PASSIVE ALTERATION AND CONTROL OF CONVECTIVE HEAT-TRANSFER UTILIZING ALTERNATE POROUS CAVITY-BLOCK WAFERS

Passive heat-transfer augmentation or alteration along an external bou ndary using alternately emplaced porous cavity-block wafers is analyze d in this work. The Brinkman-Forchheimer-extended Darcy Model, which a ccounts for the effects of impermeable boundary and inertia, is used t o characterize the flow field inside the porous region. The present wo rk constitutes an innovative way of altering and control of the flow a nd heat-transfer characteristics of an external surface. The formulati on of the problem shows that flow and heat-transfer characteristics de pend on seven dimensionless parameters, namely, the Reynolds number, D arcy number, the Prandtl numbers, inertial parameter, two pertinent ge ometric parameters, and the number of porous cavity-block obstacles. S olution of the governing equations is carried out using the steam func tion-vorticity formulation, and an in-depth discussion of the results for various physical interactions between the recirculating flows insi de of the cavity and the external flow is presented. Several interesti ng phenomena such as the interactions between the blowing and displace ment 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 ex ternal momentum and thermal boundary-layer characteristics. The presen t investigation forms a pertinent and basic research investigation for altering the skin friction and heat-transfer characteristics of an ex ternal surface.