Effects of rotation on fronts of density currents

The effects of background rotation with angular velocity f/2 are studied fo r buoyancy driven currents of initial height h(0) whose density exceeds by Delta rho the ambient value of rho(0). Our aim is to find how viscous densi ty currents adjust in time under effects of background rotation focusing on time evolution of fronts of density currents. Rotation reduces the front v elocity, U-F(f) = F(ft)U-F(0), of the density current which is compared to a non-rotating case, U-F(0), by the function F(ft) where F --> 1 as ft --> 0 and F --> 0 as ft --> infinity. When the parameter mu = ft becomes of ord er one, there is a transition to the geostrophic asymptotic regime. We pres ent numerical results for the transition curve for the density current fron t radial position for axisymmetric density currents on a rigid surface in a rotating frame. The transition is from a non-rotating power law to a long- time solution. The results of laboratory experiments are found to agree wit h the results of numerical simulations. (C) 2000 Published by Elsevier Scie nce B.V. All rights reserved.