Joint experimental and numerical studies of subgrid scalar mixing models for LES

LES models for subgrid scalar transport and dissipation are assessed through joint experimental and numerical studies using experimental data from an axisymmetric, turbulent, co-flowing jet, and large eddy simulation of scalar mixing in a round turbulent jet. The dissipation models tested include: a gradient-based model, which is based on a local equilibrium assumption, a model that assumes proportionality between mechanical and scalar time scales, and a dynamic structure model based on scale-similarity ideas. Of primary interest is the structural accuracy of the models and the fundamental assumptions underlying the models. Results suggest that assumptions of time-scale proportionality are more valid than those of local equilibrium. Performance of scalar transport models is analyzed by examining mean resolved-scale quantities obtained from LES.