Measurements in Buoyancy-Assisting Separated Flow Behind a Vertical Backward-Facing Step

The effect of buoyancy on the flow and the heat-transfer characteristics was investigated experimentally and numerically, using the results of measurements of velocity and temperature distributions in buoyancy-assisting laminar mixed convection boundary layer flow over a vertical two-dimensional heated backward-facing step. As a result of measurements, heat transfer (Nusselt number) and reattachment length behaviors were obtained as a function of the buoyancy level. It was found that an increase in the buoyancy force causes a decrease in the size of the recirculation region behind the step and decreases in the reattachment length. An increase of the buoyancy force also causes the local Nusselt number to increase, and the location of its maximum value to move closer to the step. The results of measurements agreed well with numerical predictions. 14 refs.