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Center for Nonlinear Studies |
THIS SEMINAR IS PART OF THE CNLS WORKSHOP: NEW DIRECTIONS IN TWO-DIMENSIONAL TURBULENCE BEING HELD AUGUST 28 - SEPTEMBER 1, 2006 AT CNLS.
Laboratory experiments and numerical simulations of 2D turbulence in bounded domains have been carried out to investigate the dynamics of quasi-2D turbulent flows in circular, square and rectangular containers and to quantify the role of large-amplitude vorticity filaments from the boundary layers on the flow evolution. The laboratory experiments have been carried out mostly in stratified fluids, but also in rotating fluids and in shallow fluid layers. The simulations are performed with a 2D Chebyshev spectral method. The dynamics of decaying and forced 2D turbulence in domains bounded by no-slip lateral boundaries is strongly affected by vorticity production nearby the lateral no-slip walls, which is nicely illustrated by the production of boundary-layer vorticity during dipole-wall collisions. The interaction of coherent structures embedded in the 2D turbulence with the lateral no-slip walls results in enhanced vortex production, in the generation of mean rotation of the flow (finally yielding a large central vortex in square domains), in modified energy spectra, in the potential destabilization of the central vortex by the boundary layers, in anisotropy of the turbulence properties as reflected by structure functions and PDFs, etc. In this talk the formation and break-down of large-scale vortices and the anisotropic character of the turbulent flow will be addressed, the vorticity production at no-slip walls will be discussed, and alternative numerical methods for DNS of 2D turbulence in domains with no-slip walls based on the relatively cheap 2D Fourier spectral method will be presented.
Host: Misha Chertkov