Clustering of passive impurities in MHD turbulence

TL;DR

This study uses high-resolution simulations to analyze how passive impurities, both neutral and charged, cluster in incompressible MHD turbulence, revealing complex spatial distributions influenced by flow structures and particle charge.

Contribution

It provides new insights into the clustering behavior of passive impurities in MHD turbulence, highlighting the effects of particle charge and flow structures on their spatial distribution.

Findings

Neutral particles cluster near vortex sheets due to viscous drag.

Charged particles exhibit different clustering patterns influenced by Lorentz forces.

Charge magnitude affects the degree of clustering, with small charges increasing and larger charges decreasing clustering.

Abstract

The transport of heavy, neutral or charged, point-like particles by incompressible, resistive magnetohydrodynamic (MHD) turbulence is investigated by means of high-resolution numerical simulations. The spatial distribution of such impurities is observed to display strong deviations from homogeneity, both at dissipative and inertial range scales. Neutral particles tend to cluster in the vicinity of coherent vortex sheets due to their viscous drag with the flow, leading to the simultaneous presence of very concentrated and almost empty regions. The signature of clustering is different for charged particles. These exhibit in addition to the drag the Lorentz-force. The regions of spatial inhomogeneities change due to attractive and repulsive vortex sheets. While small charges increase clustering, larger charges have a reverse effect.