Large-scale structures at various stages of separated boundary layer transition

Large-eddy simulation is employed to investigate separated boundary layer transition induced by a change of curvature of the surface. The geometry is a flat plate with a semi-circular leading edge. The Reynolds number based on the uniform inlet velocity and the leading edge diameter is 3450. The simulated mean and turbulence quantities compare well with the available experimental data. The LES data have been comprehensively analysed to elucidate the transition process leading to breakdown to turbulence. Large-scale structures have been observed at various stage of the transition process. Understanding the formation of these large-scale structures, their evolution and eventual break-up into smaller structures may help to shed light on the transition mechanism.