Double-Diffusive Counterbuoyant Boundary Layer in Laminar Natural Convection

摘要

Double-diffusive counterbuoyant boundary layers may possess the classical self-similar structure only within two distinct and disconnected subdomains of the physical parameter space. In the outer-dominated subdomain, it is the more diffusive (and hence, outermost) of the buoyancy mechanisms which controls the primary direction of flow and the direction of boundar-layer growth, and the converse is true for inner-dominated flows. Between the inner-dominated and outer-dominated domains there lies a still-unexplored domain of nonsimilar flows. Along the similar/nonsimilar borders there are marginal zones of nonuniqueness in which a multiplicity of self-similar solutions may exist. The self-similar subdomains are investigated by several numerical methods (shooting, finite differences, and Picard's method) and by the method of matched asymptotic expansions (at high Prandtl number and/or high Lewis number) in order to demonstrate the above-outlined qualitative features and to map out the borderlines of incipient counterflow. (ERA citation 07:015365)