SPREADING MODEL FOR A TURBIDITY-CURRENT WITH REVERSING BUOYANCY FROM A CONSTANT-VOLUME RELEASE

Particle-laden flows with buoyant interstitial fluid from constant-vol ume releases are often encountered in nature and industry. These curre nts are driven by the excess density of the suspended particles, and a lthough the bulk suspension is negatively buoyant, the buoyant interst itial fluid of the suspension can be detrained through the top of the current. Detrainment of interstitial fluid at the upper interface of t he current and settling of particles through the viscous sublayer at t he bottom of the current are shown to reduce the current spreading rat e to less than that predicted by an inertia-buoyancy balance. simple r elationships are developed for the spreading of such turbidity current s, and these relationships are tested against published laboratory dat a. These results are then compared with a two-dimensional numerical si mulation of the current using a buoyancy-extended k-epsilon turbulence closure scheme.