On the gyrokinetic limit for the two-dimensional Vlasov-Poisson system

We investigate the gyrokinetic limit for the Vlasov-Poisson system in two dimensions, in the regime studied by Golse and Saint-Raymond. We present another proof of convergence to the Euler equation under several assumptions on the energy and on the $L^\infty$ norms of the initial data

Uniqueness for the vortex-wave system when the vorticity is constant near the point vortex

We prove uniqueness for the vortex-wave system with a single point vortex introduced by Marchioro and Pulvirenti in the case where the vorticity is initially constant near the point vortex. Our method relies on the Eulerian approach for this problem and in particular on the formulation in terms of the velocity

Uniqueness and stability for the Vlasov-Poisson system with spatial density in Orlicz spaces

In this paper, we establish uniqueness of the solution of the Vlasov-Poisson system with spatial density belonging to a certain class of Orlicz spaces. This extends the uniqueness result of Loeper (which holds for uniformly bounded density) and the uniqueness result of the second author. Uniqueness is a direct consequence of our main result, which provides a quantitative stability estimate for the Wasserstein distance between two weak solutions with spatial density in such Orlicz spaces, in the spirit of Dobrushin's proof of stability for mean-field PDEs. Our proofs are built on the second-order structure of the underlying characteristic system associated to the equation

Collisions of vortex filament pairs

We consider the problem of collisions of vortex filaments for a model introduced by Klein, Majda and Damodaran, and Zakharov to describe the interaction of almost parallel vortex filaments in three-dimensional fluids. Since the results of Crow examples of collisions are searched as perturbations of antiparallel translating pairs of filaments, with initial perturbations related to the unstable mode of the linearized problem; most results are numerical calculations. In this article we first consider a related model for the evolution of pairs of filaments and we display another type of initial perturbation leading to collision in finite time. Moreover we give numerical evidence that it also leads to collision through the initial model. We finally study the self-similar solutions of the model

Polynomial propagation of moments and global existence for a Vlasov-Poisson system with a point charge

In this paper, we extend to the case of initial data constituted of a Dirac mass plus a bounded density (with finite moments) the theory of Lions and Perthame [6] for the Vlasov-Poisson equation. Our techniques also provide polynomially growing in time estimates for moments of the bounded density.Comment: 27 pages; new version: few typos have been corrected, the introduction has been modifie