A dynamic mixed subgrid-scale model and its application to turbulent recirculating flows

TLDR

The dynamic subgrid‑scale eddy viscosity model of Germano et al. and Bardina et al.’s mixed model form the foundation of the new dynamic mixed subgrid‑scale model. The new dynamic mixed model explicitly calculates the modified Leonard term, models only the cross term and SGS Reynolds stress, computes its coefficient from local flow variables, and is implemented in a finite‑volume LES framework for lid‑driven cavity flows. The model retains DSM’s favorable features, does not require alignment of stress and strain axes, achieves better agreement with experimental data at Reynolds numbers up to 10 000, and yields a smaller dynamically computed coefficient than DSM.

Abstract

The dynamic subgrid-scale eddy viscosity model of Germano et al. [Phys. Fluids A 3, 1760 (1991)] (DSM) is modified by employing the mixed model of Bardina et al. [Ph.D dissertation, Stanford University (1983)] as the base model. The new dynamic mixed model explicitly calculates the modified Leonard term and only models the cross term and the SGS Reynolds stress. It retains the favorable features of DSM and, at the same time, does not require that the principal axes of the stress tensor be aligned with those of the strain rate tensor. The model coefficient is computed using local flow variables. The new model is incorporated in a finite-volume solution method and large-eddy simulations of flows in a lid-driven cavity at Reynolds numbers of 3200, 7500, and 10 000 show excellent agreement with the experimental data. Better agreement is achieved by using the new model compared to the DSM. The magnitude of the dynamically computed model coefficient of the new model is significantly smaller than that from DSM.