Characteristic spatial scale of vesicle pair interactions in a plane linear flow

TL;DR

This study experimentally investigates how vesicles in a plane linear flow interact at various distances, revealing a characteristic interaction scale up to about 3.2 to 3.7 times their radius, which influences suspension behavior.

Contribution

The paper introduces experimental measurements of vesicle interactions in a microfluidic flow, establishing a lower bound for the interaction scale and implications for suspension volume fractions.

Findings

Vesicle interactions extend up to 3.2-3.7 times their radius.

Single vesicle dynamics are significantly affected by nearby vesicles.

Provides bounds for non-interacting vesicle suspension volume fractions.

Abstract

We report the experimental studies on interaction of two vesicles trapped in a microfluidic analog of four-roll mill, where a plane linear flow is realized. We found that the dynamics of a single vesicle is significantly altered by the presence of another vesicle at separation distances up to about 3.2 \div 3.7 times of effective radius of the vesicles. This is supported by direct measurements of a single vesicle back-reaction on the velocity field. Thus, the experiment provides the lower bound for the interaction scale of vesicles and so the corresponding upper bound for the volume fraction \phi=0.08 \div 0.13 of non-interacting vesicle suspensions.