Shear-induced self-diffusivity in dilute suspensions with repulsive interactions

Fuente: arXiv
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Main Authors: Nath, Anu V S, Patra, Pijush, Roy, Anubhab
Format: Preprint
Published: 2026
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author Nath, Anu V S
Patra, Pijush
Roy, Anubhab
author_facet Nath, Anu V S
Patra, Pijush
Roy, Anubhab
contents In a dilute non-Brownian suspension undergoing simple shear, pairwise hydrodynamic interactions are fore-aft symmetric at zero Reynolds number and produce no net cross-streamline displacement. A weak central repulsive force between particles breaks this symmetry, deflecting trajectories and generating irreversible transverse displacements that cumulatively yield a shear-induced self-diffusivity. We derive, via matched asymptotic expansions in the limit of weak repulsion, closed-form scaling laws for the gradient and vorticity components of this diffusivity. The gradient component exhibits a logarithmic enhancement relative to the vorticity component, a structural anisotropy that persists for all monotonically decaying repulsive potentials. The specific interaction enters only through integral functionals of the force profile weighted by hydrodynamic mobility functions, establishing that the scaling is universal across physically distinct mechanisms, such as electrical double-layer repulsion, steric interactions, or any other short-range central force. We validate the asymptotic predictions against full numerical trajectory integration for the representative case of electrostatic repulsion, modelled using the Gouy-Chapman description of the electrical double layer, and find excellent agreement in the expected regime.
format Preprint
id arxiv_https___arxiv_org_abs_2603_27396
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Shear-induced self-diffusivity in dilute suspensions with repulsive interactions
Nath, Anu V S
Patra, Pijush
Roy, Anubhab
Soft Condensed Matter
Fluid Dynamics
In a dilute non-Brownian suspension undergoing simple shear, pairwise hydrodynamic interactions are fore-aft symmetric at zero Reynolds number and produce no net cross-streamline displacement. A weak central repulsive force between particles breaks this symmetry, deflecting trajectories and generating irreversible transverse displacements that cumulatively yield a shear-induced self-diffusivity. We derive, via matched asymptotic expansions in the limit of weak repulsion, closed-form scaling laws for the gradient and vorticity components of this diffusivity. The gradient component exhibits a logarithmic enhancement relative to the vorticity component, a structural anisotropy that persists for all monotonically decaying repulsive potentials. The specific interaction enters only through integral functionals of the force profile weighted by hydrodynamic mobility functions, establishing that the scaling is universal across physically distinct mechanisms, such as electrical double-layer repulsion, steric interactions, or any other short-range central force. We validate the asymptotic predictions against full numerical trajectory integration for the representative case of electrostatic repulsion, modelled using the Gouy-Chapman description of the electrical double layer, and find excellent agreement in the expected regime.
title Shear-induced self-diffusivity in dilute suspensions with repulsive interactions
topic Soft Condensed Matter
Fluid Dynamics
url https://arxiv.org/abs/2603.27396