Compositional variation considering diffusion and convection for a binary mixture in a porous medium

In this article we study the compositional variation in a porous cavity having different aspect ratios, accounting for natural convection and for thermal, pressure, and molecular diffusion for a binary mixture. The momentum equation is represented by Darcy's law and is solved numerically together with the energy equation and the species conservation equation using the control-volume scheme. The binary mixture's density and viscosity, as well as molecular, thermal, and pressure diffusion coefficients, vary with temperature, composition, and, pressure. Various thermal boundary conditions are investigated. In the lateral heating case the Soret effect is found to be weak, whereas in the bottom heating condition the Soret effect is more pronounced. Such findings are also evident when both bottom and lateral heating are combined, as ill the third case studied in this article. In the presence of pressure diffusion, the competing effect of the thermal and pressure diffusions objects the compositional variation in the cavity. Darcy number variation also plays all important role in the mixture variation in the cavity, because of the formation of convective cells. It is important to note that the Soret effect is dominant when bottom heating is present and therefore should not be neglected.