Abstract:
We present a mainly theoretical study of high-Reynolds-number planar gravity
currents in a uniformly flowing deep ambient. The gravity currents are generated by a
constant line source of fluid, and may also be supplied with a source of horizontal
momentum and a source of particles. We model the motion using a shallow-water
approximation and represent the effects of the ambient flow by imposing a Froude
-number condition in a moving frame. We present analytic and numerical expressions
for the threshold ambient flow speed above which no upstream propagation can occur
at longtime. For homogeneous gravity currents in an ambient flow below threshold,
we find similarity solutions in which the up- and downstream fronts spread at a
constant rate and the current propagates indefinitely in both directions. For gravity
currents consistingofbothinterstitial fluid of a different density to the ambient and
sediment in gparticle load, we find long-time asymptotic solutions for ambient flow
strengths below threshold
