ABSTRACT
Suspended load is supported by diffusive force in turbulent flow The diffusive force depends on concentration gradient and turbulence intensity. Fine sediment requires smaller diffusive force and coarse sediment requires larger diffusive force to be suspended. Sediment in the layer moves either as suspended load or as bed load. Because turbulent eddies are produced in a zone near the bed, the existence of the hyperconcentrated layer is bound to affect generation and transmission of eddies, and thus changes velocity distribution. The rare hyperconcentrated two-phase flows with pure cohesionless sediment in nature. Hydrotransport of solid materials in pipelines, nevertheless, often involves hyperconcentrated two-phase flow consisting of cohesionless particles. The larger the solid particle and the larger the velocity gradient, the greater the lifting force. The effect of the lifting force is significant near the bed where the velocity gradient and particles concentration is high and negligible in most part of the flow.
