title: Energy dissipating structures produced by walls in two-dimensional flows at vanishing viscosity.
abstract: We perform numerical experiments of a dipole crashing into a wall, a generic event in two-dimensional incompressible flows with solid boundaries. The Reynolds number (Re) is varied from 985 to 7880, and no-slip boundary conditions are approximated by Navier boundary conditions with a slip length proportional to Re(-1). Energy dissipation is shown to first set up within a vorticity sheet of thickness proportional to Re(-1) in the neighborhood of the wall, and to continue as this sheet rolls up into a spiral and detaches from the wall. The energy dissipation rate integrated over these regions appears to converge towards Re-independent values, indicating the existence of energy dissipating structures that persist in the vanishing viscosity limit.
authors.affiliation: LMD-CNRS-IPSL, École Normale Supérieure, Paris, France.
authors.forename: Romain
authors.initials: R
authors.lastname: Nguyen van Yen
authors.forename: Marie
authors.initials: M
authors.lastname: Farge
authors.forename: Kai
authors.initials: K
authors.lastname: Schneider