DNS of Turbulent Channel Flow over Engineering Rough Surfaces

Busse, A. , Tyson, C. J., Sandham, N. D. and Luetzner, M. (2013) DNS of Turbulent Channel Flow over Engineering Rough Surfaces. In: 8th International Symposium on Turbulence and Shear Flow Phenomena, Poitiers, France, 28-30 Aug 2013,

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Publisher's URL: http://www.tsfp-conference.org/proceedings/2013/v2/tbl4a.pdf


Most rough surfaces found in engineering applications are irregular and possess features on multiple length scales. In these respects they differ considerably from standard roughness models, such as arrays of cubes, used in most experiments and numerical simulations investigating turbulent flow over rough surfaces. Results from direct numerical simulations of turbulent channel flow at Ret = 180 over realistic representations of typical engineering rough surfaces are presented in this paper. The surface geometries are based on surface scans of four different materials: graphite, carbon-carbon composite, shotblasted and ground steel. The roughness function DU+ shows a strong dependence on the three-dimensional topography of the surfaces and is not solely determined by the physical roughness height. The dependence of the roughness function on various characteristic topological surface parameters has been tested. As expected, the roughness function increases with the surface skewness and the effective slope. It is also found that the roughness function decreases with increasing surface bearing index. The surface anisotropy and the texture direction of the surface with respect to the mean flow direction has an additional effect on the roughness function. Of the normal Reynolds stresses, only the streamwise stress shows a clear correlation to the degree of roughness of the surface. The spanwise and wall-normal stresses are largely unaffected by the degree of roughness and the roughness type outside the roughness sub-layer.

Item Type:Conference Proceedings
Glasgow Author(s) Enlighten ID:Busse, Dr Angela
Authors: Busse, A., Tyson, C. J., Sandham, N. D., and Luetzner, M.
College/School:College of Science and Engineering > School of Engineering > Systems Power and Energy
Journal Name:Journal of Fluid Mechanics
Publisher:Cambridge University Press
Copyright Holders:Copyright © 2013 The Authors
Publisher Policy:Reproduced with the permission of the authors

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