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MEASUREMENTS OF TURBULENT DIFFUSION FROM A POINT SOURCE IN UNIFORMLY SHEARED FLOW

Christina Vanderwel
Department of Mechanical Engineering University of Ottawa, Canada

Stavros Tavoularis
Department of Mechanical Engineering, University of Ottawa, Ottawa, Ontario KIN 6N5, Canada

Résumé

Turbulent diffusion of a plume of fluorescent dye with a very high Schmidt number and released from a point source in uniformly sheared flow was investigated in a water tunnel using stereoscopic particle image velocimetry and planar laser-induced fluorescence. Cross-sectional maps of the mean concentration and all three components of the turbulent mass flux vector are presented. A first-order gradient transport model relating each component of the turbulent mass flux vector to all components of the mean concentration gradient was applied successfully and all components of the associated turbulent diffusivity tensor were determined. The measured apparent diffusivities were comparable to the corresponding diffusivities. Predictions of three theoretical models were found to be in partial qualitative agreement with the measured diffusivities.