Numerical simulation of separated flow transition and heat transfer around a two-dimensional rib

The present study performs numerical simulations of turbulent flow transition of separated flow and heat transfer around a two-dimensional rib mounted in a laminar boundary layer. The separated shear layer becomes unstable by Kelvin-Helmholtz instability and generates two-dimensional vortex. This vortex becomes three-dimensional and collapses in the latter half of the separation bubble. As a result, transition from laminar to turbulent flow occurs in the separated shear layer. Streamwise vortices exist downstream of the reattachment flow region. Low flapping motion and transition of the separated shear layer are influenced by three-dimensional dynamics upstream of the separation bubble. Large-scale vortices around the reattachment flow region have great effects upon heat transfer. Downstream of the reattachment point, the surface friction coefficient and Nusselt number are different from profiles in the laminar boundary layer, and approach the distributions of the turbulent boundary layer.