Onset of Rayleigh–Taylor Convection in a Porous Medium

Abstract

The Rayleigh–Taylor instability and the initial stage of density-driven convection in a porous medium is simulated numerically in reference to geologic problems. A two-layer fluid system in which the lower layer is formed by pure water and the upper layer by an aqueous solution of salts is considered. The upper layer is more dense and viscous. The determination of the characteristic time of the onset of convection in the numerical solution is discussed. The parameters which depend on and do not depend of the initial density fluctuations are revealed. The effect of the viscosity contrast on the onset and development of convection flow and mass transfer is analyzed. The quantitative discrepancies related to neglecting the viscosity contrast in geologic fluids are estimated.