On convective instability of the counter propagating fluxes of inter-soluble liquids

Direct 3D numerical modeling of the displacement process of a light liquid by a heavy one in a thin isothermal horizontal layer of finite length has been carried out. Initial non-equilibrium step distribution of liquids density generates convective process in this inhomogeneous system. The effect of liquids miscibility is taken into account over the calculation. The conditions of convection excitation in the regions with unstable stratification near the interface between counter propagating fluxes of liquids have been analyzed. The calculation results of concentration fronts velocity in dependence on densities difference are received in the presence and in the absence of the secondary spiral rollers in a flow. The evolution of secondary convective structures has been simulated in details at various stages of the process. The results of numerical modeling confirm previous experimental data.