NATURAL CONVECTION IN A HORIZONTAL ANNULAR POROUS CAVITY SATURATED BY A BINARY MIXTURE

摘要

The Darcy model with the Boussinesq approximation is used to study natural convection in a horizontal annular porous layer filled with a binary fluid under the influence of the Soret effect. Both the inner and the outer cylinders are kept at constant temperature with the inner surface higher than that of the outer. The governing parameters for the problem are the Rayleigh number Ra, the Lewis number Le, the buoyancy ratio ψ, the radius ratio of the cavity R, and the normalized porosity e. Two main convective modes are studied, namely, single- and double-cell convection in each half of the enclosure. Numerical solutions of the full governing equations are obtained for a wide range of the governing parameters. The existence of dual solutions for a range of the buoyancy ratio ψ that depends on the other governing parameters has been demonstrated. Also, oscillating flows are obtained on increasing or decreasing ψ beyond critical values.