Falling Particles in Fluids at Intermediate Reynolds Numbers

TL;DR

This paper investigates the complex dynamics and configurations of multiple particles falling in a fluid at intermediate Reynolds numbers, revealing how initial arrangements influence steady states and clustering behavior.

Contribution

It provides new insights into how particle number parity and initial spacing affect the steady configurations and clustering of falling particles at Re=200.

Findings

Convex shape for 3 particles, concave for 4 in steady state.

Mixed shapes for larger odd numbers of particles.

Clustering of particles occurs below a certain initial spacing.

Abstract

In this video, we present the dynamics of an array of falling particles at intermediate Reynolds numbers. The film shows the vorticity plots of 3, 4, 7, 16 falling particles at $Re = 200$. We highlight the effect of parity on the falling configuration of the array. In steady state, an initially uniformly spaced array forms a convex shape when $n=3$, i.e the middle particle leads, but forms a concave shape when $n = 4$. For larger odd numbers of particles, the final state consists of a mixture of concave and convex shapes. For larger even numbers of particles, the steady state remains a concave shape. Below a threshold of initial particle spacing, particles cluster in groups of 2 to 3.