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

Vamsi Spandan Arza, Roberto Verzicco, Detlef Lohse

Research output: Contribution to journalArticleAcademicpeer-review

5 Citations (Scopus)
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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.

Original languageEnglish
Article number104304
JournalPhysical review fluids
Volume2
Issue number10
DOIs
Publication statusPublished - 1 Oct 2017

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Taylor-Couette Flow
Bubble
Euler
Drag reduction
Formability
Phosmet
Shear walls
Direct numerical simulation
Turbulent flow
Drag
Surface tension
Drag Reduction
Flow fields
Fluids
Computer simulation
Surface Tension
Turbulent Flow
Flow Field
Evolution Equation
Direction compound

Cite this

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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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Deformable ellipsoidal bubbles in Taylor-Couette flow with enhanced Euler-Lagrangian tracking. / Arza, Vamsi Spandan; Verzicco, Roberto; Lohse, Detlef.

In: Physical review fluids, Vol. 2, No. 10, 104304, 01.10.2017.

Research output: Contribution to journalArticleAcademicpeer-review

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