Conference Proceedings

Turbulent flow over spanwise-varying roughness in a minimal streamwise channel

MX Xie, D Chung, N Hutchins

Journal of Physics: Conference Series, Volume 1522, Fourth Madrid Summer School on Turbulence 10 June to 12 July 2019, Madrid, Spain | IOP Publishing | Published : 2020

Abstract

All rights reserved. We report direct numerical simulations in a minimal streamwise domain of turbulent channel flow over spanwise-alternating patches of rough and smooth walls. Despite the minimal streamwise domain overpredicting streamwise-velocity fluctuations and inhibiting the meandering of long turbulent structures, it captures the rotational behaviour of mean secondary flows also observed in other studies with spanwise-varying roughness. To extend the study of spanwise-varying roughness, we prescribe a lateral velocity to the wall roughness to mimic flow over oblique patches of roughness. Far from the wall, long-lived turbulent structures are convected in the direction of the moving r..

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