##### Department of Mathematics,

University of California San Diego

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### Math 248 - Analysis Seminar

## Michele Coti-Zelati

#### Imperial College

## Vortex axisymmetrization, inviscid damping, and vorticity depletion in the linearized 2D Euler equations

##### Abstract:

We study the 2D Euler equations linearized around smooth, radially symmetric vortices with strictly decreasing vorticity profiles. Under a trivial orthogonality condition, we prove that the perturbation vorticity winds up around the vortex and weakly converges to a radially symmetric configuration, as time goes to infinity. This process is known as ``vortex axisymmetrization'' in the physics literature and is thought to stabilize vortex structures such as hurricanes and cyclones. Additionally, the velocity field converges strongly in L2 to the corresponding equilibrium (as time goes to infinity) and we give optimal decay rates in weighted L2 spaces. Interestingly, the rate of decay is faster for the linearized 2D Euler equations than for the passive scalar equation. The passive scalar rate is degraded by the slow mixing at the vortex core, but the linearized 2D Euler equations expel vorticity from the origin leading to a faster decay rate.

Host: Andrej Zlatos

### January 23, 2018

### 8:45 AM

### AP&M 7321

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