Numerical Simulation of Separated Flow Transition and Heat Transfer around a Two-Dimensional Rib

摘要

Numerical simulations of separated How transition and heat transfer around a two-dimensional rib mounted in a laminar boundary layer were performed. The separated shear layer becomes unstable due to the Kelvin-Helmholtz instability and generates a two-dimensional vortex. This vortex becomes three-dimensional and collapses in the downstream part of the separation bubble. As a result, transition from laminar to turbulent How occurs in the separated shear layer. Streamwise vortices exist downstream of the reattachment flow region. The low-frequency 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 How region have substantial effects on heat transfer. Downstream of the reattachmenl point, the surface friction coefficient and Nusselt number are different from their profiles in the laminar boundary layer and approach the distributions seen in the turbulent boundary layer.