Lift and down-gradient shear-induced diffusion in Red Blood Cell suspensions

TL;DR

This paper investigates the behavior of Red Blood Cells in shear flow, revealing significant lift velocities and anisotropic shear-induced diffusion, including a generic down-gradient subdiffusion with an exponent of 1/3.

Contribution

It provides new measurements of RBC lift velocities and shear-induced diffusion, highlighting anisotropic and subdiffusive behaviors in confined flows.

Findings

RBCs exhibit significant lift velocities despite tumbling motion.

Shear-induced diffusion is anisotropic and characterized by a subdiffusive exponent of 1/3.

Distribution of RBCs shows depletion near walls due to competing migration and diffusion.

Abstract

The distribution of Red Blood Cells in a confined channel flow is inhomogeneous and shows a marked depletion near the walls due to a competition between migration away from the walls and shear-induced diffusion resulting from interactions between particles. We investigated the lift of RBCs in a shear flow near a wall and measured a significant lift velocity despite the tumbling motion of cells. We also provide values for the collective and anisotropic shear-induced diffusion of a cloud of RBCs, both in the direction of shear and in the direction of vorticity. A generic down-gradient subdiffusion characterized by an exponent 1/3 is highlighted.