A stochastic spectral subgrid model for the Large Eddy Simulation (LES) of a quasi-geostrophic atmospheric flow is presented, with particular focus on the influence of resolution. The approach of Frederiksen & Kepert  is adopted, where the subgrid scales are represented by a drain-dissipation matrix plus a stochastic backscatter term. Two LES variants are presented: an anisotropic parameterisation, in which the subgrid model is dependent on the zonal and total wavenumbers; and an isotropic parameterisation only dependent on the total wavenumbers. The terms required for the subgrid parameterisations are determined from higher resolution Direct Numerical Simulations (DNSs). Two DNSs are presented, one with 126 zonal and total wavenumbers, and a second with 252 wavenumbers. The LES simulations have half the wavenumbers as compared to the respective DNS data sets. For both resolutions the LES variants agree with the kinetic energy spectra from the DNS very well. As the LES resolution increases the subgrid eddy viscosity and stochastic backscatter both decrease.
|Title of host publication
|17th Australasian Fluid Mechanics Conference 2010
|Number of pages
|Published - 2010
|Australasian Fluid Mechanics Conference 2010 - Auckland New Zealand, Auckland, New Zealand
Duration: 5 Dec 2010 → 9 Dec 2010
Conference number: 17th
|Australasian Fluid Mechanics Conference 2010
|5/12/10 → 9/12/10
|The Australasian Fluid Mechanics Conference has grown steadily from its beginning at the University of Western Australia in 1962. The conference series has traditionally covered the broad field of fluid mechanics in all engineering and scientific disciplines. It provides a forum for presentation of papers in all aspects of fundamental and applied fluid mechanics.
Proceedings of the 17th Australasian Fluid Mechanics Conference 5-9th December 2010 was edited by Prof. G.D. Mallinson and Dr J.E. Cater and published by the Faculty of Engineering in association with the Centre for Continuing Education The University of Auckland.