Direct Simulation Monte Carlo for astrophysical flows: I. Motivation and methodology release_jh5ybqlorzdydexw547odij3ty

by Martin D. Weinberg

Released as a article .

2013  

Abstract

We describe a hybrid Direct Simulation Monte Carlo (DSMC) code for simultaneously solving the collisional Boltzmann equation for gas and the collisionless Boltzmann equation for stars and dark matter for problems important to galaxy evolution. This project is motivated by the need to understand the controlling dynamics at interfaces between gases of widely differing densities and temperature, i.e. multiphase media. While more expensive than hydrodynamics, the kinetic approach does not suffer from discontinuities and it applies when the continuum limit does not, such as in the collapse of galaxy clusters and at the interface between coronal halo gas and a thin neutral gas layer. Finally, the momentum flux is carried, self-consistently, by particles and this approach explicitly resolves and thereby captures shocks. The DSMC method splits the solution into two pieces: 1) the evolution of the phase-space flow without collisions; and 2) the evolution governed the collision term alone without phase-space flow. This splitting approach makes DSMC an ideal match to existing particle-based n-body codes. If the mean free path becomes very small compared to any scale of interest, the method abandons simulated particle collisions and simply adopts the relaxed solution in each interaction cell consistent with the overall energy and momentum fluxes. This is functionally equivalent to solving the Navier-Stokes equations on a mesh. Our implementation is tested using the Sod shock tube problem and the non-linear development of an Kelvin-Helmholtz unstable shear layer.
In text/plain format

Archived Files and Locations

application/pdf  394.9 kB
file_vzjg3jtlcrgavgsxpuuqwhjnn4
archive.org (archive)
Read Archived PDF
Preserved and Accessible
Type  article
Stage   submitted
Date   2013-04-14
Version   v1
Language   en ?
arXiv  1304.3941v1
Work Entity
access all versions, variants, and formats of this works (eg, pre-prints)
Catalog Record
Revision: d5a48879-64df-4780-9384-6f174df48615
API URL: JSON