The turbulent destruction of clouds - III. Three dimensional adiabatic shock-cloud simulations

TL;DR

This paper presents 3D hydrodynamic simulations of shock-cloud interactions, comparing effects of Mach number and density contrast, and evaluates resolution requirements and differences from 2D models, with implications for cloud destruction and mixing.

Contribution

It provides detailed 3D simulation results of shock-cloud interactions, including turbulence modeling and resolution tests, highlighting similarities and differences with 2D simulations.

Findings

3D simulations require 32-64 cells per cloud radius for key dynamics

Inviscid and turbulence model results agree well in 3D

Cloud lifetime and acceleration are similar in 2D and 3D simulations

Abstract

We present 3D hydrodynamic simulations of the adiabatic interaction of a shock with a dense, spherical cloud. We compare how the nature of the interaction changes with the Mach number of the shock, $M$, and the density contrast of the cloud, $\chi$. We examine the differences with 2D axisymmetric calculations, perform detailed resolution tests, and compare "inviscid" results to those obtained with the inclusion of a $k$-$\epsilon$ subgrid turbulence model. Resolutions of 32-64 cells per cloud radius are the minimum necessary to capture the dominant dynamical processes in 3D simulations, while the 3D inviscid and $k$-$\epsilon$ simulations typically show very good agreement. Clouds accelerate and mix up to 5 times faster when they are poorly resolved. The interaction proceeds very similarly in 2D and 3D - although non-azimuthal modes lead to different behaviour, there is very little effect on key global quantities such as the lifetime of the cloud and its acceleration. In particular, we do not find significant differences in the hollowing or "voiding" of the cloud between 2D and 3D simulations with $M=10$ and $\chi=10$, which contradicts previous work in the literature.