Channel Foam Flow Around an Obstacle in a Two-Dimensional Bubble Model

TL;DR

This study uses a two-dimensional bubble model to numerically analyze foam flow around an obstacle, revealing how polydispersity, external force, and packing fraction influence flow regimes and yield behavior.

Contribution

It introduces a systematic numerical investigation of foam flow around an obstacle, identifying thresholds for plasticity crossover and yield drag phenomena.

Findings

Polydispersity threshold marks transition from crystalline-like to amorphous-like flow.

Existence of a critical external force for steady flow (yield drag).

Critical packing fraction determines the onset of yield-drag behavior.

Abstract

We numerically study confined channel foam flow around an obstacle using a two-dimensional bubble model, inspired by experiments performed in the same geometry. We systematically vary the polydispersity, the external driving force, and the packing fraction of the system. Our simulations capture a broad range of plastic flow phenomenologies, from highly directional, sliding-like motion characteristic of crystalline materials to more isotropic and localized rearrangements typical of amorphous systems. We identify a threshold value of polydispersity that marks the crossover between crystalline-like and amorphous-like plasticity. In addition, we observe the existence of a critical external force, associated with the phenomenon of yield drag, above which the system reaches steady flow and below which it remains arrested. We determine a critical packing fraction above which such yield-drag behavior emerges. Our results provide a comprehensive framework for understanding the interplay between disorder, driving, and the presence of an obstacle in foam flows.