Visualization of roll patterns in Rayleigh-Benard convection of air in a rectangular shallow cavity

摘要

Flow visualization is conducted here to study the vortex flow patterns associated with the Rayleigh-Benard con- vection in a horizontal shallow cavity of air. The cavity is a rectangular enclosure characterized by the aspect ratios A_x=16 and A_z=20. Attention is focused on the convection rolls driven at slightly supercritical and subcritical Buoyancies. The results show that at slightly subcritical Ra the induced vortex flow is in the form of rectangular rolls Along the cavity sides and short straight parallel rolls in the cavity core.