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Large-scale effects on meso-scale modeling for scalar transport

M. Cencini·A. Mazzino·S. Musacchio·A. Vulpiani
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Abstract

The transport of scalar quantities passively advected by velocity fields with a small-scale component can be modeled at meso-scale level by means of an effective drift and an effective diffusivity, which can be determined by means of multiple-scale techniques. We show that the presence of a weak large-scale flow induces interesting effects on the meso-scale scalar transport. In particular, it gives rise to non-isotropic and non-homogeneous corrections to the meso-scale drift and diffusivity. We discuss an approximation that allows us to retain the second-order effects caused by the large-scale flow. This provides a rather accurate meso-scale modeling for both asymptotic and pre-asymptotic scalar transport properties. Numerical simulations in model flows are used to illustrate the importance of such large-scale effects.

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M. Cencini, A. Mazzino, S. Musacchio, A. Vulpiani. 2005-07-25. Large-scale effects on meso-scale modeling for scalar transport. https://doi.org/10.1016/j.physd.2006.07.007

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