Laminar boundary layer separation over a fully porous bump

Abstract

This study investigates laminar boundary layer separation over a fully porous Gaussian bump using pore-resolved direct numerical simulations. The bump is formed by randomly packed spheres. Compared to a solid bump, the porous surface significantly alters the flow by enabling cross-bump mass flux. Near-wall fluid is drawn into the bump by favorable pressure gradients on the windward side and exits near the crest and leeward side due to adverse pressure gradients. This pore flow weakens the reverse flow and reduces mean shear in the separated region, delaying reattachment and extending the separation zone. The findings highlight the role of porous structures in modulating boundary layer separation.