On the geometry of solutions of the quasi-geostrophic and Euler equations

Proc Natl Acad Sci U S A. 1997 Nov 25;94(24):12769-70. doi: 10.1073/pnas.94.24.12769.

Abstract

We study solutions of the two-dimensional quasi-geostrophic thermal active scalar equation involving simple hyperbolic saddles. There is a naturally associated notion of simple hyperbolic saddle breakdown. It is proved that such breakdown cannot occur in finite time. At large time, these solutions may grow at most at a quadruple-exponential rate. Analogous results hold for the incompressible three-dimensional Euler equation.