How turbulence increases the bubble-particle collision rate

TL;DR

This study investigates how turbulence influences bubble-particle collision rates, revealing flow interactions and velocity fluctuations significantly enhance collisions, and introduces a model to predict these effects.

Contribution

It provides the first detailed simulation-based analysis of turbulence effects on bubble-particle collisions and proposes a new frozen-turbulence model for accurate predictions.

Findings

Turbulence can increase collision rates by up to 100% compared to still flow.

Flow interactions around bubbles are the dominant factor in collision enhancement.

Velocity fluctuations during interactions further boost collision rates.

Abstract

We study the effect of turbulence on collisions between a finite-size bubble and small inertial particles based on interface-resolved simulations. Our results show that the interaction with the flow field around the bubble remains the dominant effect. Nonlinear dependencies in this process can enhance the turbulent collision rate by up to 100\% compared to quiescent flow. Fluctuations in the bubble slip velocity during the interaction with the particle additionally increase the collision rate. We present a frozen-turbulence model that captures the relevant effects providing a physically consistent framework to model collisions of small inertial particles with finite-sized objects in turbulence.