Flow and Heat Transfer Characteristics around A Permeable Porous Obstacle

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Various flow patterns appear in fluid flow over a bluff impermeable body. However, the flow patterns and the flow characteristics around a permeable porous obstacle still remain vague in such fundamental aspects as the interaction between the inner-flow through the porous body and the surrounding outer-flow.An experimental and numerical study has been made on the forced convection around the porous obstacle concentrating on the effect of the porous surface condition. The results show that the effects of porous parameter such as permeability can cause a significant change in flow patterns and suppress the formation of the Karman vortex, and that flow through the porous obstacle is enhanced by an increase in permeability. Here it is also noted that the preferred flow pattern is associated with the reduction of drag force, which depends on the Reynolds number and the blockage ratio of the channel.Moreover, an analytical study has been carried out on the stagnation flow over a porous surface with particular attention to the boundary layer thickness at the stagnation point. The larger permeability of the porous region and the higher Reynolds number yield the reduction of the boundary layer thickness above the permeable interface. In the limit of the permeability k→0, flow behavior coincides with that for the case of the impermeable surface.