MULTIGRAIN: Simulating mixtures of multiple dust grains and gas with SPH

TL;DR

MULTIGRAIN is an advanced SPH algorithm that accurately simulates multiple dust grain phases in gas, capturing backreaction effects and improving upon previous two-phase models for astrophysical disc studies.

Contribution

It introduces a novel, efficient multi-phase dust-gas simulation method that accounts for mutual backreaction and extends prior two-phase SPH models.

Findings

More accurate than single-phase models due to backreaction effects

Efficient explicit algorithm with low storage requirements

Applicable to astrophysical disc dust settling simulations

Abstract

We present MULTIGRAIN, an algorithm for simulating multiple phases of small dust grains embedded in a gas, building on our earlier work in simulating two-phase mixtures of gas and dust in SPH (Laibe & Price 2012a,b; Price & Laibe 2015). The MULTIGRAIN method (Hutchison, Price & Laibe 2018) is more accurate than single-phase simulations because the gas experiences a backreaction from each dust phase and communicates this change to the other phases, thereby indirectly coupling the dust phases together. The MULTIGRAIN method is fast, explicit and low storage, requiring only an array of dust fractions and their derivatives defined for each resolution element. We demonstrate the MULTIGRAIN algorithm on test problems related to the settling of dust in the discs of gas around young stars, where solar systems are born. Finally I will discuss possible extensions of the method to incorporate both large and small grains, together with recent improvements in our numerical techniques for gas and dust mixtures. In particular, I will show how the 'overdamping' problem identified by Laibe & Price (2012a) can be solved.