Effect of a circular cylinder and flexible wall on natural convective heat transfer characteristics in a cavity filled with a porous medium

Natural Convective Heat Transfer Characteristics in a cavity filled with a porous medium as related to a solar collector was studied numerically in this investigation. The effect of adding porous medium, obstructed object, and flexible wall on heat transfer performance inside the thermal system was analyzed for different variables such as Rayleigh number, location of the obstructed cylinder, effective thermal conductivity, and the flexibility of the thermal system wall. The transport equations in this study were solved using finite element formulation. In addition, the fluid region was modeled using an Arbitrary-Lagrangian-Eulerian approach coupled with the solid domain. The right vertical wall of the system was assumed flexible while other walls were assumed rigid. The results of this investigation showed that the heat transfer characteristics within the thermal system was enhanced with increasing Rayleigh number and effective thermal conductivity of the porous medium. The location of the obstructed cylinder influenced the average Nusselt number. Placing the cylinder close to the bottom surface was found to achieve optimum heat transfer. The average Nusselt number was found higher for Darcy number compared with Darcy-Forchheimer model for all studied Rayleigh numbers. Further, the results demonstrated in this investigation revealed that using a flexible wall model in the presence of a circular cylinder was not feasible to enhance natural convection heat transfer convection compared with a rigid wall model. Placing obstructed objects inside enclosures are more effective to enhance heat transfer.