Path instability of a no-slip spheroidal bubble in isotropic turbulence

Gihun Shim, Jongsu Kim, Changhoon Lee

Research output: Contribution to journalArticlepeer-review

5 Citations (Scopus)

Abstract

Path instability of a millimetric spheroidal bubble in quiescent fluid and in isotropic turbulence is investigated by direct numerical simulation. An immersed boundary method along with a new formulation of the equation of bubble motion is utilized to impose the no-slip condition on the surface of an air bubble in fixed shape with the equivalent diameter of in contaminated water. The range of Galilei number defined as the ratio of the gravitational force to the kinematic viscosity considered in this study is 100 800. In still fluid, as the bubble size grows, the frequency of the zigzagging motion of the bubble increases while the range in the orientation angle variation of the bubble is hardly affected. The effect of background turbulence on path instability of a rising bubble, which typically shows zigzag pattern in still fluid, is investigated at three different Reynolds numbers, , of 26, 45, and 73, or equivalently, for the ratio of fluid root-mean-square velocity to the bubble rise velocity ranging 0.030 0.671. When a bubble rises in isotropic turbulence, the terminal rise velocity of the bubble does not show a noticeable difference. However, the pathways are significantly distorted by turbulence. Furthermore, the magnitude of zigzagging frequency and the degree of obliquity of the bubble become enhanced with . We also observed wakes behind the bubble to find that the rear tails become weaker and tangled due to turbulence.

Original languageEnglish
Article number073603
JournalPhysical Review Fluids
Volume6
Issue number7
DOIs
Publication statusPublished - 2021 Jul

Bibliographical note

Publisher Copyright:
©2021 American Physical Society

All Science Journal Classification (ASJC) codes

  • Computational Mechanics
  • Modelling and Simulation
  • Fluid Flow and Transfer Processes

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