Accelerated Inertial Regime in the Spinodal Decomposition of Magnetic Fluids

TL;DR

This study uses molecular dynamics simulations to demonstrate the presence of an inertial growth regime in the spinodal decomposition of a magnetic fluid, showing dominant fluid inertia from early times and confirming theoretical predictions.

Contribution

First MD simulation evidence of inertial scaling in magnetic fluids during spinodal decomposition, revealing dominance of inertia from the outset.

Findings

Inertial growth regime observed over extended time window

Fluid inertia dominates from the beginning, bypassing diffusive and viscous regimes

Magnetic dipolar interactions influence phase separation dynamics

Abstract

Furukawa predicted that at late times, the domain growth in binary fluids scales as $\ell(t)\sim t^{2/3}$, and the growth is driven by fluid inertia. The {\it inertial growth regime} has been highly elusive in molecular dynamics (MD) simulations. We perform coarsening studies of the Stockmayer (SM) model comprising of magnetic dipoles that interact via long-range dipolar interactions as well as the usual Lennard-Jones (LJ) potential. This fascinating polar fluid exhibits a gas-liquid phase coexistence, and magnetic order even in the absence of an external field. From comprehensive MD simulations, we observe the inertial scaling [$\ell(t)\sim t^{2/3}$] in the SM fluid for an extended time window. Intriguingly, the fluid inertia is overwhelming from the outset - our simulations do not show the early diffusive regime [$\ell(t)\sim t^{1/3}$] and the intermediate viscous regime [$\ell(t)\sim t$] prevalent in LJ fluids.