Swinging and Tumbling of Fluid Vesicles in Shear Flow

TL;DR

This paper investigates the complex dynamics of fluid vesicles in shear flow, revealing a new swinging state and providing a phase diagram that aligns with experimental observations.

Contribution

It introduces a theoretical model predicting a new swinging state in vesicle dynamics and maps the phase diagram based on physical parameters.

Findings

Identification of a new swinging state between tank-treading and tumbling

Prediction of the phase diagram as a function of shear rate and viscosities

Good agreement with recent experimental results

Abstract

The dynamics of fluid vesicles in simple shear flow is studied using mesoscale simulations of dynamically-triangulated surfaces, as well as a theoretical approach based on two variables, a shape parameter and the inclination angle, which has no adjustable parameters. We show that between the well-known tank-treading and tumbling states, a new ``swinging'' state can appear. We predict the dynamic phase diagram as a function of the shear rate, the viscosities of the membrane and the internal fluid, and the reduced vesicle volume. Our results agree well with recent experiments.