摘要
Transition from laminar flow to turbulent flow is of great practical interest as it occurs in many engineering flows and often plays a critical role in aerodynamics and heat transfer performance of those flow devices.There could be many routes through transition,depending on flow configuration,geometry and the way in which transition is initiated by a wide range of possible background disturbances such as free-stream turbulence,pressure gradient,acoustic noise,wall roughness and obstructions,periodic unsteady disturbance and so on.This paper presents a brief overview of wall bounded flow transition in general and focuses more on the transition process in the free shear layer of separation bubbles,demonstrating that at elevated free-stream turbulent intensity the so called bypass transition could occur in geometrically induced separation bubbles where the separation point is fixed.