Large-Eddy Simulation of Separated Boundary Layer Transition

Large-eddy simulation has been employed to investigate the mechanisms of separated boundary layer transition under zero and 2.5% free stream turbulence on a flat plate. The geometry is a flat plate with a semi-circular leading edge, which induces a separation bubble at the blend point where the curvature of the surface changes. The simulated results are compared with the available experimental data. The separation bubble at the leading edge is unstable and plays an important role in triggering transition. Data from the simulation have been gathered which allow us to extract all terms in the derived equations for the Reynolds stresses. Aspects of these balances are presented which allow new insights into the physical mechanisms at work.