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Coarse-grained description of a passive scalar

Antonio Celani·Marco Martins Afonso·Andrea Mazzino
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Abstract

The issue of the parameterization of small-scale dynamics is addressed in the context of passive-scalar turbulence. The basic idea of our strategy is to identify dynamical equations for the coarse-grained scalar dynamics starting from closed equations for two-point statistical indicators. With the aim of performing a fully-analytical study, the Kraichnan advection model is considered. The white-in-time character of the latter model indeed leads to closed equations for the equal-time scalar correlation functions. The classical closure problem however still arises if a standard filtering procedure is applied to those equations in the spirit of the large-eddy-simulation strategy. We show both how to perform exact closures and how to identify the corresponding coarse-grained scalar evolution.

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Antonio Celani, Marco Martins Afonso, Andrea Mazzino. 2006-02-27. Coarse-grained description of a passive scalar. https://doi.org/10.1080/14685240600779388

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