Rheology of Hyperconcentrations

A physically based quadratic rheological model for hyperconcentrated flows is tested with experimental data sets. The model includes components describing: (1) Cohesion between particles; (2) viscous friction between fluid and sediment particles; (3) impact of particles; and (4) turbulence. The resulting quadratic formulation of the shear stress is shown to be in excellent agreement with the experimental data sets of Bagnold, Savage and McKeown, and Govier et al. When the quadratic model is written in a linearized dimensionless form, the ratio D* of dispersive to viscous stresses is shown to play a dominant role in the rheology of hyperconcentrations. The quadratic model is best suited when (30 < D* < 400). At low values of D*, the quadratic model reduces to the simple Bingham plastic model (D* < 30), and at large values of D*, a turbulent-dispersive model is indicated (D* > 400).