title: Dissipative flow and vortex shedding in the Painlevé boundary layer of a Bose-Einstein condensate.
abstract: This paper addresses the drag force and formation of vortices in the boundary layer of a Bose-Einstein condensate stirred by a laser beam following the experiments of Phys. Rev. Lett. 83, 2502 (1999)]. We make our analysis in the frame moving at constant speed where the beam is fixed. We find that there is always a drag around the laser beam. We also analyze the mechanism of vortex nucleation. At low velocity, there are no vortices and the drag has its origin in a wakelike phenomenon: This is a particularity of trapped systems since the density gets small in an extended region. The shedding of vortices starts only at a threshold velocity and is responsible for a large increase in drag. This critical velocity for vortex nucleation is lower than the critical velocity computed for the corresponding 2D problem at the center of the cloud.
authors.affiliation: CNRS and Laboratoire Jacques-Louis Lions, Université Paris 6, 175 rue du Chevaleret, 75013 Paris, France.
authors.forename: Amandine
authors.initials: A
authors.lastname: Aftalion
authors.forename: Qiang
authors.initials: Q
authors.lastname: Du
authors.forename: Yves
authors.initials: Y
authors.lastname: Pomeau