Physical theory for near-bed turbulent particle-suspension capacity

The inability to capture the physics of solid-particle suspension in turbulent fluid flow is holding back application of multiphase computational fluid dynamics techniques to the many problems involving particle suspension in nature and society. We present a theory for particle suspension capacity near no-slip frictional boundaries of turbulent flows. The suspension capacity parameter Γ includes universal turbulent flow scales and material properties of the fluid and particles only. Comparison to measurements shows that Γ =1 gives the upper limit of observed suspended particle concentrations in a 10 broad range of flume experiments and field settings. The condition of Γ >1 coincides with complete suppression of coherent turbulent structures near the boundary in Direct Numerical Simulations of sediment-laden turbulent flow. The theory outperforms previous empiric relations when compared to data. It can be applied as a concentration boundary condition in modelling studies of dispersion of particulates in environmental and man-made flows. 15