Geophysical Fluid Dynamics Laboratory, Univ. of Colorado
In this work we are interested in the effect of a lateral
shear flow A cylinder half filled with water is rotated at rate Omega. When a sphere, initially sitting at mid-depth at the top of the fluid, is withdrawn vertically, a vortical flow is generated by vortex stretching in the area subtended by the sphere. Before the sphere is withdrawn, thermal convection is set up by heating the bottom of the tank. Under suitable external conditions (large enough Omega, weak enough convection), the vortex entirely wipes out the convection occurring under it. Photograph of the experiment. Convection (visualized by Kalliroscopic platelets in the water), with the sphere half immersed. Convection field after the sphere has been withdrawn. Note the absence
of plumes in the fluid (now with differential rotation QT Movie of the Vortex Forming as the Cylinder is Withdrawn (visualization by thymol dye) QT Movie Of The Withdrawal (visualization by Kallirocope) In this research we are carrying out linear and nonlinear stability theory
(to ascertain the parametric dependence of the stabilization), laboratory
experiments (to investigate parameter regions not accessible to theory), and
computational simulations (to quantify the detailed mechanical and thermal
processes leading to linear and nonlinear stabilization). Applications to
atmospheric convection in strong vortices, and to ocean convection in Gulf
Stream Rings and sheared Gulf Stream currents , |