Flow leakage and Kelvin–Helmholtz instability of turbulent flow over porous media

In the present paper, turbulent flow in a composite porous–fluid system, including permeable surface-mounted bluff body immersed channel flow, is investigated using pore-scale large eddy simulation. The effect of Reynolds number (Re) on leakage from porous to non-porous regions, Kelvin–Helmholtz (K–H) instabilities, as well coherent structures over interface are elaborated by comparing cases with three numbers (Re = 3600, 7200, and 14 400). Results show that more than 52% fluid entering blocks leaks first half region through interface. As Re increases 3600 400, decreases 24%. Flow visualization shows affects size counter-rotating vortex pairs (CRVPs) hairpin above block. At CRVPs larger their centers locate farther away at Y/D ? 0.3 (D two times distance between consecutive pores), while highest 400), they 200% smaller become closer 0.1. Moreover, turbulence statistics reducing number, production delayed downstream; it begins leading edge block (X/D 0), postponed starts nearly middle 4.6). Also, quadrant-hole analysis indicates increasing 400 strengthens sweep events submerses legs into Finally, distribution pressure gradient for confirms occurrence K–H instability vortices For linear growth rate vertical horizontal directions slope 0.136 0.05, respectively. However, direction 33.8%, direction, 200%.