Wake and thermal characteristics for cross-buoyancy mixed convection around and through a porous cylinder

Abstract

The influence of cross buoyancy on the steady flow and mixed convective heat transfer around and through a porous cylinder with internal heat generation is investigated numerically. Based on the Darcy–Brinkman–Forchheimer extended porous medium model, the finite volume method is applied to investigate the wake structure and thermal characteristics in terms of the streamlines, asymmetry of recirculating wakes, temperature distribution, and average Nusselt number. The ranges chosen for the Reynolds number (Re), Darcy number (Da), and Richardson number (Ri) are 5 ≤ Re ≤ 40, 10−6 ≤ Da ≤ 10−2, and 0 ≤ Ri ≤ 1, respectively. For certain ranges above, a pair of asymmetric recirculating wakes is observed, with the upper recirculating wake detached from and the lower one partially penetrating or also detached from the cylinder. The asymmetry of the recirculating wake increases with Ri but decreases with Re. Two or three regimes with the distinct asymmetric characteristics are identified over the range of Da investigated, depending on Re. For the heat transfer performance, cross buoyancy is found to have a certain impeditive impact on the average Nusselt number.