Sand waves in free surface flow : a study with emphasis on hydrodynamic aspects

Abstract

The problem of sand wave generation in free surface flow has been presented and its engineering and scientific significance has been pointed out. A survey of the existing literature on the subject has been performed. The survey concludes with a need for improved understanding of the responsible instability mechanism. An in detail study of depth effects on Helmholtz instability, particularly in layers, leads to a generalised version the classical Kelvinthin fluid of the K-H stability model, which in turn is applied to a free surface flow with bed shear. This model is discussed theoretically and physically. As part of this some qualitative experiments are presented and commented on with a view to the theoretical model. The study shows that the actual K-H model contains several of the basic features of sand wave generation.