Electrohydrodynamics of deflated vesicles: budding, rheology and pairwise interactions

TL;DR

This study investigates the electrohydrodynamics of vesicle suspensions under DC electric fields, revealing nonlinear rheological behavior, vesicle shape transitions, and diverse pairwise interaction responses such as chain formation, rotation, and oscillation.

Contribution

It provides new insights into vesicle pair interactions and rheology in electric fields, especially for smaller reduced areas, extending previous experimental and numerical findings.

Findings

Suspension rheology varies nonlinearly with conductivity ratio.

Vesicle shape transitions depend on reduced area.

Three interaction responses observed: chain formation, rotation, oscillation.

Abstract

The electrohydrodynamics of vesicle suspensions is characterized by studying their pairwise interactions in applied DC electric fields in two dimensions. In the dilute limit, the rheology of the suspension is shown to vary nonlinearly with the electric conductivity ratio of the interior and exterior fluids. The prolate-oblate-prolate transition and other transitionary dynamics observed in experiments and previously confirmed via numerical simulations is further investigated here for smaller reduced areas. When two vesicles are initially un-aligned with the external electric field, three different responses are observed when the key parameters are varied: (i) chain formation--they self-assemble to form a chain that is aligned along the field direction, (ii) circulatory motion--they rotate about each other, (iii) oscillatory motion--they form a chain but oscillate about each other.