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|Title:||Diffusion in spatially and temporarily inhomogeneous media|
Sagués i Mestre, Francesc
Sancho, José M.
|Publisher:||The American Physical Society|
|Abstract:||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.|
|Note:||Reproducció del document publicat a: http://dx.doi.org/10.1103/PhysRevE.54.5028|
|It is part of:||Physical Review e, 1996, vol. 54, num. 5, p. 5028-5036|
|Appears in Collections:||Articles publicats en revistes (Ciència dels Materials i Química Física)|
Articles publicats en revistes (Física Quàntica i Astrofísica)
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