Numerical investigation of double-diffusive convection at vibrations

The problem of convection in a rectangular vertical cell, located in the gravity field and under the action of high-frequency vertical vibrations, is solved using the direct numerical simulation. At the initial moment of time, the system is formed by two horizontal layers of miscible liquids: the lower (heavy) layer is an aqueous solution of sodium chloride, while the upper one is a sugar solution. A two-dimensional formulation is considered; ANSYS Fluent software package is used as a solver. The impermeability and no-slip conditions are satisfied at the cell boundaries. As a result of the difference in the diffusion coefficients of dissolved species, layers with unstable stratification are formed over time near the contact zone. This leads to the onset of convection in the form of thin ascending and descending fingers. The vibrations, on average, lead to a decrease in the growth rate of fingers and the velocity of convection. In the case of relatively high vibrational overloads, a more regular convective structure forms in the diffusion layer leading to a more pronounced mixing of fluids. (paper)