulerian computational fluid dynamics that is designed to work at high Mach numbers encountered in astrophysical hydrodynamic simulations. The Eulerian fluid conservation equations are solved in an adaptive frame moving with the fluid where Mach numbers are minimized. The moving frame approach uses a velocity decomposition technique to define local kinetic variables...

In this survey paper, we are concerned with the zero Mach number limit for compressible viscous flows. For the sake of (mathematical) simplicity, we restrict ourselves to the case of barotropic fluids and we assume that the flow evolves in the whole space or satisfies periodic boundary conditions. We focus on the case of ill-prepared data. Hence highly oscillating acoustic waves are likely to p...

Large-scale particle-in-cell calculations of the plasma wake interactions of two negatively charged grains smaller than the Debye length are carried out using the coptic code over a wide range of subsonic plasma flow velocities. In plasmas with the temperature ratio T(e)/T(i)=100, it is found that a single grain's oscillatory wake disappears for flow Mach numbers M less than approximately 0.3, ...

Through a linear analysis, we show how to modify Godunov type schemes applied to the compressible Euler system to make them accurate at any Mach number. This allows to propose all Mach Godunov type schemes. A linear stability result is proposed and a formal asymptotic analysis justifies the construction in the barotropic case when the Godunov type scheme is a Roe scheme. We also underline that ...

Electron acceleration in collisionless shocks with arbitrary magnetic field orientations is discussed. It is shown that the injection of thermal electrons into the diffusive shock acceleration process is achieved by an electron beam with a loss cone in velocity space that is reflected back upstream from the shock through the shock drift acceleration mechanism. The electron beam is able to excit...

A new formulation for the numerical solution of low Mach number compressible flow problems is presented and analyzed. In this formulation the thermal part (energy and species equations) is solved implicitly and decoupled from the momentum equation, whereas the hydrodynamic part (momentumcontinuity) is advanced in time using a high order splitting approach which results in overall high order acc...