2D-DNS of Quasi-2D Turbulence in Shallow Water
DELFT UNIV OF TECHNOLOGY (NETHERLANDS)J M BURGERS CENTRE
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Through a series of cases, we investigate the possibilities of the shallow-water solver Delft3D-Flow of simulating the evolution of quasi-2D turbulence in shallow water subjected to internal and external friction and forcing. This paper presents the simplest case, namely the 2D-DNS of laboratory experiments of freely-evolving 2D turbulence, initiated by a rake in a shallow fresh-water layer on top of a salt-water layer in a square 1 1 m2 basin Maassen 2000. Tabeling et al. 1991 report similar experiments in a fluid with a free surface but initiated by vortices counter-rotating in a chessboard arrangement. Likewise, our depth-averaged free-surface simulations are initiated by random as well as by chessboard vortices. We compare the temporal evolution of the simulated vorticity field in a viscous fluid with observations as well as with simulations of Clercx et al. 1999 dedicated to incompressible 2D turbulence simulation with a rigid lid. Theirs and our simulations agree with the experimentally observed evolution of vorticity into just two vortices with opposite rotation. All simulations neglect the friction at the density interface and exhibit lesser decay of kinetic energy than observed in the experiments of Maassen 2000.
- Fluid Mechanics
- Numerical Mathematics