A numerical study of the motion of a neutrally buoyant cylinder in two dimensional shear flow

TL;DR

This study uses direct numerical simulation to analyze the complex motion of neutrally buoyant cylinders in two-dimensional shear flow, revealing equilibrium positions and migration behaviors influenced by flow forces.

Contribution

It provides a detailed numerical analysis of neutrally buoyant cylinders' motion in shear flow, including validation against existing results and insights into migration mechanisms.

Findings

Centerline is an equilibrium position for the cylinder.

Particles migrate to different equilibrium points at higher Reynolds numbers.

The study confirms a power law relating angular speed and Reynolds number.

Abstract

In this paper, we investigate the motion of a neutrally buoyant cylinder of circular or elliptic shape in two dimensional shear flow of a Newtonian fluid by direct numerical simulation. The numerical results are validated by comparisons with existing theoretical, experimental and numerical results, including a power law of the normalized angular speed versus the particle Reynolds number. The centerline between two walls is an expected equilibrium position of the cylinder mass center in shear flow. When placing the particle away from the centerline initially, it migrates toward another equilibrium position for higher Reynolds numbers due to the interplay between the slip velocity, the Magnus force, and the wall repulsion force.