Hydrodynamic interaction of a bubble pair in viscoelastic shear-thinning fluids

TL;DR

This study experimentally explores how bubble pairs interact in viscoelastic shear-thinning fluids, revealing unique behaviors like the drafting-kissing-dancing phenomenon influenced by fluid elasticity and bubble deformability.

Contribution

It introduces the drafting-kissing-dancing behavior in bubble interactions within viscoelastic shear-thinning fluids and links this to flow field characteristics and fluid properties.

Findings

Bubble pairs exhibit drafting-kissing-dancing behavior, unlike Newtonian fluids.

Flow fields show elasticity and negative wake effects influence bubble dynamics.

Bubble deformability affects the interaction pattern and clustering tendency.

Abstract

We experimentally investigate the interaction between a pair of bubbles ascending in a stagnant viscoelastic shear-thinning fluid. In particular, we focus on the effect of bubble size, across the velocity discontinuity, on the bubble-bubble interaction. Compared to the drafting-kissing-tumbling (DKT) behavior in Newtonian fluid, bubbles in the viscoelastic shear-thinning fluid exhibit, what we call, drafting-kissing-dancing (DKD) phenomenon. In the dancing phase, the bubble pair repeatedly interchange their relative leading and trailing positions as they rise to the free surface. To gain further insights, the flow fields around the bubble pair interaction are obtained using particle image velocimetry (PIV). From the experimental results, we suggest that the elasticity, deformability, and negative wake are responsible for such an interaction between the bubble pair, thus revealing the fundamental physics of bubble clustering often observed in non-Newtonian fluids.