Anomalous diffusion in silo drainage |
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Authors: | R Arévalo A Garcimartín D Maza |
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Institution: | (1) Department of Physics and Applied Mathematics, University of Navarra, E-31080 Pamplona, Spain |
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Abstract: | The silo discharge process is studied by molecular
dynamics simulations. The development of the velocity profile and
the probability density function for the displacements in the
horizontal and vertical axis are obtained. The PDFs obtained at
the beginning of the discharge reveal non-Gaussian statistics and
superdiffusive behaviors. When the stationary flow is developed,
the PDFs at shorter temporal scales are non-Gaussian too. For big
orifices a well-defined transition between ballistic and diffusive
regime is observed. In the case of a small outlet orifice, no
well-defined transition is observed. We use a nonlinear diffusion
equation introduced in the framework of non-extensive
thermodynamics in order to describe the movements of the grains.
The solution of this equation gives a well-defined relationship
(γ= 2/(3-q)) between the anomalous diffusion exponent
γ and the entropic parameter q introduced by the
non-extensive formalism to fit the PDF of the fluctuations. |
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Keywords: | 45 70 -n Granular systems 45 70 Mg Granular flow: mixing segregation and stratification 45 50 -j Dynamics and kinematics of a particle and a system of particles |
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