The results of a laboratory investigation on turbulent mixing of mass and momentum associated with the collapse of Kelvin-Helmholtz waves which develop in a stably stratified parallel shear layer with Schmidt number are presented. The waves were generated in a stratified, tilting tank using a denser fluid underlying a lighter fluid with a velocity shear between the layers. Detailed velocity and density measurements were conducted simultaneously using particle tracking velocimetry and laser-induced fluorescence techniques. Estimation of the efficiency of mixing, the ratio between the diffusive flux of density responsible for mixing, to the turbulent kinetic energy dissipation rate, suggest it is independent of the initial values of the Reynolds and the bulk Richardson numbers. The measurements of the eddy diffusivities of mass and momentum showed a reasonable agreement with other laboratory-based predictions of turbulent mixing and observational data in atmospheric stably stratified flows.
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