Timofey Mukha: Towards Accurate Wall-Modelled Large Eddy Simulation

Abstract:

Large eddy simulation (LES), is a scale-resolving turbulence modelling approach used in academic research and industry when conventional turbulence modelling fails to provide accurate results. Unfortunately, when it comes wall-bounded flows at high Reynolds numbers, LES is prohibitively computationally expensive. It can be shown that 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 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 finite volume discretization. Results from WMLES of several canonical turbulent flows will be demonstrated and the influence of several modelling choices examined. Finally, promising early results from newly developed wall-stress models will be demonstrated.

Recommended reading:

Larsson, J., Kawai, S., Bodart, J., & Bermejo-Moreno, I. (2016). Large eddy simulation with modeled wall-stress: recent progress and future directions. Mechanical Engineering Reviews, 3(1), 1–23. URL: doi.org/10.1299/mer.15-00418

Rezaeiravesh, S., Liefvendahl, M., & Fureby, C. (2016). On grid resolution requirements for LES of wall-bounded flows. In ECCOMAS Congress 2016, Crete, Greece. URL: www.eccomas2016.org/proceedings/pdf/7105.pdf

Liefvendahl, M., Mukha, T., & Rezaeiravesh, S. (2017). Formulation of a wall model for LES in a collocated finite-volume framework. URL: uu.diva-portal.org/smash/record.jsf?pid=diva2%3A1069325

Mukha, T., Rezaeiravesh, S., & Liefvendahl, M. (2017). An OpenFOAM library for wall-modelled Large-Eddy Simulation. In 12th OpenFOAM Workshop. URL: openconf.org/ofw12/modules/request.php?module=oc_program&action=summary.php&id=89