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Direct numerical simulation of turbulent flow over a rough surface based on a surface scan

Direct numerical simulation of turbulent flow over a rough surface based on a surface scan
Direct numerical simulation of turbulent flow over a rough surface based on a surface scan
Typical engineering rough surfaces show only limited resemblance to the artificially constructed rough surfaces that have been the basis of most previous fundamental research on turbulent flow over rough walls. In this article flow past an irregular rough surface is investigated, based on a scan of a rough graphite surface that serves as a typical example for an irregular rough surface found in engineering applications. The scanned map of surface height versus lateral coordinates is filtered in Fourier space to remove features on very small scales and to create a smoothly varying periodic representation of the surface. The surface is used as a no-slip boundary in direct numerical simulations of turbulent channel flow. For the resolution of the irregular boundary an iterative embedded boundary method is employed. The effects of the surface filtering on the turbulent flow are investigated by studying a series of surfaces with decreasing level of filtering. Mean flow, Reynolds stress and dispersive stress profiles show good agreement once a sufficiently large number of Fourier modes are retained. However, significant differences are observed if only the largest surface features are resolved. Strongly filtered surfaces give rise to a higher mean-flow velocity and to a higher variation of the streamwise velocity in the roughness layer compared with weakly filtered surfaces. In contrast, for the weakly filtered surfaces the mean flow is reversed over most of the lower part of the roughness sublayer and higher levels of dispersive shear stress are found.
0045-7930
129-147
Busse, Angela
892e26d7-dc9a-4786-b105-0e8118e04fef
Luetzner, Mark
4561206d-cebc-4a95-bed0-9797aaca29cb
Sandham, N.D.
0024d8cd-c788-4811-a470-57934fbdcf97
Busse, Angela
892e26d7-dc9a-4786-b105-0e8118e04fef
Luetzner, Mark
4561206d-cebc-4a95-bed0-9797aaca29cb
Sandham, N.D.
0024d8cd-c788-4811-a470-57934fbdcf97

Busse, Angela, Luetzner, Mark and Sandham, N.D. (2015) Direct numerical simulation of turbulent flow over a rough surface based on a surface scan. Computers & Fluids, 116, 129-147. (doi:10.1016/j.compfluid.2015.04.008).

Record type: Article

Abstract

Typical engineering rough surfaces show only limited resemblance to the artificially constructed rough surfaces that have been the basis of most previous fundamental research on turbulent flow over rough walls. In this article flow past an irregular rough surface is investigated, based on a scan of a rough graphite surface that serves as a typical example for an irregular rough surface found in engineering applications. The scanned map of surface height versus lateral coordinates is filtered in Fourier space to remove features on very small scales and to create a smoothly varying periodic representation of the surface. The surface is used as a no-slip boundary in direct numerical simulations of turbulent channel flow. For the resolution of the irregular boundary an iterative embedded boundary method is employed. The effects of the surface filtering on the turbulent flow are investigated by studying a series of surfaces with decreasing level of filtering. Mean flow, Reynolds stress and dispersive stress profiles show good agreement once a sufficiently large number of Fourier modes are retained. However, significant differences are observed if only the largest surface features are resolved. Strongly filtered surfaces give rise to a higher mean-flow velocity and to a higher variation of the streamwise velocity in the roughness layer compared with weakly filtered surfaces. In contrast, for the weakly filtered surfaces the mean flow is reversed over most of the lower part of the roughness sublayer and higher levels of dispersive shear stress are found.

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More information

Accepted/In Press date: 6 April 2015
Published date: 15 August 2015
Organisations: Aerodynamics & Flight Mechanics Group

Identifiers

Local EPrints ID: 377533
URI: https://eprints.soton.ac.uk/id/eprint/377533
ISSN: 0045-7930
PURE UUID: 58ce1ef8-7c2c-4103-ab33-379deb881095
ORCID for N.D. Sandham: ORCID iD orcid.org/0000-0002-5107-0944

Catalogue record

Date deposited: 12 Jun 2015 07:56
Last modified: 06 Jun 2018 12:55

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