Experimental and analytical investigation of dense gravity currents in a rotating, up-sloping and converging channel

Results are presented from a series of laboratory modelling experiments on dense oceanic outflows, in which the behaviour of dense bottom gravity currents in an inclined, submerged, rotating and convergent vee-shaped channel has been investigated. High-resolution density and velocity profile measurements are presented to demonstrate that the currents are in geostrophic balance along the converging channel section for the full range of parametric conditions investigated. Comparisons with theoretical model predictions based on inviscid rotating hydraulics and Ekman boundary layer dynamics modelling approaches are shown to demonstrate well many qualitative aspects of the hydraulic behaviour of dense bottom gravity currents within such rotating systems. Quantitative discrepancies are ascribed primarily to the omission, in the theoretical analyses, of shear-induced turbulent entrainment and mixing processes. The results demonstrate that the essential dynamics and physical description of the dense water gravity current along the converging, up-sloping channel are well represented by the combined application of the two theoretical modelling approaches adopted.

► Experimental study of dense gravity currents in a rotating, submerged channel. ► Outflows are in geostrophic balance along converging channel topography. ► Ekman and rotating hydraulic models agree well with essential outflow dynamics. ► Quantitative discrepancies arise from model assumptions and simplifications.