Rayleigh-Bénard Convection in Shear Enclosure: The Role of Thermal Instabilities

DNS has been carried out for Rayleigh-Bénard convection for two-dimensional flow in a shear enclosure at fixed Reynolds number of 10,000 and Richardson numbers 0, 25, 50, 75, 87.5, while Prandtl number was fixed as 7.0. The key effect observed was that (apart from the basic vortical flow in an enclosure due to the shearing effects) there was simultaneous induction of buoyancy driven flow in an enclosure due to the convection of heat in the flow. For the cases with low and moderate Richardson number the resulting flow was found to be unperturbed, steady and laminar with an original vortical flow unaltered while for cases with high Richardson numbers the resulting flow was found to be unstable and chaotic in nature that attains a quasi-steady state after a certain period of time with strong bifurcations.