Quality of dynamic variational multiscale models on distorted grids

Abstract

The present paper focuses on a dynamic version of the variational multiscale model and investigates its performance in large eddy simulations (LES) of turbulent channel flow at Reynolds numbers (based on friction velocity) of 180, 395, and 590. The dynamic procedure was implemented for the variational multiscale model on the basis of the classical Smagorinsky model and the wall-adapting local eddy-viscosity (WALE) model. One base regular grid and three different distorted grids are employed in the evaluation. The dynamic multiscale models are compared with the direct numerical simulation (DNS) data and the conventional dynamic models. Next, the error components involved in LES are separated and the grid irregularity effect on the shortcoming of the subgrid scale models and the error of numerical approximation is assessed. A main outcome is that the dynamic multiscale models in comparison with the dynamic Smagorinsky and the dynamic WALE are less affected by grid distortion, leading to better behavior on the irregular grids.

Keywords:

• large-eddy simulation
• dynamic variational multiscale model
• channel flow
• distorted girds

Acknowledgements

This research was supported by the Flemish Science Foundation under project G.0467.05 and by IWT under the SBO project CAPRICORN No. 050163. This support is gratefully acknowledged.