An oscillating motion of a red blood cell and a neutrally buoyant particle in Poiseuille flow in a narrow channel

TL;DR

This study investigates the oscillating motion of a neutrally buoyant particle in narrow channel Poiseuille flow, revealing how particle interactions with flow influence oscillation damping and cell inclination stability.

Contribution

It introduces a simplified model of red blood cell oscillations using a neutrally buoyant particle, highlighting the role of particle-flow interactions in oscillation behavior.

Findings

Particle's oscillation depends on its interaction with flow and position in the channel.

Oscillations damp out as the particle's center of mass stabilizes in the channel.

Inclination angle approaches a fixed value when oscillations diminish.

Abstract

Two motions of oscillation and vacillating breathing (swing) of a red blood cell have been observed in bounded Poiseuille flows (Phys. Rev. E 85, 16307 (2012)). To understand such motions, we have studied the oscillating motion of a neutrally buoyant rigid particle of the same shape in Poiseuille flow in a narrow channel and obtained that the crucial point is to have the particle interacting with Poiseuille flow with its mass center moving up and down in the channel central region. Since the mass center of the cell migrates toward the channel central region, its oscillating motion of the inclination angle is similar to the aforementioned motion as long as the cell keeps the shape of long body. But as the up-and-down oscillation of the cell mass center damps out, the oscillating motion of the inclination angle also damps out and the cell inclination angle approaches to a fixed angle.