Large Eddy Simulation of Turbulent Flow Over Fluid-Saturated Porous Media

In this paper, the heat and fluid flow behaviour for a channel partially filled with two different porous blocks and a solid block is investigated numerically using a detailed pore-scale large eddy simulation (LES). Results show that a significant portion of the fluid entering the porous blocks leaks from the porous region to the non-porous region through the porous-fluid interface. Detailed flow patterns visualization inside the porous blocks indicate that the flow leakage leads to the creation of counter-rotating vortex pairs of fluid flow within and above the porous blocks that result in the formation of organized hairpin structures. Investigation of coherent structures show that the legs and the head of hairpins are generated separately by different mechanisms; the legs are produced by flow leakage while the heads are created by vorticity rollup at the shear layer above the porous interface. Finally, results show that the heat transfer mechanisms over the porous media are governed by the formation of organized hairpin structures.