DSMC evaluation of the Navier-Stokes shear viscosity of a granular fluid

TL;DR

This paper introduces a DSMC-based method to measure the shear viscosity of granular fluids, demonstrating good agreement with theoretical predictions across various dissipation and density levels.

Contribution

It presents a novel simulation approach combining deterministic and stochastic forces to accurately evaluate shear viscosity in granular fluids.

Findings

System reaches hydrodynamic and Navier-Stokes regimes after transient

Method agrees well with Chapman-Enskog theoretical predictions

Effective across a wide range of dissipation and density values

Abstract

A method based on the simple shear flow modified by the introduction of a deterministic non-conservative force and a stochastic process is proposed to measure the Navier-Stokes shear viscosity in a granular fluid described by the Enskog equation. The method is implemented in DSMC simulations for a wide range of values of dissipation and density. It is observed that, after a certain transient period, the system reaches a hydrodynamic stage which tends to the Navier-Stokes regime for long times. The results are compared with theoretical predictions obtained from the Chapman-Enskog method in the leading Sonine approximation, showing quite a good agreement, even for strong dissipation.