ABSTRACT
Sediment transport, two-phase flow and loose boundary hydraulics are some of the names used to identify problems of interaction between a fluid flow and a granular material mixed into the flow and forming some of the boundaries of the flow which usually change with flow conditions. For convenience, the sediments forming the boundaries of a flow are subdivided into cohesive and non-cohesive sediments, although there is a fairly broad transition range. The initiation or threshold of movement of a particle due to the action of fluid flow is defined as the instant when the applied forces due to fluid drag and lift, causing the particle to move, exceed the stabilizing force due to gravity. The Shields curve applies to uniform sediment at average levels of turbulence. The methods which rely on separation of shear into components due to grain roughness and form drag assume, in principle, that a unique relationship exists between the grain roughness component and total shear.
