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Large-eddy and wall-modelled simulations of turbulent flow over two-dimensional river dunes

Nokhandan, M. M., Piomelli, U. & Omidyeganeh, M. ORCID: 0000-0002-4140-2810 (2018). Large-eddy and wall-modelled simulations of turbulent flow over two-dimensional river dunes. Physics and Chemistry of the Earth, doi: 10.1016/j.pce.2018.11.004

Abstract

Turbulence models based on the Spalart-Allmaras Detached-Eddy Simulation (DES) approach are used to compute the turbulent flow over a two-dimensional dune geometry. DES was developed for massively separated flows, but has been applied as a wall model to attached flows as well. In attached shear layers, however, the lack of resolved eddies in the region where the model switches from a turbulence model to a Subfilter-Scale (SFS) one, results in an underprediction of the wall stress, and a shift in the logarithmic layer. The dune studied here is neither a fully attached flow nor a massively separated one, and allows us to investigate the accuracy of DES wall-models in intermediate cases of this type. Results are compared to a well-validated Large-Eddy Simulation (LES) database. DES based methods are found to be more accurate in this application, compared to attached boundary layers. All the methods required approximately 3% of the CPU time of the wall-resolved LES simulations. All methods gave similar results, but the Improved Delayed Detached Eddy Simulation seemed preferable because of the consistency of the trends it predicted.

Publication Type: Article
Additional Information: © Elsevier 2018. This manuscript version is made available under the CC-BY-NC-ND 4.0 license http://creativecommons.org/licenses/by-nc-nd/4.0/
Publisher Keywords: River dunes, Detached-Eddy Simulation, Large-Eddy Simulation, Wall-Modelled LES
Subjects: G Geography. Anthropology. Recreation > GB Physical geography
Q Science > QA Mathematics > QA75 Electronic computers. Computer science
T Technology > TL Motor vehicles. Aeronautics. Astronautics
Departments: School of Science & Technology > Engineering
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