Prof. Konstantin V. Koshel
Laboratory of geophysical hydrodynamics
Pacific Oceanological Institute
Research interests: Geophysical hydrodynamics. Specific areas of the interests are singular and distributed vortex systems dynamics, chaotic dynamics of the vortex systems, particles' chaotic advection induced by vortex systems, particle clustering in the stochastic velocity fields.
Vortex in deformation background flows: elliptic (Kida vortex), ellipsoidal vortices. Regular and chaotic dynamics.
A brief review on quasi-geostrophic dynamics of an ellipsoidal vortex embedded in a deformation flow in an infinitely deep rotating ocean with a constant buoyancy frequency is presented. The deformation flow incorporates shear, strain and rotational components. Such flows are ubiquitous in geophysical media, such as the ocean and atmosphere. They appear near isolated coherent structures (vortices and jets) and various fixed obstacles (submerged obstacles, continental boundaries). Fluid structures subject to such deformation flows may exhibit drastic changes in motion.
We consider a vortex with an ellipsoidal core with constant vorticity different from the background vorticity value. The core is shown to move along with the flow simultaneously being deformed. Regimes of the core’s behavior depend on the flow characteristics and the initial values of the vortex parameters (the shape and the orientation relative to the flow). These regimes are (i) rotation, (ii) oscillation about either of the two specific directions, and (iii) infinite horizontal elongation of the core.
Given nonstationary periodic external flow, parametric instabilities of the vorticity center and of the vortex dynamics near elliptic points occur. Moreover, the appearance of chaotic dynamics of the vortex becomes possible. Also, we consider fluid particle advection induced
by the vortex including the chaotic advection. Then we consider the influence of turbulent diffusion on the exchange between vortex core and vortex atmosphere. Finally, we assess the potential to determine the depth of the ellipsoidal core from its dynamical imprints on the surface.