CHAPTER I - Introduction to the Problems of Flow Separation

Abstract

This chapter provides an overview of the problems of flow separation. The problem of flow separation is, perhaps, one of the most important hydrodynamic problems to be investigated intensively to find its solution satisfactorily. Because of the complexity of the problem, a rigorous definition of flow separation and stall should be made. The classical concept of flow separation is because of viscosity; therefore, it is often expressed as boundary layer flow separation or boundary layer separation. The chapter highlights classical concept of flow separation is outlined and then the generalized definition of flow separation. The problem of flow separation is as old as that of boundary layer theory. Ludwig Prandtl, the father of the boundary layer concept, was concerned about flow separation before he started his work on the boundary layer. The chapter highlights multiple instabilities of the overall flow field and of various subfields. As Reynolds number increases, the resulting unsteady, three-dimensional, and interacting vortical patterns become keys to some of the perplexing experimental observations reported by various investigators.