The transport of scalar quantities passively advected by velocity fields with a component at small scale l can be modeled at scales larger than l 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 flow at large scales L >> l induces interesting effects on the scalar transport at the meso-scales (i.e. at scales intermediate between l and L). 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. (c) 2006 Elsevier B.V. All rights reserved.

Large-scale effects on meso-scale modeling for scalar transport / M., Cencini; A., Mazzino; S., Musacchio; Vulpiani, Angelo. - In: PHYSICA D-NONLINEAR PHENOMENA. - ISSN 0167-2789. - 220:2(2006), pp. 146-156. [10.1016/j.physd.2006.07.007]

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

VULPIANI, Angelo
2006

Abstract

The transport of scalar quantities passively advected by velocity fields with a component at small scale l can be modeled at scales larger than l 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 flow at large scales L >> l induces interesting effects on the scalar transport at the meso-scales (i.e. at scales intermediate between l and L). 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. (c) 2006 Elsevier B.V. All rights reserved.
2006
multiple-scale analysis; scalar transport; transport modeling
01 Pubblicazione su rivista::01a Articolo in rivista
Large-scale effects on meso-scale modeling for scalar transport / M., Cencini; A., Mazzino; S., Musacchio; Vulpiani, Angelo. - In: PHYSICA D-NONLINEAR PHENOMENA. - ISSN 0167-2789. - 220:2(2006), pp. 146-156. [10.1016/j.physd.2006.07.007]
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11573/85445
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