Numerical simulation on steady flow around and through a porous sphere

The flow around and through a porous sphere is investigated numerically. It is found that the recirculating wake existing downstream of the porous sphere is either completely detached from or penetrates it. Specially, in a certain range of Darcy number, the wake may initially increase in size with an increase in Reynolds number but then decrease in size and eventually disappear when the Reynolds number is sufficiently large. For a small Darcy number, the critical Reynolds number for the onset of recirculating wake may be significantly smaller than that of a solid sphere. The present study suggests that the surface curvature has an important effect on the initial position of the onset of recirculating wake.