Abstract. In a brief survey of the previous work the limitations of the modified Darcy equation and of the vectorial form of the Ergun equation are discussed. To include the effect of wall friction on the flows the viscous resistance term is added to the vectorial form of the Ergun equation. Using the generalized Ergun equation a one-dimensional formulation is presented for flow of fluids through packed beds taking into account the variation of porosity along the radial direction. It is found that there is a reasonable agreement between the numerical and the experimental results and it is observed that the variation of porosity with radial position has greater influence on channeling of velocity near the walls. For the assumption of constant porosity the velocity profiles exhibit similar nature as the plug flow profiles with a thin boundary layer near the wall.

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Abstract. Boundary layer approximation is applied for mixed

Abstract. In the present paper similarity solutions for the convective flow induced by buoyancy in a saturated porous medium adjacent to horizontal impermeable surfaces are obtained. The analysis incorporates the variation of permeability from the wall and expressions for boundary layer thickness, local and overall surface heat-flux are obtained. Applications of the results to convective flows in a geothermal reservoir are discussed.