Aller au contenu  Aller au menu  Aller à la recherche

Bienvenue - Laboratoire Jacques-Louis Lions

Print this page |
1) LPPR/retraites : Le Laboratoire Jacques Louis Lions soutient la motion du CoNRS (https://www.cnrs.fr/comitenational/struc_coord/cpcn/motions/200117_Motion_LPPR_vf.pdf) (suite...)

Plusieurs postes ouverts au recrutement au Laboratoire Jacques-Louis Lions

Attention postes au fil de l’eau Date limite de candidature : jeudi 5 mars 2020 à 16h

Lien vers les postes

Chiffres-clé

Chiffres clefs

189 personnes travaillent au LJLL

90 permanents

82 chercheurs et enseignants-chercheurs permanents

8 ingénieurs, techniciens et personnels administratifs

99 personnels non permanents

73 doctorants

14 post-doc et ATER

12 émérites et collaborateurs bénévoles

 

Chiffres mars 2019

 

Séminaire du LJLL - 07 05 2021 14h00 : L. Székelyhidi

07 mai 2021 — 14h00
Exposé à distance retransmis par Zoom
László Székelyhidi (Université de Leipzig)
Magnetohydrodynamic turbulence : weak solutions and conserved quantities
Résumé
The ideal magnetohydrodynamic system in three space dimensions consists of the incompressible Euler equations coupled to the Faraday system via Ohm’s law. This system has a wealth of interesting structure, including three conserved quantities : the total energy, cross-helicity and magnetic helicity. Whilst the former two are analogous (and analytically comparable) to the total kinetic energy for the Euler system, magnetic helicity is known to be more robust and of a different nature. In particular, when studying weak solutions, Onsager-type conditions for all three quantities are known, and are basically on the same level of 1/3-differentiability as the kinetic energy in the ideal hydrodynamic case for the former two. In contrast, magnetic helicity does not require any differentiability, only L^3 integrability. From the physical point of view this difference lies at the heart of the Taylor-Woltjer relaxation theory. From the mathematical point of view it turns out to be closely related to the div-curl structure of the Faraday system. In the talk we present and compare some recent constructions of weak solutions and along the way highlight some of the hidden structures in the ideal magnetohydrodynamic system.
This is joint work with Daniel Faraco and Sauli Lindberg.