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Effect of turbulence on the wake of a wall-mounted cube

Effect of turbulence on the wake of a wall-mounted cube
Effect of turbulence on the wake of a wall-mounted cube
The influence of turbulence on the flow around a wall-mounted cube immersed in a turbulent boundary layer is investigated experimentally with particle image velocimetry and hot-wire anemometry. Free-stream turbulence is used to generate turbulent boundary layer profiles where the normalised shear at the cube height is fixed, but the turbulence intensity at the cube height is adjustable. The free-stream turbulence is generated with an active grid and the turbulent boundary layer is formed on an artificial floor in a wind tunnel. The boundary layer development Reynolds number ($Re_x$) and the ratio of the cube height ($h$) to the boundary layer thickness ($\delta$) are held constant at $Re_x = 1.8 \times 10^6$ and $h/\delta = 0.47$. It is demonstrated that the stagnation point on the upstream side of the cube and the reattachment length in the wake of the cube are independent of the incoming profile for the conditions investigated here. In contrast, the wake length monotonically decreases for increasing turbulence intensity but fixed normalised shear---both quantities measured at the cube height. The wake shortening is a result of heightened turbulence levels promoting wake recovery from high local velocities and the reduction in strength of a dominant shedding frequency.
0022-1120
513-530
Hearst, Jason
965708e6-ddf4-4cbb-af74-866bb4cdb4de
Gomit, Guillaume
81e53723-d65a-46f5-bfc5-4ada63f6c5a9
Ganapathisubramani, Bharath
5e69099f-2f39-4fdd-8a85-3ac906827052
Hearst, Jason
965708e6-ddf4-4cbb-af74-866bb4cdb4de
Gomit, Guillaume
81e53723-d65a-46f5-bfc5-4ada63f6c5a9
Ganapathisubramani, Bharath
5e69099f-2f39-4fdd-8a85-3ac906827052

Hearst, Jason, Gomit, Guillaume and Ganapathisubramani, Bharath (2016) Effect of turbulence on the wake of a wall-mounted cube. Journal of Fluid Mechanics, 804, 513-530. (doi:10.1017/jfm.2016.565).

Record type: Article

Abstract

The influence of turbulence on the flow around a wall-mounted cube immersed in a turbulent boundary layer is investigated experimentally with particle image velocimetry and hot-wire anemometry. Free-stream turbulence is used to generate turbulent boundary layer profiles where the normalised shear at the cube height is fixed, but the turbulence intensity at the cube height is adjustable. The free-stream turbulence is generated with an active grid and the turbulent boundary layer is formed on an artificial floor in a wind tunnel. The boundary layer development Reynolds number ($Re_x$) and the ratio of the cube height ($h$) to the boundary layer thickness ($\delta$) are held constant at $Re_x = 1.8 \times 10^6$ and $h/\delta = 0.47$. It is demonstrated that the stagnation point on the upstream side of the cube and the reattachment length in the wake of the cube are independent of the incoming profile for the conditions investigated here. In contrast, the wake length monotonically decreases for increasing turbulence intensity but fixed normalised shear---both quantities measured at the cube height. The wake shortening is a result of heightened turbulence levels promoting wake recovery from high local velocities and the reduction in strength of a dominant shedding frequency.

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cube_jfm_paper_final.pdf - Accepted Manuscript
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More information

Submitted date: 6 March 2016
Accepted/In Press date: 22 August 2016
e-pub ahead of print date: 9 September 2016
Published date: October 2016
Organisations: Aerodynamics & Flight Mechanics Group

Identifiers

Local EPrints ID: 400432
URI: http://eprints.soton.ac.uk/id/eprint/400432
ISSN: 0022-1120
PURE UUID: 326a2a69-3c2b-42a7-ae8d-157d148f0c6e
ORCID for Bharath Ganapathisubramani: ORCID iD orcid.org/0000-0001-9817-0486

Catalogue record

Date deposited: 16 Sep 2016 10:40
Last modified: 15 Mar 2024 05:53

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Author: Jason Hearst
Author: Guillaume Gomit

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