Particle Shape Influences Settling and Sorting Behavior in Microfluidic Domains

TL;DR

This study introduces a numerical model to simulate how particle shape and density affect their settling and flow trajectories in fluids, revealing shape-dependent behaviors and implications for microfluidic particle sorting.

Contribution

A novel numerical simulation approach capturing the influence of particle shape and density on settling and flow behaviors in microfluidic environments.

Findings

Shape and density significantly affect particle trajectories.

Surrogate circular particles lead to velocity miscalculations.

Shape changes influence particle entrapment and separation.

Abstract

We present a new numerical model to simulate settling trajectories of discretized individual or a mixture of particles of different geometrical shapes in a quiescent fluid and their flow trajectories in a flowing fluid. Simulations unveiled diverse particle settling trajectories as a function of their geometrical shape and density. The effects of the surface concavity of a boomerang particle and aspect ratio of a rectangular particle on the periodicity and amplitude of oscillations in their settling trajectories were numerically captured. Use of surrogate circular particles for settling or flowing of a mixture of non-circular particles were shown to miscalculate particle velocities by a factor of 0.9-2.2 and inaccurately determine the particles' trajectories. In a microfluidic chamber with particles of different shapes and sizes, simulations showed that steady vortices do not necessarily always control particle entrapments, nor do larger particles get selectively and consistently entrapped in steady vortices. Strikingly, a change in the shape of large particles from circular to elliptical resulted in stronger entrapments of smaller circular particles, but enhanced outflows of larger particles, which could be an alternative microfluidics-based method for sorting and separation of particles of different sizes and shapes.