Nonhydraulic Effects in Particle‐Driven Gravity Currents in Deep Surroundings

Abstract

In this article, we present an approach to modeling the flow of particle‐driven gravity currents produced by the sudden release of well‐mixed, fixed‐volume suspensions into deep surroundings. Our model accounts for the initial turbulent energy of mixing in the release volume, characteristic of the classical lock–release experiments, as well as the spatiotemporal variability in the driving buoyancy forces attributable to particle settling. We show that, in contrast to compositionally driven flows, particle‐driven flows cannot be described consistently in terms of shallow water theory. Specifically, we show that the presence of particles in the flow dynamics produces significant horizontal velocity shear, thereby changing the flow configuration in important ways from flows assumed to be governed by the shallow water equations. These new flow properties are calculated and contrasted with flow properties derived on the basis of the shallow water equations to show that the shallow water analysis misses dynamical features of the flow. We also show that our model provides significant improvement over the previous shallow water‐based models in predicting the experimentally determined deposition patterns associated with the lock–release experiments.