Non-inertial lateral migration of vesicles in bounded Poiseuille flow

TL;DR

This study investigates how vesicles migrate laterally in bounded Poiseuille flow without inertia, revealing a migration law influenced by walls and flow curvature, with results differing from unbounded cases.

Contribution

It introduces a new migration law for vesicles in bounded flow, accounting for wall effects and flow curvature, validated by experiments and simulations.

Findings

Vesicles migrate towards the channel center due to wall and curvature effects.

The migration law depends on structural parameters and flow conditions.

Migration velocity shows non-monotonous behavior with reduced volume beyond certain viscosity ratios.

Abstract

Cross-streamline non-inertial migration of a vesicle in a bounded Poiseuille flow is investigated experimentally and numerically. The combined effects of the walls and of the curvature of the velocity profile induce a movement towards the center of the channel. A migration law (as a function of relevant structural and flow parameters) is proposed that is consistent with experimental and numerical results. This similarity law markedly differs from its analogue in unbounded geometry. The dependency on the reduced volume $\nu$ and viscosity ratio $\lambda$ is also discussed. In particular, the migration velocity becomes non monotonous as a function of $\nu$ beyond a certain $\lambda$.