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Seminar: Fluid Mechanics

Wall-modelled large eddy simulation using a general-purpose CFD code

Speaker: Timofey Mukha
Organization: Uppsala University
Time: 2018-05-03 10:30
Place: Teknikringen 8

Abstract

It is well known that large eddy simulation (LES) of high Reynolds number wall-bounded flows is prohibitively computationally expensive. The computational effort is driven by the need for resolving the energetic structures in the inner layer of turbulent boundary layers (TBLs). This is the main motivation behind wall-modelled (WM)LES, which aims at introducing special modelling near the wall that would account for the dynamics of the inner layer, thus alleviating the need to resolve it with the LES grid. Many approaches to WMLES exist, but arguably the most wide-spread is so-called wall-stress modelling, which aims at incorporating the effect of inner-layer dynamics by predicting and enforcing the correct local value of the wall shear stress. Interestingly, despite several decades of WMLES research, no well-established guidelines exist for many modelling choices, such as necessary grid resolution, grid-cell topology, numerical schemes, subgrid-scale modelling, etc. The given talk will provide an introduction to WMLES, which will be followed by a deeper discussion of wall-stress models, in particular, their formulation and implementation in the framework of a general-purpose CFD code. Results from WMLES of several canonical turbulent flows will be demonstrated and the influence of several modelling choices examined.