ABSTRACT CTS-9408344 CHARLES MENEVEAU JOHNS HOPKINS UNIVERSITY The proposed research is an experimental study of turbulence small-scales from the point of view of subgrid modeling fop Large-Eddy-Simulation, a technique of increasing engineering usefulness in dealing with the `turbulence problem'. The measurements are to be performed at high Reynolds numbers, using multi-component hot-wire anemometry. The main flow to be studied is the `complex wake', a free shear-flow that displays both a non-monotonic energy spectrum as well as spatial complexity. Comparisons between real and modeled subgrid stresses will be performed using several reference quantities. For example, the rate at which the real stress dissipates large-scale kinetic energy will be compared to the rate of dissipation accomplished by the models. Other quantities on which the comparisons will be based relate to energy spectra, enstrophy, probability-density functions, correlation coefficients, etc. Measurements will be performed across distinct flow regions and regimes, in order to explore the impact of complex geometry. Also, the analysis will be based on a wide range of length-scales or filter sizes, in order to ascertain the effect of the spectral complexity (e.g. spectral `humps') expected in regions of the proposed flow-field. Models that will be scrutinized include eddy-viscosity models, similarity and non-linear models, global and local dynamic models, etc.. This research is expected to significantly contribute to the foundation of Large-Eddy-Simulation and associated modeling in complex flow conditions, based on real data at high Reynolds numbers.
