Flow Dynamics Around a Stationary Flat Plate in Proximity to a Free Surface

This work presents a comprehensive experimental investigation of the flow dynamics around a stationary, rigid flat plate positioned close to a free surface. The study employs water tunnel experiments and time-resolved particle image velocimetry (PIV) measurements to explore the interaction between the flat plate and the free surface, considering variations in angles of attack (AOA), Reynolds number (Re), and plate proximity to the free surface. For AOA≤5, when the flat plate is in the vicinity of the free surface, a regular shear layer forms on both sides of the plate, unaffected by the Re. However, for 10≤AOA≤30 and low Re numbers, the shear layer exhibits a jet-like behavior. This jet-like flow extends over the suction side of the plate, and the Coanda effect facilitates its attachment along the plate's surface at various angles of attack. As the Reynolds number increases to intermediate ranges, the shear layer separates from the plate, leading to the formation of shed vortices in the wake. Subsequently, at higher Re numbers, the free surface deformation compels the flow to reattach to the plate. Increasing the submerged height proves effective in eliminating the jet-like flow pattern for different AOAs and Re numbers.