Non-hydraulic effects in two-layer thermally-enhanced gravity-driven flows

In this article we examine the flow of surface gravity currents having temperature dependent density functions when these currents are subjected to incoming radiation. This radiation leads to a heat source term that, owing to the spatial and temporal variation in upper layer thickness, is itself a function of space and time. This heat source term, in turn, produces a temperature field in the upper layer having non-zero horizontal spatial gradients. These gradients induce shear in the horizontal velocity field thereby ruling out the classic shallow water theory as a viable description for such flows. These new flow properties are calculated and contrasted with flow properties of shallow water theory to show that the shallow water analysis misses dynamical features of the flow. The effects of bottom topography are also included in the model.