Experimental and numerical investigation of bubble migration in shear flow: deformability-driven chaining and repulsion

TL;DR

This study combines experiments and simulations to explore how bubble deformability influences their migration and chaining behavior in shear flows, revealing that deformation-driven pressure interactions govern bubble interactions across different fluid rheologies.

Contribution

It demonstrates that bubble deformation significantly affects their migration and interactions in shear flow, unifying behavior across Newtonian, viscoelastic, and elastoviscoplastic fluids.

Findings

Bubbles form chains aligned with flow in elastoviscoplastic emulsions.

Interaction type depends on relative bubble positions, with attraction or repulsion.

Deformation-driven pressure interactions are key to bubble migration.

Abstract

We study the interaction-induced migration of bubbles in shear flow and observe that bubbles suspended in elastoviscoplastic emulsions organise into chains aligned in the flow direction, similarly to particles in viscoelastic fluids. To investigate the driving mechanism, we perform experiments and simulations on bubble pairs, using suspending fluids with different rheological properties. First, we notice that, for all fluids, the interaction type depends on the relative position of the bubbles. If they are aligned in the vorticity direction, they repel, if not, they attract each other. The simulations show a similar behavior in Newtonian fluids as in viscoelastic and elastoviscoplastic fluids, as long as the capillary number is sufficiently large. This shows that the interaction-related migration of the bubbles is strongly affected by the bubble deformation. We suggest that the cause of migration is the interaction between the heterogeneous pressure fields around the deformed bubbles, due to capillary pressure.