Md. Mamun Molla

Natural convection flow in porous enclosure with localized heating from below with heat flux

Unsteady natural convection flow in a two dimensional fluid saturated porous enclosure with localized heating from below with heat flux, symmetrical cooling from the sides and the insulated top wall has been investigated numerically. The governing equations are the Darcy’s law for the porous media and the energy equation for the temperature field has been considered. The non-dimensional Darcy’s law in terms of the stream function is solved by finite difference method using the successive over-relaxation (SOR) scheme and the energy equation is solved by Alternative Direction Alternative (ADI) scheme. The uniform heat flux source is located centrally at the bottom wall. The numerical results are presented in terms of the streamlines and isotherms, as well as the local and average rate of heat transfer for the wide range of the Darcy’s Rayleigh number and the length of the heat flux source at the bottom wall.

Natural convection of non-Newtonian fluid along a vertical thin cylinder using modified power-law model

A study on the natural convection flow of non-Newtonian fluid along a vertical thin cylinder with constant wall temperature using modified power law viscosity model has been done. The basic equations are transformed to non dimensional boundary layer equations and the resulting systems of nonlinear partial differential equations are then solved employing marching order implicit finite difference method. The evolution of the surface shear stress in terms of local skin-friction, the rate of heat transfer in terms of local Nusselt number, velocity and temperature profiles for shear thinning as well as shear-thickening fluid considering the different values of Prandtl number have been focused. For the Newtonian fluids the present numerical results are compared with available published results which show a good agreement indeed. From the results it can be concluded that, at the leading edge, a Newtonian–like solution exists as the shear rate is not large enough to trigger non-Newtonian effects. Non-Newtonian ef...