Turbulence measurements and calculations of stratified shear flows

Turbulence quantities in stably stratified flows were measured with a laser Doppler velocimetry system and a small-size thermocouple. The buoyancy effects on turbulence characteristic quantities, which were velocity fluctuations, eddy viscosities, turbulent Prandtl number, and turbulent heat fluxes, were clarified and the relationships between these quantities and local Richardson number were obtained. A two-equational turbulence model was refined with above experimental results and its validity was investigated by applying it to the stratified flows using characteristic method. In this result, it was found that calculated time-averaged velocity and temperature showed better agreements with experimental ones by using the fined model proposed in this study. (author)