SIGLEAvailable from British Library Document Supply Centre-DSC:m00/11571 / BLDSC - British Library Document Supply CentreGBUnited Kingdo

Busse, Angela

Luetzner, Mark

Sandham, Neil D.

Tyson, Chris J.

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

Enlighten: Publications

DNS of Turbulent Channel Flow over Engineering Rough Surfaces

Enlighten

English

Department of Trade and Industry, London (United Kingdom). Information Society Initiative

OpenGrey Repository