Statistical Closure Theory and Subgrid-scale Parameterizations
Jorgen Frederiksen
CSIRO
Abstract
Recent developments in the formulation of turbulence closure theory
for homogeneous and inhomogeneous turbulence and its application to
the subgrid-scale parameterization problem are presented, focussing
on two-dimensional turbulence. Non-Markovian closure models are
compared with ensemble averaged direct numerical simulations (DNS)
for decaying two-dimensional homogeneous turbulence. The application
of the closures for developing subgrid-scale parameterizations of
renormalized viscosity and stochastic backscatter is discussed. Such
parameterizations are needed for large-eddy simulations (LES) in
which simulations are carried out at relatively coarse resolution to
reduce computational costs and focus on the large-scale features of
the flows. Kinetic energy spectra of LES with dynamical subgrid-scale
parameterizations have been found to compare closely with those of
DNS.
The quasi-diagonal direct interaction approximation (QDIA) closure
theory for the interaction of mean flows, inhomogeneous turbulence,
topography and possibly Rossby waves is presented and compared with
DNS on f- and generalized beta- planes. Application of the QDIA
closure to the parameterization of the eddy-topographic force is
discussed.
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