The lift force on deformable and freely moving bubbles in linear shear flows
Journal article, 2022

This paper provides a comprehensive explanation for the lift force acting on a freely deformable bubble rising in a linear shear flow and examines how the lift force scales with the undisturbed shear rate in cases governed by different lift force mechanisms. Four distinct flow mechanisms are identified from previous studies, and the associated bubble-induced vorticity dynamics are outlined. We provide a theoretical framework to qualitatively explain the lift force acting on a bubble in terms of moments of the bubble-induced vorticity. We support our theoretical framework with three-dimensional multiphase direct numerical simulations to illustrate how the vorticity dynamics associated with the four mechanisms generate the lift force. These findings provide a comprehensive explanation for the behaviour of the lift force in a wide range of relevant governing parameters. Additionally, our simulation results show how differently the lift force scales with the shear rate, depending on the dominating lift force mechanism. These results indicate that the shear rate should, in general, be accounted for in highly viscous flows (low Galilei numbers) or at significant bubble deformations (moderate-to-high Eötvös numbers) when modelling the lift force coefficient.

bubbles

shear flow

lift force

vorticity dynamics

moving reference frame

DNS

Author

Niklas Hidman

Chalmers, Mechanics and Maritime Sciences (M2), Fluid Dynamics

Henrik Ström

Chalmers, Mechanics and Maritime Sciences (M2), Fluid Dynamics

Srdjan Sasic

Chalmers, Mechanics and Maritime Sciences (M2), Fluid Dynamics

Gaetano Sardina

Chalmers, Mechanics and Maritime Sciences (M2), Fluid Dynamics

Journal of Fluid Mechanics

0022-1120 (ISSN) 1469-7645 (eISSN)

Vol. 952 A34

Understanding and modelling bubble-induced turbulence

Swedish Research Council (VR) (2017-05031), 2018-01-01 -- 2021-12-31.

Areas of Advance

Production

Energy

Roots

Basic sciences

Infrastructure

C3SE (Chalmers Centre for Computational Science and Engineering)

Subject Categories

Fluid Mechanics and Acoustics

DOI

10.1017/jfm.2022.917

More information

Latest update

10/26/2023