Deformable ellipsoidal bubbles in Taylor-Couette flow with enhanced Euler-Lagrangian tracking

Vamsi Spandan, Roberto Verzicco, and Detlef Lohse
Phys. Rev. Fluids 2, 104304 – Published 16 October 2017

Abstract

In this work we present numerical simulations of 105 sub-Kolmogorov deformable bubbles dispersed in Taylor-Couette flow (a wall-bounded shear system) with rotating inner cylinder and outer cylinder at rest. We study the effect of deformability of the bubbles on the overall drag induced by the carrier fluid in the two-phase system. We find that an increase in deformability of the bubbles results in enhanced drag reduction due to a more pronounced accumulation of the deformed bubbles near the driving inner wall. This preferential accumulation is induced by an increase in the resistance to the motion of the bubbles in the wall-normal direction. The increased resistance is linked to the strong deformation of the bubbles near the wall which makes them prolate (stretched along one axis) and orient along the streamwise direction. A larger concentration of the bubbles near the driving wall implies that they are more effective in weakening the plume ejections which results in stronger drag reduction effects. These simulations which are practically impossible with fully resolved techniques are made possible by coupling a subgrid deformation model with two-way coupled Euler-Lagrangian tracking of sub-Kolmogorov bubbles dispersed in a turbulent flow field which is solved through direct numerical simulations. The bubbles are considered to be ellipsoidal in shape and their deformation is governed by an evolution equation which depends on the local flow conditions and their surface tension.

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  • Received 24 March 2017

DOI:https://doi.org/10.1103/PhysRevFluids.2.104304

©2017 American Physical Society

Physics Subject Headings (PhySH)

Fluid Dynamics

Authors & Affiliations

Vamsi Spandan1, Roberto Verzicco1,2, and Detlef Lohse1,3

  • 1Physics of Fluids and Max Planck-University of Twente Center for Complex Fluid Dynamics, University of Twente, P.O. Box 217, 7500 AE Enschede, Netherlands
  • 2Dipartimento di Ingegneria Meccanica, University of Rome Tor Vergata, Via del Politecnico 1, Rome 00133, Italy
  • 3Max Planck Institute for Dynamics and Self-Organization, 37077 Göttingen, Germany

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Vol. 2, Iss. 10 — October 2017

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