On the effect of convection reversal during turbulation of a two-component fluid

Résumé fourni par la source

Unsteady convection in a two-component medium with significantly different transfer coefficients (e. g., in salt water) is theoretically studied. As a specific example, flows arising in a neutrally stratified medium over a flat inclined surface, from which constant (after switching on) heat and admixture fluxes enter the medium, are considered. A well-known exact solution to the unsteady convection problem near a vertical wall with boundary conditions of the second kind is used, which is generalized to the case of a sloping lower boundary. The complete system of hydrothermodynamic and admixture transport equations is reduced to a linear system due to the symmetry of the problem, without any assumptions about the smallness of the perturbation amplitudes. The linearity of the system allows for the use of the superposition principle — independently considering and summing the dynamic effects of the two components of the medium, which determine the deviations in its density. The solution is expressed in terms of repeated probability integrals. The results, in particular, the direction of the resulting flows, depend significantly on the ratio of the exchange coefficients for different substances. For example, nontrivial situations are possible where positive buoyancy influxes nevertheless lead to the emergence of downward currents. Flow turbulence, leading to abrupt changes in effective exchange coefficients, can, in particular, change the direction of convective flows.

Ce résumé expose les affirmations des auteurs. BNTIC ne l’interprète pas comme une validation indépendante des résultats.