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Diffusion in spatially and temporarily inhomogeneous media

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dc.creator Lehr, Heiner
dc.creator Sagués i Mestre, Francesc
dc.creator Sancho, José M.
dc.date 2011-07-07T12:50:51Z
dc.date 2011-07-07T12:50:51Z
dc.date 1996
dc.date.accessioned 2024-12-16T10:27:18Z
dc.date.available 2024-12-16T10:27:18Z
dc.identifier 1539-3755
dc.identifier http://hdl.handle.net/2445/18700
dc.identifier 114548
dc.identifier.uri http://fima-docencia.ub.edu:8080/xmlui/handle/123456789/22225
dc.description In this paper we consider diffusion of a passive substance C in a temporarily and spatially inhomogeneous two-dimensional medium. As a realization for the latter we choose a phase-separating medium consisting of two substances A and B, whose dynamics is determined by the Cahn-Hilliard equation. Assuming different diffusion coefficients of C in A and B, we find that the variance of the distribution function of the said substance grows less than linearly in time. We derive a simple identity for the variance using a probabilistic ansatz and are then able to identify the interface between A and B as the main cause for this nonlinear dependence. We argue that, finally, for very large times the here temporarily dependent diffusion "constant" goes like t-1/3 to a constant asymptotic value D¿. The latter is calculated approximately by employing the effective-medium approximation and by fitting the simulation data to the said time dependence.
dc.format 9 p.
dc.format application/pdf
dc.language eng
dc.publisher The American Physical Society
dc.relation Reproducció del document publicat a: http://dx.doi.org/10.1103/PhysRevE.54.5028
dc.relation Physical Review e, 1996, vol. 54, num. 5, p. 5028-5036
dc.relation http://dx.doi.org/10.1103/PhysRevE.54.5028
dc.rights (c) The American Physical Society, 1996
dc.rights info:eu-repo/semantics/openAccess
dc.source Articles publicats en revistes (Física Quàntica i Astrofísica)
dc.subject Òptica geomètrica
dc.subject Materials inhomogenis
dc.subject Geometrical optics
dc.subject Inhomogeneous materials
dc.title Diffusion in spatially and temporarily inhomogeneous media
dc.type info:eu-repo/semantics/article
dc.type info:eu-repo/semantics/publishedVersion


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