Passive alteration and control of convective heat transfer utilizing alternate porous cavity-block wafers

Abstract

Passive heat-transfer augmentation or alteration along an external boundary using alternately emplaced porous cavity-block wafers is analyzed in this work. The Brinkman-Forchheimer-extended Darcy Model, which accounts for the effects of impermeable boundary and inertia, is used to characterize the flow field inside the porous region. The present work constitutes an innovative way of altering and control of the flow and heat-transfer characteristics of an external surface. The formulation of the problem shows that flow and heat-transfer characteristics depend on seven dimensionless parameters, namely, the Reynolds number, Darcy number, the Prandtl numbers, inertial parameter, two pertinent geometric parameters, and the number of porous cavity-block obstacles. Solution of the governing equations is carried out using the steam function-vorticity formulation, and an in-depth discussion of the results for various physical interactions between the recirculating flows inside of the cavity and the external flow is presented. Several interesting phenomena such as the interactions between the blowing and displacement effects from the porous blocks and the vortices penetrating into the porous cavities are presented and discussed, and it is shown that altering some parametric values can have significant effects on the external momentum and thermal boundary-layer characteristics. The present investigation forms a pertinent and basic research investigation for altering the skin friction and heat-transfer characteristics of an external surface.