Numerical Simulation of a Separating Laminar Boundary Layer Exposed to Ambient Turbulence

Abstract

Laminar separation on wings exposed to flow of a low Reynolds number is a very common phenomenon already at low angles of attack. It is extremely sensitive to turbulence in the freestream as is can affect the boundary layer upstream of the separation, the transition into turbulence and at very large length scales also locally change the angle of attack. Hybrid RANS/LES simulations of laminar separation haven been performed with parametric variations of both intensity and length scale of the ambient turbulence. The boundary layer has then been analyzed in order to demonstrate the effect of eddies impinging the laminar boundary layer upstream of the separation leading to stabilizing and destabilizing effects, which both have been identified and visualized.

Full document