Large scale flow structures and mixing processes in shallow flows

Abstract

Shallow turbulent flows occurring in wide rivers, estuaries, lakes or coastal regions, as well as the atmosphere, are readily susceptible to transverse disturbances that lead to two-dimensional coherent structures, the shallow jet, the shallow wake and the shallow mixing layer are examples of such flow patterns, three types of generation mechanisms are proposed for these flows; namely, topographical forcing, internal transverse shear instabilities, and secondary instabilities of the base flow, the large-scale coherent structures greatly influence the mixing and transport of pollutants that are released into such flows, they may also play an important role in transverse momentum exchange that controls friction in wide channel flows.