Scale-by-scale energy budget in fractal element grid-generated turbulence
Scale-by-scale energy budget in fractal element grid-generated turbulence
Measurements were conducted downstream of a square-fractal-element grid at , where L0 is the size of the largest element in the grid. The scale-by-scale energy budget for grid turbulence is used to investigate the phenomenological change in the turbulence between the inhomogeneous and homogeneous regions downstream of the grid, providing greater insight into the evolution of the turbulence in these two regions. It is shown that in the far field, x/L0 ? 20, where the flow is approximately homogeneous and isotropic, the scale-by-scale energy budget for grid turbulence is well balanced. In the near field, x/L0 < 20, the same energy budget is not satisfied, with the imbalance of the budget occurring at scales in the range ? ? r ? L0. It is proposed that the imbalance is caused by non-zero transverse transport of turbulent kinetic energy and production due to transverse mean velocity gradients. Approach of the spectra to k?5/3 behaviour with a decade long scaling range in the inhomogeneous region is attributed to forcing by these non-zero transverse terms.
grid turbulence, homogenous turbulence, isotropic turbulence, energy budget, fractal grid
540-554
Hearst, R. Jason
965708e6-ddf4-4cbb-af74-866bb4cdb4de
Lavoie, Philippe
04aaae82-b9ba-420a-a1c0-3df4f08b3306
2 June 2014
Hearst, R. Jason
965708e6-ddf4-4cbb-af74-866bb4cdb4de
Lavoie, Philippe
04aaae82-b9ba-420a-a1c0-3df4f08b3306
Hearst, R. Jason and Lavoie, Philippe
(2014)
Scale-by-scale energy budget in fractal element grid-generated turbulence.
Journal of Turbulence, 15 (8), .
(doi:10.1080/14685248.2014.916041).
Abstract
Measurements were conducted downstream of a square-fractal-element grid at , where L0 is the size of the largest element in the grid. The scale-by-scale energy budget for grid turbulence is used to investigate the phenomenological change in the turbulence between the inhomogeneous and homogeneous regions downstream of the grid, providing greater insight into the evolution of the turbulence in these two regions. It is shown that in the far field, x/L0 ? 20, where the flow is approximately homogeneous and isotropic, the scale-by-scale energy budget for grid turbulence is well balanced. In the near field, x/L0 < 20, the same energy budget is not satisfied, with the imbalance of the budget occurring at scales in the range ? ? r ? L0. It is proposed that the imbalance is caused by non-zero transverse transport of turbulent kinetic energy and production due to transverse mean velocity gradients. Approach of the spectra to k?5/3 behaviour with a decade long scaling range in the inhomogeneous region is attributed to forcing by these non-zero transverse terms.
Text
fractal2_jot_sbsb_final.pdf
- Accepted Manuscript
More information
Accepted/In Press date: 12 April 2014
Published date: 2 June 2014
Keywords:
grid turbulence, homogenous turbulence, isotropic turbulence, energy budget, fractal grid
Organisations:
Aerodynamics & Flight Mechanics Group
Identifiers
Local EPrints ID: 376369
URI: http://eprints.soton.ac.uk/id/eprint/376369
ISSN: 1468-5248
PURE UUID: f4895b32-58ab-4b05-9002-8a83e65f77c8
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Date deposited: 27 Apr 2015 10:46
Last modified: 14 Mar 2024 19:41
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Contributors
Author:
R. Jason Hearst
Author:
Philippe Lavoie
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