Anomalous effect of turning off long-range mobility interactions in Stokesian Dynamics

TL;DR

This paper investigates the impact of neglecting long-range mobility interactions in Stokesian Dynamics simulations, revealing that such simplifications can lead to unphysical results in certain suspension types and proposing a mitigation strategy.

Contribution

It highlights the limitations of ignoring long-range interactions in specific suspension conditions and suggests a method to improve simulation accuracy.

Findings

Neglecting long-range interactions can cause unphysical results in bidisperse suspensions under external forces.

The approximation is acceptable in shear-driven, periodic suspensions.

Careful selection of particle pairs for lubrication interactions can mitigate issues.

Abstract

In Stokesian Dynamics, particles are assumed to interact in two ways: through long-range mobility interactions and through short-range lubrication interactions. To speed up computations, in shear-driven concentrated suspensions, often found in rheometric contexts, it is common to consider only lubrication. We show that, although this approximation may provide acceptable results in shear-driven, periodic suspensions, for bidisperse suspensions where the particles are exposed to an external force, it can produce physically unreasonable results. We suggest that this problem could be mitigated by a careful choice of particle pairs on which lubrication interactions should be included.