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ASSESSMENT OF SUBGRID SCALAR MIXING MODELS FOR LES OF REACTING FLOWS

Olivia S. Sun
Applied Fluid Imaging Laboratory Department of Mechanical Engineering The Johns Hopkins University Baltimore, Maryland 21218 USA

Lester K. Su
Johns Hopkins University, Department of Mechanical Engineering, Baltimore, MD, USA

Abstrakt

LES models for subgrid scalar dissipation are tested a priori using experimental data from an axisymmetric, turbulent, co-flowing jet. The 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, which can be assessed by computing a correlation coefficient between exact and modeled terms. We also examine some of the fundamental assumptions underlying the models. Results suggest that assumptions of time-scale proportionality are more valid than those of local equilibrium.