Spin-Up in a Rectangular Cylinder
AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH
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We examined the spin-up from rest of water in a rectangular cylinder. The presence of corners in the cylinder causes the formation of eddies. We found that the number of eddies, as well as eddy size, position, and rotation rate were dependent on the aspect ratio of the cylinder, the depth of the fluid, and the final angular velocity of the cylinder. Two time scales were found to be important in this experiment the traditional Ekman number based on depth, which defines the time scale required for spin-up and an additional Ekman number based on the cylinder length which provides some information about the evolution of the fluid pathlines in route to spin-up. This second Eckman number appears to provide an explanation for both the agreement and disagreement of the experimental results herein and previously published results.
- Fluid Mechanics