Marc Brachet

Laboratoire de Physique Statistique - Ecole Normale Superieure, Paris

Martes 2/11/2010, 14 hs
Aula Federman, 1er piso, Pabellón I 

The talk is about simulations of finite-temperature superfluids, using the Truncated Gross-Pitaevskii Equation (TGPE). First, we will recall the thermalization that is known to take place in the truncated Euler equation for incompressible fluids. The statistical equilibria of the (conservative) TGPE dynamics will then be characterized using an algorithm based on a stochastically forced Ginzburg-Landau equation (SGLE) that directly generates grand canonical distributions. A standard finite-temperature second-order lambda-transition will be exhibited. A new turbulent mechanism of TGPE thermalization at small scales through a direct cascade of energy will be demonstrated. Dynamical counter-flow effects on vortex evolution will be investigated using SGLE-preparated initial data and a dilatation of vortex rings will be obtained for counter flows larger than their longitudinal velocity.