Chemical mixing in smoothed particle hydrodynamics simulations

TL;DR

This paper presents a new efficient algorithm for modeling chemical mixing in smoothed particle hydrodynamics simulations, linking diffusivity to local conditions to accurately simulate element dispersal without resolving small-scale instabilities.

Contribution

The authors introduce a turbulence-based diffusion algorithm for SPH that models chemical mixing based on local velocity dispersion, applicable to various astrophysical scenarios.

Findings

Successfully models heavy element distribution in supernova remnants.

Does not require resolving hydrodynamic instabilities explicitly.

Applicable to galaxy and intergalactic medium simulations.

Abstract

We introduce a simple and efficient algorithm for diffusion in smoothed particle hydrodynamics (SPH) simulations and apply it to the problem of chemical mixing. Based on the concept of turbulent diffusion, we link the diffusivity of a pollutant to the local physical conditions and can thus resolve mixing in space and time. We apply our prescription to the evolution of an idealized supernova remnant and find that we can model the distribution of heavy elements without having to explicitly resolve hydrodynamic instabilities in the post-shock gas. Instead, the dispersal of the pollutant is implicitly modelled through its dependence on the local velocity dispersion. Our method can thus be used in any SPH simulation that investigates chemical mixing but lacks the necessary resolution on small scales. Potential applications include the enrichment of the interstellar medium in present-day galaxies, as well as the intergalactic medium at high redshifts.