BANG1D: A one-dimensional, lagrangian model of subaqueous turbid surges

BANG1D simulates the mechanics of a subaqueous, turbid surge, a seafloor-failure-induced turbidity current that behaves like a snow avalanche or a pyroclastic burst. BANG1D uses the one-dimensional, layer-averaged equations for the conservation of fluid, sediment, momentum and turbulent kinetic energy in a turbidity current. The Lagrangian forms of these equations are solved explicitly at nodes within the turbid surge as they are tracked moving at discrete time steps across a bathymetric profile. BANG1D simulations compare well with experimental data of turbid flows and with simulations produced by other numerical models. Intermodel comparisons demonstrate the importance of frictional drag at the base of a turbid flow and entrainment across its surface in retarding accelerations induced by fluid pressures and gravity. Sensitivity tests also show that a constraint must be placed on the erosive power of the flow. This is accomplished in BANG1D by coupling the shear velocity at the base of the flow to its turbulent kinetic energy. Use of this coupling results in successful simulations of experimental sediment-laden turbid flows, but not experimental saline flows, which do not carry sediment. This latter finding suggests that additional research is needed into the linkage between frictional drag along a sedimentary boundary and the turbulent kinetic energy in turbid flows.