ABRUPT TRANSITIONS IN HIGH-CONCENTRATION, PARTICLE-DRIVEN GRAVITY CURRENTS

A systematic series of experiments on the instantaneous release of two -dimensional, heavy, particle-driven gravity currents has been conduct ed. High-concentration currents propagated in a qualitatively differen t way than low concentration currents. In particular, beyond a critica l initial volume fraction of particles, the resulting dense current ca me to an abrupt halt at some point down the channel, depositing the bu lk of its initial sediment load as a relativly thick layer of fairly c onstant thickness, characterized by a pronounced, steep snout. A very much thinner layer of sediment extended for some distance beyond the a rrest point. This layer was deposited from the subsequent propagation of a slower moving, low concentration residual cloud. (C) 1998 America n Institute of Physics.