Steady turbulent density currents on a slope in a rotating fluid

Manucharyan, G.E., Moon, W., Sévellec, F., Wells, A.J., Zhong, J.-Q. and Wettlaufer, J.S. (2014) Steady turbulent density currents on a slope in a rotating fluid. Journal of Fluid Mechanics, 746, 405-436. (doi:10.1017/jfm.2014.119).

Abstract

We consider the dynamics of actively entraining turbulent density currents on a conical sloping surface in a rotating fluid. A theoretical plume model is developed to describe both axisymmetric flow and single-stream currents of finite angular extent. An analytical solution is derived for flow dominated by the initial buoyancy flux and with a constant entrainment ratio, which serves as an attractor for solutions with alternative initial conditions where the initial fluxes of mass and momentum are non-negligible. The solutions indicate that the downslope propagation of the current halts at a critical level where there is purely azimuthal flow, and the boundary layer approximation breaks down. Observations from a set of laboratory experiments are consistent with the dynamics predicted by the model, with the flow approaching a critical level. Interpretation in terms of the theory yields an entrainment coefficient E?1/? where the rotation rate is ?. We also derive a corresponding theory for density currents from a line source of buoyancy on a planar slope. Our theoretical models provide a framework for designing and interpreting laboratory studies of turbulent entrainment in rotating dense flows on slopes and understanding their implications in geophysical flows.

This record has no associated files available for download.

Contributors

Download statistics