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Extension of roughness noise to bluff bodies using the boundary element method

Extension of roughness noise to bluff bodies using the boundary element method
Extension of roughness noise to bluff bodies using the boundary element method
A prediction model of roughness noise generated by bluff body flow at high Reynolds numbers is proposed. Howe's roughness noise theory extended by Liu and Dowling is used, and the boundary layer inputs to the theory have been modified for a bluff body. The scattering due to the bluff body has been accounted for by the boundary element method. The procedure to couple the roughness noise sources to the tailored Green's function is detailed for the case where the boundary element method mesh is orthogonal and aligned with the boundary layer outer velocity. The proposed method has been implemented and compared to experimental results for the particular case of a circular cylinder with large roughness. Two different estimations of the skin friction, which is an input to the roughness noise theory, are considered. One is a zero-pressure gradient model, and the second is based on published experimental data of the skin friction on a rough circular cylinder, but with smaller roughness than was used in the experiments. The zero-pressure gradient skin friction estimate leads to a better prediction of the effect of changes in the area covered by roughness elements. The success of the zero-pressure gradient skin friction estimate is encouraging as the only modifications that need to be made to the boundary layer model to account for a bluff body are the boundary layer outer velocity distribution and the location of separation.
0022-460X
318–337
Alomar, Antoni
8620bb97-69fb-4183-92b8-04b0e88a56f9
Angland, David
b86880c6-31fa-452b-ada8-4bbd83cda47f
Zhang, Xin
3056a795-80f7-4bbd-9c75-ecbc93085421
Alomar, Antoni
8620bb97-69fb-4183-92b8-04b0e88a56f9
Angland, David
b86880c6-31fa-452b-ada8-4bbd83cda47f
Zhang, Xin
3056a795-80f7-4bbd-9c75-ecbc93085421

Alomar, Antoni, Angland, David and Zhang, Xin (2018) Extension of roughness noise to bluff bodies using the boundary element method. Journal of Sound and Vibration, 414, 318–337. (doi:10.1016/j.jsv.2017.09.021).

Record type: Article

Abstract

A prediction model of roughness noise generated by bluff body flow at high Reynolds numbers is proposed. Howe's roughness noise theory extended by Liu and Dowling is used, and the boundary layer inputs to the theory have been modified for a bluff body. The scattering due to the bluff body has been accounted for by the boundary element method. The procedure to couple the roughness noise sources to the tailored Green's function is detailed for the case where the boundary element method mesh is orthogonal and aligned with the boundary layer outer velocity. The proposed method has been implemented and compared to experimental results for the particular case of a circular cylinder with large roughness. Two different estimations of the skin friction, which is an input to the roughness noise theory, are considered. One is a zero-pressure gradient model, and the second is based on published experimental data of the skin friction on a rough circular cylinder, but with smaller roughness than was used in the experiments. The zero-pressure gradient skin friction estimate leads to a better prediction of the effect of changes in the area covered by roughness elements. The success of the zero-pressure gradient skin friction estimate is encouraging as the only modifications that need to be made to the boundary layer model to account for a bluff body are the boundary layer outer velocity distribution and the location of separation.

Text Extension of roughness noise to bluff bodies using the boundary element method - Accepted Manuscript
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More information

Accepted/In Press date: 18 September 2017
e-pub ahead of print date: 1 December 2017
Published date: 3 February 2018

Identifiers

Local EPrints ID: 414484
URI: https://eprints.soton.ac.uk/id/eprint/414484
ISSN: 0022-460X
PURE UUID: c72749ea-f3c8-4a82-a7b7-7cc3bced5826

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Date deposited: 02 Oct 2017 16:30
Last modified: 03 Feb 2018 17:30

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