DISPERSION IN HEAT AND MASS-TRANSFER NATURAL-CONVECTION ALONG VERTICAL BOUNDARIES IN POROUS-MEDIA

This paper reports an analytical-numerical study on hydrodynamic dispersion in natural convection heat and mass transfer near vertical surfaces embedded in porous media. The study considers the convective flows promoted by the density variation due to the combination of temperature and concentration gradients. Scale analysis is used to determine predominant parameters from a general descriptive form for the diffusive terms in the governing equations. Four classes of flow are possible according to the relative magnitude of the dispersion coefficients. Order of magnitude reasoning is used to obtain the similarity variables and dimensionless parameters, in the search for similarity solutions, An enhanced form of the Runge-Kutta algorithm is applied to solve the system of coupled similarity equations. Results are presented for several cases in each class of flow, covering an extensive range of the governing parameters.