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
Journal of Fluid Mechanics | Cambridge University Press (CUP) | Published : 2020
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 ss 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)O(109) and the roughness width is varied in the range 0.47⩽s~=s/d⩽1.230.47⩽s~=s/d⩽1.23 , where dd is the gap width. Experimentally, we explore Ta=O(1012)Ta=O(1012) and 0.61⩽s~⩽3.740.61⩽s~⩽3.74 . For both approaches the radius ratio is ..View full abstract
Awarded by Natural Science Foundation of China
Awarded by VIDI grant
Awarded by PRACE project
D.B., R.E. and P.B. contributed equally to this work. We would like to thank D. Krug for various stimulating discussions. We like to thank J. E. Escobar for performing the confocal microscopy measurements and G.-W. Bruggert for technical support. This work was funded by Natural Science Foundation of China under grant no. 91852202, VIDI grant no. 13477, STW, FOM, MCEC and the Netherlands Organisation for Scientific Research (NWO). This project is also partially funded by the Priority Programme SPP 1881 Turbulent Superstructures of the Deutsche Forschungsgemeinschaft. We also acknowledge PRACE for awarding us access to MareNostrum based in Spain at the Barcelona Supercomputing Center (BSC) under PRACE project no. 2017174146. This work was partly carried out on the national e-infrastructure of SURFsara, a subsidiary of SURF cooperation, the collaborative ICT organization for Dutch education and research.