Counter-Rotating Quasigeostrophic Ellipsoidal Vortex Pair

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In geophysical flows, coherent vortex structures persist for long time and their interactions dominate the dynamics of geophysical turbulence. Miyazaki et al. derived a Hamiltonian dynamical system describing the interactions of N ellipsoidal vortices, where each coherent vortex was modeled by an ellipsoid of uniform potential vorticity embedded in a locally uniform 3D shear field. In this paper, the interaction of counter-rotating vortex pair (dipole) is investigated. According to the ellipsoidal moment model, the inclination from the vertical axis approaches π/2 and one of the principal axis of the ellipsoid grows exponentially with time, if two slender vortices are placed within a critical distance initially. Direct numerical simulations, based on the Contour Advective Semi-Lagrangian algorithm, are performed in order to assess the validity of the model. The CASL computaion tells that the vortices keep the dipole structure quite robustly. They survive from tilting down by emittimg thin filaments from their top and bottom, even if they are placed very close.
社団法人日本物理学会の論文
2003-08-15