title: Decaying two-dimensional turbulence in a circular container.
abstract: We present direct numerical simulations of two-dimensional decaying turbulence at initial Reynolds number 5 x 10(4) in a circular container with no-slip boundary conditions. Starting with random initial conditions the flow rapidly exhibits self-organization into coherent vortices. We study their formation and the role of the viscous boundary layer on the production and decay of integral quantities. The no-slip wall produces vortices which are injected into the bulk flow and tend to compensate the enstrophy dissipation. The self-organization of the flow is reflected by the transition of the initially Gaussian vorticity probability density function (PDF) towards a distribution with exponential tails. Because of the presence of coherent vortices the pressure PDF become strongly skewed with exponential tails for negative values.
authors.affiliation: LMSNM-CNRS & CMI, Université de Provence, Marseille, France. kschneid@cmi.univ-mrs.fr
authors.forename: Kai
authors.initials: K
authors.lastname: Schneider
authors.forename: Marie
authors.initials: M
authors.lastname: Farge