What is it about?

This paper employs Zonal Detached Eddy Simulation for the simulation and analysis of high Reynolds number turbulent boundary layers with pressure gradients and mild flow separation. The demanding test cases considered are of particular interest due to the high Reynolds number which makes them too expensive for performing simulation by means of WRLES (Wall-Resolved Large Eddy Simulation) or DNS (Direct Numerical Simulation) at an affordable computational effort.

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Why is it important?

The simulation of turbulent flows at Reynolds numbers of industrial applications by means of DNS (Direct Numerical Simulation) or WRLES (Wall-Resolved Large Eddy Simulation) is usually prohibitive due to the high computational effort. The Zonal Detached Eddy Simulation mode 3 (which corresponds to a Wall-Modelled Large Eddy Simulation approach) allows for a significant decrease of the computational effort compared to WRLES or DNS and therefore reaching higher Reynolds numbers becomes achievable. This paper shows the advantage of employing ZDES mode 3 in the particular example presented of non-canonical turbulent boundary layers, where RANS models (Reynolds-Averaged Navier Stokes) are less accurate. Besides, turbulence is partly resolved by ZDES mode 3, thus allowing for more in depth analysis of turbulence dynamics, which is done in the present paper by means of spectral analysis and the assessment of a convection velocity of turbulent structures dependent on their length scale.

Perspectives

This work focuses on a turbulent boundary layer experiencing pressure gradients at high Reynolds numbers. The satisfactory results obtained by Zonal Detached Eddy Simulation mode 3 suggest that it could be successfully applied to the simulation of other non-canonical wall-bounded flows. For instance, as presented at the end of the paper, ZDES mode 3 is going to be employed for the simulation of high Reynolds numbers turbulent boundary layers experiencing mild separation and recovering from non-equilibrium conditions downstream of reattachment. In the mentioned test case, in depth analysis of turbulence will also be performed, akin to that of the present paper.

Jaime Vaquero
ONERA

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This page is a summary of: Assessment of ZDES for WMLES of turbulent boundary layers with pressure gradient and mild flow separation, July 2021, American Institute of Aeronautics and Astronautics (AIAA),
DOI: 10.2514/6.2021-2811.
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