Article: Kemenov KA, Wang HF and Pope SB (2012). “Turbulence Resolution Scale Dependence in Large-Eddy Simulations of a Jet Flame.” Flow Turbulence and Combustion 88(4): 529-561.
Abstract: The explicit dependence of LES fields on the turbulence resolution scale Delta implies that LES statistics usually vary with Delta and exhibit different convergence behaviors for different types of statistics, flow variables and subgrid LES models. The present work compares the performance of two popular subgrid models-the dynamic Smagorinsky model and the Vreman model-based on the convergence of their LES statistics with respect to Delta for a piloted methane-air (Sandia D) flame. The Delta-dependence of the LES statistics is studied based on five grids with progressively increased resolution ranging from 3 x 10(5) to about 10.4 x 10(6) cells. The simulation results show that the resolved velocity statistics converge for the finest grids with some weak Delta-dependence observed in the variance fields. The mixture fraction statistics are found to be more sensitive to the turbulence resolution scale upstream in the flame signifying the importance of the estimation of the Delta-invariant LES statistics at the DNS limit. For the considered flame the Vreman subgrid model exhibits good performance with the statistics being very close to those given by the dynamic Smagorinsky model, and being rather insensitive to a choice of the model constant.