Nonlinear spin-up of a rotating stratified fluid: Experimental method and preliminary results

We consider the nonlinear spin-up of a rotating stratified fluid in a conical container Art analysis of similarity-type solutions to the relevant boundary-layer problem (Duck et al., 1997) has revealed three types of behavior for this geometry. In general, the boundary-layer evolves to either a steady state, a growing boundary-layer, or a finite-time singularity depending art the initial to final rotation rate ratio, and a "modified Burger number." We emphasize the experimental aspects of our continuing spin-up investigations and make some preliminary comparisons with the boundary-layer theory, showing good agreement. The experimental data presented is obtained through particle tracking velocimetry. We briefly discuss the qualitative features of the the spin down experiments which, in general, are dominated by nonaxisymmetric effects. The experiments are performed using a conical container filled with a linearly stratified fluid, the generation of which is nontrivial. We present a general method for creating a linear density profile in containers with sloping boundaries.