Interfacial-dominated torque response in liquid-liquid Taylor-Couette flows

Naoki Hori*, Chong Shen Ng, Detlef Lohse, Roberto Verzicco

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

1 Citation (Scopus)
18 Downloads (Pure)

Abstract

Immiscible and incompressible liquid-liquid flows are considered in a Taylor-Couette geometry and analysed by direct numerical simulations coupled with the volume-of-fluid method and a continuum surface force model. The system Reynolds number is fixed to, where the single-phase flow is in the steady Taylor vortex regime, whereas the secondary-phase volume fraction and the system Weber number are varied to study the interactions between the interface and the Taylor vortices. We show that different Weber numbers lead to two distinctive flow regimes, namely an advection-dominated regime and an interface-dominated regime. When is high, the interface is easily deformed because of its low surface tension. The flow patterns are then similar to the single-phase flow, and the system is dominated mainly by advection (advection-dominated regime). However, when is low, the surface tension is so large that stable interfacial structures with sizes comparable to the cylinder gap can exist. The background velocity field is modulated largely by these persistent structures, thus the overall flow dynamics is governed by the interface (interface-dominated regime). The effect of the interface on the global system response is assessed by evaluating the Nusselt number based on the non-dimensional angular velocity transport. It shows non-monotonic trends as functions of the volume fraction for both low and high. We explain how these dependencies are closely linked to the velocity and interfacial structures.

Original languageEnglish
Article numberA15
JournalJournal of fluid mechanics
Volume956
Early online date1 Feb 2023
DOIs
Publication statusPublished - 10 Feb 2023

Keywords

  • interfacial flows (free surface)
  • Taylor-Couette flow
  • UT-Hybrid-D

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