Graduate Aeronautical Laboratories
California Institute of Technology
Some aspects of the utility of vortex dynamics in the prediction of the properties of turbulence will be discussed. This will be followed by a brief outline of the large-eddy simulation (LES) method for the computation of turbulent flows at moderate to high Reynolds numbers. A vortex-dynamics approach to the modeling of subgrid turbulence scales for LES will be then be described. This is the `stretched-vortex', model in which the unresolved (subgrid) velocity field is modeled by nearly axisymmetric subgrid vortices - one or more per grid point - whose axis alignments are related to the local resolved-flow velocity gradients. The subgrid stresses produced by the vortices are proportional to the product of the vortex energy and a second-order tensor determined by the vortex axis directions. Applications of the model to decaying turbulence, incompressible turbulent channel flow at moderate Reynolds numbers, and to the statistics of a passive scalar in forced isotropic turbulence will be described.
Please join us for refreshments before the lecture at 2:30p.m. in room 353 Jabara Hall.
[ Spring 2000]