Dispersive Force Basis for Concentration Profiles

Abstract

Sediment concentration measurements of particulate slurry flow provide new insights into intense movement of both bed load and suspended load at high concentrations. The submerged weight of the bed-load (contact-load) solids is transferred downward by means of the normal intergranular stress. Associated with this normal stress there is a granular component of the shear stress resisting motion. Only the remaining, fluid-based, component of the shear stress produces the fluid shear velocity which is involved in velocity distribution and other features of turbulent flow. Turbulent support of suspended load entails a dispersive force which can be evaluated on the basis of the usual flux analysis. This force involves a transfer of weight from the particles to the surrounding fluid, which has been measured experimentally. Combined with the inter-granular stresses mentioned above, this dispersive force gives a new method of linking bed-load and suspended-load components to calculate total-load concentration profiles.