Measurements in buoyancy-opposing laminar flow over a vertical forward-facing step

Measurements are reported for buoyancy-opposing laminar mixed convection flow over a vertical, two-dimensional forward-facing step, in which the upstream wall of the step simulated an adiabatic surface, while both the step and the downstream wall from the step were heated to a uniform temperature that was higher than the approaching air temperature. Results presented in this paper are for a step height of 0.8 cm, over a range of free stream velocities 0.39 m s(-1) less than or equal to mu infinity less than or equal to 0.71 m s(-1) and a range of temperature differences 0 degrees C less than or equal to Delta T less than or equal to 35 degrees C between the heated surface and the free stream. Laser-Doppler velocimeter and cold-wire anemometer were used to measure, respectively, the air velocities and the temperature distributions simultaneously. Flow visualizations were also used to observe the nature of the how and to measure the length of the recirculation region downstream of the forward-facing step. The results reveal that the buoyancy-opposing force due to the downstream wall heating affects significantly the velocity and temperature distributions, the local Nusselt number, and the location and the size of the recirculation region downstream of the step.