Hydrodynamic interaction between coaxially rising bubbles in elastoviscoplastic materials: Equal bubbles

Abstract

We investigate the pair interaction of equal-size, tandem bubbles rising in yield stress fluids with elasticity. This configuration manifests intense attractive dynamics and conforms with experimental reports that, in such materials, a bubble tends to follow the path of a preceding one. We demonstrate that the reason is that the solid-like behavior of the material preserves stresses generated by the passage of the leading bubble and makes the material ``softer'' for the trailing one. We conduct an extensive parametric study, on the geometric features such as the bubble radius and the initial separation distance, and on the material properties.