Laboratory experiments on the tripolar vortex in a rotating fluid

摘要: Within the framework of study coherent vortex structures as emerging in rotating, quasi-two-dimensional flows, tripolar is a relatively novel feature. It consists symmetric, linear arrangement three patches distributed vorticity alternate signs, and axis this configuration rotates about centre core vortex. This paper describes an experimental formation tripole from unstable axisymmetric solidly homogeneous fluid. The flow visualized by addition dye, measured streak photography tracer particles. After digitization, spatial distributions ω stream function ψ are calculated numerically, 'scatter plots’ versus presented for various stages process. Owing to viscous effects (spin-down bottom Ekman layer lateral entrainment ambient fluid) shows exponential decay, both its rotation speed internal, relative flow. comparison observed characteristics with simple point-vortex model reasonable quantitative agreement.