The Structure of Turbulent Channel Flow over Ratchet-Type Roughness

Busse, A. and Zhdanov, O. (2022) The Structure of Turbulent Channel Flow over Ratchet-Type Roughness. In: 12th International Symposium on Turbulence and Shear Flow Phenomena (TSFP12), Osaka, Japan, 19-22 July 2022,

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Abstract

Ratchet surfaces are a form of regular two-dimensional spanwise bar roughness where the bars have a scalene triangular cross-section. The structure of turbulent channel flow over ratchet surfaces is investigated using direct numerical simulations at Reτ = 395 for a set of five ratchet surfaces with ratchet lengths from 2k to 16k, where k is the ratchet height, in windward and leeward orientation giving a total of ten cases. The focus of this paper is the turbulent kinetic energy and the Reynolds stress anisotropy measured at the mid-cavity and the ratchet crest location. Both show strong dependence on the ratchet length and orientation. Visualisations of the instantaneous wall-normal vorticity field show that the near-wall turbulence activity is strongest at the mid-cavity location for ratchets in leeward orientation, whereas the highest turbulence activity is observed upstream of the roughness crests for ratchets in windward orientation.

Item Type:Conference Proceedings
Additional Information:This work used the Cirrus UK National Tier-2 HPC Service at EPCC (http://www.cirrus.ac.uk) funded by the University of Edinburgh and the Engineering and Physical Sciences Research Council (EP/P020267/1). A.B. gratefully acknowledges support via a Leverhulme Trust Research Fellowship for this work.
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:Busse, Dr Angela and Zhdanov, Dr Oleksandr
Authors: Busse, A., and Zhdanov, O.
College/School:College of Science and Engineering > School of Engineering
College of Science and Engineering > School of Engineering > Autonomous Systems and Connectivity
Copyright Holders:Copyright © 2022 The Authors
Publisher Policy:Reproduced with the permission of the publisher
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Project CodeAward NoProject NamePrincipal InvestigatorFunder's NameFunder RefLead Dept
309538Rough-wall turbulence: the Lagrangian viewAngela BusseLeverhulme Trust (LEVERHUL)RF-2020-498\9ENG - Autonomous Systems & Connectivity