On transition process in separated-reattached flows

Abstract

Laminar-to-turbulent transition in shear layer of separated flows is of practical importance. A thorough understanding of transition process is crucial for its prediction and control; to delay the turbulent phase where laminar flow characteristics are desirable or to accelerate it where high mixing and heat transfer rates of turbulent flow are of interest. This paper presents a review of transition process and unsteady behavior of shear layer in separated flows. Despite decades of intensive research in this area the transition process is still not fully understood. However, significant progress has been made with the simulation tools such as Large Eddy Simulation (LES) and Direct Numerical Simulation (DNS). This paper will discuss several important issues such as instability, vortex shedding, coherent structures and so on in separated shear layer transition, trying to provide the current status of understanding and an appraisal of possible future developments.