Squeezing multiple soft particles into a constriction: transition to clogging

TL;DR

This study uses advanced 3D simulations to analyze how deformable capsules pass through constrictions, revealing how capsule deformability influences clogging and passage in microfluidic environments.

Contribution

It introduces a comprehensive simulation framework combining lattice Boltzmann, immersed boundary, and finite element methods to study capsule flow and clogging.

Findings

Deformable capsules can pass through narrower constrictions than rigid ones.

Capsule deformability increases the likelihood of passage versus clogging.

The transition depends on capsule size, constriction width, and membrane elasticity.

Abstract

We study numerically how multiple deformable capsules squeeze into a constriction. This situation is largely encountered in microfluidic chips designed to manipulate living cells, which are soft entities. We use fully three-dimensional simulations based on the lattice Boltzmann method to compute the flow of the suspending fluid, and on the immersed boundary method to achieve the two-way fluid-structure interaction. The mechanics of the capsule membrane elasticity is computed with the finite element method. We obtain two main states: continuous passage of the particles, and their blockage that leads to clogging the constriction. The transition from one state to another is dictated by the ratio between the size of the capsules and the constriction width, and by the capsule membrane deformability. This latter is found to enhance particle passage through narrower constrictions, where rigid particles with similar diameter are blocked and lead to clogging.