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Title: Biased diffusion in confined media: Test of the Fick-Jacobs approximation and validity criteria
Author: Burada, Poornachandra Sekhar
Schmid, Gerhard
Reguera, D. (David)
Rubí Capaceti, José Miguel
Hänggi, Peter
Keywords: Sistemes no lineals
Física matemàtica
Nonlinear systems
Mathematical physics
Issue Date: 2007
Publisher: The American Physical Society
Abstract: We study biased, diffusive transport of Brownian particles through narrow, spatially periodic structures in which the motion is constrained in lateral directions. The problem is analyzed under the perspective of the Fick-Jacobs equation, which accounts for the effect of the lateral confinement by introducing an entropic barrier in a one-dimensional diffusion. The validity of this approximation, based on the assumption of an instantaneous equilibration of the particle distribution in the cross section of the structure, is analyzed by comparing the different time scales that characterize the problem. A validity criterion is established in terms of the shape of the structure and of the applied force. It is analytically corroborated and verified by numerical simulations that the critical value of the force up to which this description holds true scales as the square of the periodicity of the structure. The criterion can be visualized by means of a diagram representing the regions where the Fick-Jacobs description becomes inaccurate in terms of the scaled force versus the periodicity of the structure.
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It is part of: Physical Review E, 2007, vol. 75, núm. 5, p. 051111-1-051111-8
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ISSN: 1063-651X
Appears in Collections:Articles publicats en revistes (Física de la Matèria Condensada)

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