DOI: 10.1615/ICHMT.2009.TurbulHeatMassTransf
ISBN Print: 978-1-56700-262-1
ISSN: 2377-2816
An experimental study on turbulence over rib-mounted permeable walls
要約
To discuss and understand the turbulence separation over porous permeable materials, two velocity components of the turbulence fields over rib-mounted porous walls are measured by PIV. A solid (impermeable) or a porous (permeable) square cylinder rib whose hight is a half of the channel height is mounted on the porous bottom wall of fully developed channel flows. The measured bulk flow Reynolds number ranges 103 ≤ Reb ≤ 104. The results indicate that a turbulent recirculation or wake flow region is formed behind the rib at all the measured conditions. In the solid-rib cases, a turbulent separation bubble is formed behind the rib. It becomes smaller at turbulent inflow conditions than at laminar inflow conditions since more part of the entraining fluid is supplied through the permeable bottom wall from the region upstream the rib. In the porous-rib cases, because of the fluid passing through the rib, the recirculation is weakened and shifts downstream. At a laminar inflow condition, the recirculation disappears in the wake flow region behind the rib. Compared with the solid-rib cases, due to the reduced pressure drop by the permeability of the rib, the flow rate through the bottom wall becomes smaller whilst it is comparable to that of the solid-rib case at Reb = 104.