A-posteriori assessment of Large-Eddy Simulation subgrid-closures for momentum and scalar fluxes in a turbulent premixed burner experiment

Although overall increasing computing power allows for higher resolution in Large-Eddy Simulation (LES), an appropriate choice of the subgrid-model is still decisive for the simulation quality. The relevance of the subgrid-model increases even further, if transported quantities are used in additional thermo-chemical models, which are coupled to the flow field. The present study investigates the impact of the choice of the subgrid-model for reactive flows in LES in the context of tabulated chemistry using well known and recently suggested modifications of eddy viscosity and scale-similarity-type models. LES calculations of the well investigated Cambridge stratified swirl burner have been performed with flamelet generated manifolds in combination with artificial flame-thickening. The simulations have been compared with flame-resolved results using the same numerical setup. Encouraging results have been obtained for a regularized scale-similarity-type model (applied to momentum- and scalar-fluxes). The sensor-enhanced Smagorinsky model outperforms well known eddy viscosity models while maintaining stability and being straight forward to implement with very low computational overhead compared to the static Smagorinsky model.