期刊
PHYSICAL REVIEW LETTERS
卷 115, 期 23, 页码 -出版社
AMER PHYSICAL SOC
DOI: 10.1103/PhysRevLett.115.238301
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资金
- Brazilian funding agency FAPEMIG
- Brazilian funding agency CNPq
- Brazilian funding agency CAPES
- Brazilian funding agency CEFET-MG
- Laboratoire 3SR, LabEx Tec 21 (Investissements d'Avenir) [ANR-11-LABX-0030]
In this Letter, we address the relationship between the statistical fluctuations of grain displacements for a full quasistatic plane shear experiment, and the corresponding anomalous diffusion exponent a. We experimentally validate a particular case of the Tsallis-Bukman scaling law, alpha = 2/(3 - q), where q is obtained by fitting the probability density function (PDF) of the displacement fluctuations with a q-Gaussian distribution, and the diffusion exponent is measured independently during the experiment. Applying an original technique, we are able to evince a transition from an anomalous diffusion regime to a Brownian behavior as a function of the length of the strain window used to calculate the displacements of the grains. The outstanding conformity of fitting curves to a massive amount of experimental data shows a clear broadening of the fluctuation PDFs as the length of the strain window decreases, and an increment in the value of the diffusion exponent-anomalous diffusion. Regardless of the size of the strain window considered in the measurements, we show that the Tsallis-Bukman scaling law remains valid, which is the first experimental verification of this relationship for a classical system at different diffusion regimes. We also note that the spatial correlations show marked similarities to the turbulence in fluids, a promising indication that this type of analysis can be used to explore the origins of the macroscopic friction in confined granular materials.
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