PERTURBATION ANALYSIS AND MEASUREMENTS OF BUILDING WAKES IN A STABLY STRATIFIED TURBULENT BOUNDARY-LAYER

Velocity and temperature wakes behind obstacles deeply submerged in a stably stratified turbulent boundary layer with one face perpendicular to the flow direction were investigated using wind-tunnel tests and mathematical analysis. For stably stratified approach flow, the effects of a building wake characterized by momentum deficit are to decrease mean velocity and mean temperature but to increase turbulence intensity and temperature fluctuation intensity. On the other hand, along the centerline of a building wake, mean velocity and mean temperature increase and turbulent intensity and temperature-fluctuation intensity decrease in the presence of longitudinal horseshoe vortices. A perturbation technique for determining the temperature distribution in the wake of an isolated building was developed using momentum and vortex wake arguments. Hunt's theory for velocity distribution in a 'momentum' and 'vortex' wake and a modified method developed by the writers for temperature distributions agreed with measurements of mean velocity and temperature distributions.