Separated flow around a flat plate at high incidence: an LES investigation

Abstract

The separated flow past an inclined, nominally two-dimensional flat plate was investigated based on large-eddy simulation. The configuration chosen (Reynolds number Rec = 20 000, angle of attack α = 18°) is similar to a corresponding experimental investigation for airfoils at high angle of attack, which is the final objective. In order to assure reliable results, in a preliminary study the influence of the spanwise extension and the corresponding resolution was examined carefully, leading to the final configuration. The flow field around a flat plate in this range of inclination is dominated by an asymmetric vortex shedding cycle with a Strouhal number St′ ≈ 0.2. A strong vortex develops almost periodically in the vicinity of the trailing edge. The life cycle of this vortex structure controls the entire flow field. At the leeward side of the plate a large clockwise rotating recirculation region of nearly constant pressure exists. A periodically occurring shedding motion of these vortical structures into the wake is not observed.