Numerical Calculation of Turbulent Channel Flow with Porous Ribs

The turbulent flow in a channel with periodic porous ribs on one wall is numerically studied. The numerical model utilizes the Reynolds averaged Navier-Stokes (RANS) equations with a k−ε turbulent model for turbulence closure. Computational results show good agreements with experimental data in flows over a porous rib. The parameter effects, including the pitch ratio PR (1 ∼ 9) and porosity γ (0.4 ∼ 0.6), on flow fields are further examined in detail. Systematic variations of streamline, streamwise and vertical velocities, and turbulent kinetic energy are clearly identified. As to the PR effect, the interaction between outer flow and flow within the cavity is promoted by arranging ribs due to the penetration of the outer flow. Increasing porosity can reduce the downward outer flow by strong flows passing through the porous ribs. The numerical calculations suggest that the flow characteristics for porous ribs are not only a function of the rib geometry, i.e. pitch ratio, but also the porous property, i.e. porosity.