Extended Abstract (260K)8.6
The effect of eigenvector alignments on subgrid-scale dissipation of turbulent kinetic energy
Chad Higgins, Johns Hopkins University, Baltimore, MD; and C. Meneveau and M. Parlange
A geometric interpretation of kinetic energy dissipation in large eddy simulations is derived. With this formulation, the dependence of subgrid-scale (SGS) dissipation on alignment angles between the eigendirections of the SGS stress and the filtered strain rate tensors is explicitly known. It can be used to interpret the recent field and laboratory (Higgins et al. 2002, Tao et al. 2002) observations that quantify statistics of the eigenvector alignment trends. Among others, the observations show that the dissipation conditionally averaged on the so-called strain state parameter, s*, peaks at s*=1 indicating that high SGS dissipation is associated with axisymmetric extending motions. We use the newly developed geometric formulation to predict the main trends of dissipation as a function of s*. Predictions are compared to field data (Davis 1999 experiment) obtained from arrays of sonic anemometers.
Session 8, Fundamental Studies of the ABL
Tuesday, 16 July 2002, 3:30 PM-5:30 PM
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