Particle-laden flows with buoyant interstitial fluid from constant-volume releases are often encountered in nature and industry. These currents are driven by the excess density of the suspended particles, and although the bulk suspension is negatively buoyant, the buoyant interstitial fluid of the suspension can be detrained through the top of the current. Detrainment of interstitial fluid at the upper interface of the current and settling of particles through the viscous sublayer at the bottom of the current are shown to reduce the current spreading rate to less than that predicted by an inertia-buoyancy balance. Simple relationships are developed for the spreading of such turbidity currents, and these relationships are tested against published laboratory data. These results are then compared with a two-dimensional numerical simulation of the current using a buoyancy-extended k - ε turbulence closure scheme.

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