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The present study deals with the numerically investigation of developing laminar natural convection in the vertical double-passage porous annuli formed by three vertical concentric cylinders of which the middle cylinder is a thin and perfectly conductive known as baffle. In this analysis, two thermal conditions are considered namely, either inner or outer cylindrical wall is constantly heated while the opposite wall is insulated. An implicit finite difference technique is employed to solve the boundary layer equations in both the annular passages. The temperature profiles and velocity profiles in axial as well as radial directions have been presented for different values of Grashof number, Darcy number, baffle position and radius ratio. The results reveal that both physical and geometrical parameters have profound influence on the development of velocity and thermal fields as well as heat transfer rate.

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The open‐ended vertical double‐passage annular space between three vertical concentric coaxial cylinders is an important physical configuration portraying many practical applications. Hence, in the present analysis, the developing buoyant convection in vertical double‐passage annuli filled with fluid‐saturated porous media is studied numerically by imposing unheated entry and unheated exit thermal boundary conditions. The numerical solutions of the mathematical model equations are found through finite difference technique. The velocity profiles in radial as well as axial directions and temperature profiles have been depicted for vast range of nondimensional numbers, baffle position, and heating and un‐heating ratio. The velocity and thermal gradients decreases as heating section length decreases. Maximum velocity and heat transport occurs in a narrow annular passage rather than equal or wider passages. The presence of porosity causes a reduction in flow velocities and thermal gradients.

In the present analysis, fully developed mixed convection in the vertical double-passage annuli filled with porous media is investigated both analytically and numerically by imposing asymmetric thermal conditions. Three vertical concentric cylinders are used to form double passage annuli of which thin and conductive middle cylinder is considered know as baffle. Using finite difference technique, the governing equations are solved numerically by considering viscous dissipation, whereas the closed form solution are obtained by neglecting viscous dissipation. Numerical solution matches with that of closed form solution in the absence of viscous dissipation. The results reveal that modified Grashof number, Brinkmann number, Darcy number, position of baffle has profound impacts on velocity profiles, temperature profiles and on heat transfer rate.