Lateral Migration and Nonuniform Rotation of Biconcave Particle Suspended in Poiseuille Flow

TL;DR

This study uses lattice Boltzmann simulations to explore the lateral migration, equilibrium positions, and nonuniform rotation of biconcave particles in Poiseuille flow, revealing unique behaviors influenced by flow conditions and particle shape.

Contribution

It provides new insights into the dynamics of biconcave particles, including multiple equilibrium positions and nonuniform rotation, under varying flow conditions using advanced numerical methods.

Findings

Two lateral equilibrium positions observed, with one decreasing as Reynolds number increases.

Nonuniform rotation causes regular wave patterns in lateral movement.

Flow field contours illustrate particle-posture interactions in rotation cycles.

Abstract

A biconcave particle suspended in a Poiseuille flow is investigated by the multiple-relaxation-time lattice Boltzmann method with the Galilean-invariant momentum exchange method. The lateral migration and equilibrium of the particle are similar to the Segr\'e-Silberberg effect in our numerical simulations. Surprisingly, two lateral equilibrium positions are observed corresponding to the releasing positions of the biconcave particle. The upper equilibrium positions significantly decrease with the growth of the Reynolds number, whereas the lower ones are almost insensitive to the Reynolds number. Interestingly, the regular wave accompanied by nonuniform rotation is exhibited in the lateral movement of the biconcave particle. It can be attributed to that the biconcave shape in various postures interacts with the parabolic velocity distribution of the Poiseuille flow. A set of contours illustrate the dynamic flow field when the biconcave particle has successive postures in a rotating period.