The effect of curvature and topology on membrane hydrodynamics

TL;DR

This paper investigates how the curvature and topology of a spherical liquid-liquid interface influence the mobility of embedded rods, combining theoretical models with experiments to reveal effects not seen in flat interfaces.

Contribution

It provides new theoretical and experimental insights into how curvature and topology alter membrane hydrodynamics and object mobility.

Findings

Curvature and topology significantly modify object mobility on interfaces.

Viscosity mismatch suppresses fluid flow on small droplets.

Experimental results confirm theoretical predictions.

Abstract

We study the mobility of extended objects (rods) on a spherical liquid-liquid interface to show how this quantity is modified in a striking manner by both the curvature and the topology of the interface. We present theoretical calculations and experimental measurements of the interfacial fluid velocity field around a moving rod bound to the crowded interface of a water-in-oil droplet. By using different droplet sizes, membrane viscosities, and rod lengths, we show that the viscosity mismatch between the interior and exterior fluids leads to a suppression of the fluid flow on small droplets that cannot be captured by the flat interface predictions.