LES and RANS for turbulent flow over arrays of wall-mounted obstacles
LES and RANS for turbulent flow over arrays of wall-mounted obstacles
Large-eddy simulation (LES) has been applied to calculate the turbulent flow over staggered wall-mounted cubes and staggered random arrays of obstacles with area density 25%, at Reynolds numbers between 5 × 10^3 and 5 10^6, based on the free stream velocity and the obstacle height. Re = 5 × 10^3 data were intensively validated against direct numerical simulation (DNS) results at the same Re and experimental data obtained in a boundary layer developing over an identical roughness and at a rather higher Re. The results collectively confirm that Reynolds number dependency is very weak, principally because the surface drag is predominantly form drag and the turbulence production process is at scales comparable to the roughness element sizes. LES is thus able to simulate turbulent flow over the urban-like obstacles at high Re with grids that would be far too coarse for adequate computation of corresponding smooth-wall flows. Comparison between LES and steady Reynolds-averaged Navier-Stokes (RANS) results are included, emphasising that the latter are inadequate, especially within the canopy region.
group of obstacles, bluff body, turbulent flow, reynolds number dependency
291-312
Xie, Zheng-Tong
98ced75d-5617-4c2d-b20f-7038c54f4ff0
Castro, Ian P.
66e6330d-d93a-439a-a69b-e061e660de61
2006
Xie, Zheng-Tong
98ced75d-5617-4c2d-b20f-7038c54f4ff0
Castro, Ian P.
66e6330d-d93a-439a-a69b-e061e660de61
Xie, Zheng-Tong and Castro, Ian P.
(2006)
LES and RANS for turbulent flow over arrays of wall-mounted obstacles.
Flow Turbulence and Combustion, 76 (3), .
(doi:10.1007/s10494-006-9018-6).
Abstract
Large-eddy simulation (LES) has been applied to calculate the turbulent flow over staggered wall-mounted cubes and staggered random arrays of obstacles with area density 25%, at Reynolds numbers between 5 × 10^3 and 5 10^6, based on the free stream velocity and the obstacle height. Re = 5 × 10^3 data were intensively validated against direct numerical simulation (DNS) results at the same Re and experimental data obtained in a boundary layer developing over an identical roughness and at a rather higher Re. The results collectively confirm that Reynolds number dependency is very weak, principally because the surface drag is predominantly form drag and the turbulence production process is at scales comparable to the roughness element sizes. LES is thus able to simulate turbulent flow over the urban-like obstacles at high Re with grids that would be far too coarse for adequate computation of corresponding smooth-wall flows. Comparison between LES and steady Reynolds-averaged Navier-Stokes (RANS) results are included, emphasising that the latter are inadequate, especially within the canopy region.
Text
LES_and_RANS_for_turbulent_flow_ovr_arrays_of_wall_mounted_obstacles.pdf
- Accepted Manuscript
More information
Published date: 2006
Keywords:
group of obstacles, bluff body, turbulent flow, reynolds number dependency
Organisations:
Engineering Sciences
Identifiers
Local EPrints ID: 30157
URI: http://eprints.soton.ac.uk/id/eprint/30157
ISSN: 1386-6184
PURE UUID: 93e88f20-f75b-4d5d-92e7-e7131d04c7f6
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Date deposited: 11 May 2006
Last modified: 16 Mar 2024 03:40
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