Surface-sampled simulations of turbulent flow at high Reynolds number
Surface-sampled simulations of turbulent flow at high Reynolds number
A new approach to turbulence simulation, based on a combination of large-eddy simulation (LES) for the whole flow and an array of non-space-filling quasi-direct numerical simulations (QDNS), which sample the response of near-wall turbulence to large-scale forcing, is proposed and evaluated. The technique overcomes some of the cost limitations of turbulence simulation, since the main flow is treated with a coarse-grid LES, with the equivalent of wall functions supplied by the near-wall sampled QDNS. Two cases are tested, at friction Reynolds number Reτ=4200 and 20,000. The total grid node count for the first case is less than half a million and less than two million for the second case, with the calculations only requiring a desktop computer. A good agreement with published DNS is found at Reτ=4200, both in terms of the mean velocity profile and the streamwise velocity fluctuation statistics, which correctly show a substantial increase in near-wall turbulence levels due to a modulation of near-wall streaks by large-scale structures. The trend continues at Reτ=20,000, in agreement with experiment, which represents one of the major achievements of the new approach. A number of detailed aspects of the model, including numerical resolution, LES-QDNS coupling strategy and sub-grid model are explored. A low level of grid sensitivity is demonstrated for both the QDNS and LES aspects. Since the method does not assume a law of the wall, it can in principle be applied to flows that are out of equilibrium.
Turbulence models, Turbulent flow, LES: Large Eddy Simulations, Navier-Stokes, Incompressible flow, Finite difference
525-537
Sandham, Neil
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Johnstone, Roderick
8ac02aa2-776b-4f80-b44d-1a5cf8682f21
Jacobs, Christian
0ffde78b-6ae2-4b44-a916-666f6be2b92c
30 November 2017
Sandham, Neil
0024d8cd-c788-4811-a470-57934fbdcf97
Johnstone, Roderick
8ac02aa2-776b-4f80-b44d-1a5cf8682f21
Jacobs, Christian
0ffde78b-6ae2-4b44-a916-666f6be2b92c
Sandham, Neil, Johnstone, Roderick and Jacobs, Christian
(2017)
Surface-sampled simulations of turbulent flow at high Reynolds number.
International Journal for Numerical Methods in Fluids, 85 (9), .
(doi:10.1002/fld.4395).
Abstract
A new approach to turbulence simulation, based on a combination of large-eddy simulation (LES) for the whole flow and an array of non-space-filling quasi-direct numerical simulations (QDNS), which sample the response of near-wall turbulence to large-scale forcing, is proposed and evaluated. The technique overcomes some of the cost limitations of turbulence simulation, since the main flow is treated with a coarse-grid LES, with the equivalent of wall functions supplied by the near-wall sampled QDNS. Two cases are tested, at friction Reynolds number Reτ=4200 and 20,000. The total grid node count for the first case is less than half a million and less than two million for the second case, with the calculations only requiring a desktop computer. A good agreement with published DNS is found at Reτ=4200, both in terms of the mean velocity profile and the streamwise velocity fluctuation statistics, which correctly show a substantial increase in near-wall turbulence levels due to a modulation of near-wall streaks by large-scale structures. The trend continues at Reτ=20,000, in agreement with experiment, which represents one of the major achievements of the new approach. A number of detailed aspects of the model, including numerical resolution, LES-QDNS coupling strategy and sub-grid model are explored. A low level of grid sensitivity is demonstrated for both the QDNS and LES aspects. Since the method does not assume a law of the wall, it can in principle be applied to flows that are out of equilibrium.
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heterogeneous_modelling_les_qdns_author_accepted_manuscript
- Accepted Manuscript
Text
Sandham_et_al-2017-International_Journal_for_Numerical_Methods_in_Fluids
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More information
Submitted date: 7 October 2016
Accepted/In Press date: 26 April 2017
e-pub ahead of print date: 7 June 2017
Published date: 30 November 2017
Keywords:
Turbulence models, Turbulent flow, LES: Large Eddy Simulations, Navier-Stokes, Incompressible flow, Finite difference
Organisations:
Aeronautics, Astronautics & Comp. Eng, Aerodynamics & Flight Mechanics Group
Identifiers
Local EPrints ID: 410720
URI: http://eprints.soton.ac.uk/id/eprint/410720
ISSN: 0271-2091
PURE UUID: b0207454-c934-44dc-a1ae-dff360304428
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Date deposited: 09 Jun 2017 09:27
Last modified: 16 Mar 2024 05:16
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Contributors
Author:
Neil Sandham
Author:
Roderick Johnstone
Author:
Christian Jacobs
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