Controlling secondary flow in Taylor-Couette turbulence through spanwise-varying roughness

Dennis Bakhuis, Rodrigo Ezeta, Pieter Berghout, Pim A. Bullee, Dominic Tai, Daniel Chung, Roberto Verzicco, Detlef Lohse, Sander G. Huisman, Chao Sun*

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

20 Downloads (Pure)

Abstract

Highly turbulent Taylor–Couette flow with spanwise-varying roughness is investigated experimentally and numerically (direct numerical simulations with an immersed boundary method) to determine the effects of the spacing and spanwise width s of the spanwise-varying roughness on the total drag and on the flow structures. We apply sandgrain roughness, in the form of alternating rough and smooth bands to the inner cylinder. Numerically, the Taylor number is O(109
) and the roughness width is varied in the range 0.47 6 s˜ = s/d 6 1.23, where d is the gap width.
Experimentally, we explore Ta = O(1012) and 0.61 6 s˜ 6 3.74. For both approaches the radius ratio is fixed at η = ri/ro = 0.716, with ri and ro the radius of the inner and outer cylinder respectively. We present how the global transport properties and the local flow structures depend on the boundary conditions set by the roughness spacing s˜. Both numerically and experimentally, we find a maximum in the angular momentum transport as a function of s˜. This can be attributed to the re-arrangement of the large-scale structures triggered by the presence of the rough stripes, leading to correspondingly large-scale turbulent vortices.
Original languageEnglish
Article numberA15
Number of pages23
JournalJournal of fluid mechanics
Volume883
DOIs
Publication statusPublished - 25 Jan 2020

Keywords

  • rotating turbulence
  • turbulent boundary layers
  • Taylor-Couette flow

Cite this