Inviscid SPH

TL;DR

This paper introduces a new method for controlling artificial viscosity in SPH simulations, effectively eliminating unwanted dissipation away from shocks while maintaining accuracy at shocks.

Contribution

A novel shock indicator based on the total derivative of velocity divergence that reduces artificial viscosity away from shocks in SPH.

Findings

Works as well as previous methods in strong-shock regimes

Virtually eliminates viscosity away from shocks

Preserves particle order and minimizes damping of sound waves

Abstract

In smooth-particle hydrodynamics (SPH), artificial viscosity is necessary for the correct treatment of shocks, but often generates unwanted dissipation away from shocks. We present a novel method of controlling the amount of artificial viscosity, which uses the total time derivative of the velocity divergence as shock indicator and aims at completely eliminating viscosity away from shocks. We subject the new scheme to numerous tests and find that the method works at least as well as any previous technique in the strong-shock regime, but becomes virtually inviscid away from shocks, while still maintaining particle order. In particular sound waves or oscillations of gas spheres are hardly damped over many periods.