Berlin 2018 – scientific programme
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DY: Fachverband Dynamik und Statistische Physik
DY 60: Anomalous Diffusion (joint session DY/BP)
DY 60.5: Talk
Thursday, March 15, 2018, 11:00–11:15, BH-N 334
Random diffusivity from stochastic equations: two models in comparison for Brownian yet non-Gaussian diffusion. — •Vittoria Sposini1,2, Aleksei V. Chechkin1,3, Flavio Seno4, Gianni Pagnini2, and Ralf Metzler1 — 1Institute for Physics and Astronomy, University of Potsdam, 14476 Potsdam-Golm, Germany — 2Basque Center for Applied Mathematics, 48009 Bilbao, Spain — 3Akhiezer Institute for Theoretical Physics, 61108 Kharkov, Ukraine — 4INFN, Padova Section and Department of Physics and Astronomy 'G.Galilei', University of Padova, 35131 Padova, Italy
Recently a considerable number of systems have been discovered exhibiting a Brownian yet non-Gaussian dynamics, characterised by a linear growth in time of the mean-squared displacement yet a non-Gaussian probability density function of the particle displacement. This behaviour observed in very different physical systems has been interpreted as resulting from diffusion in inhomogeneous environments and mathematically represented through a variability of the diffusion coefficient. Indeed different models describing a fluctuating diffusivity have been studied. Here it is presented a set of stochastic equations describing a time dependent random diffusivity within a broad spectrum of distributions: the class defined as generalised Gamma distribution. Two models for particles spreading in such variable environments are then studied. The first belongs to the class of generalised grey Brownian motion while the second follows from the idea of diffusing diffusivity. We promote these two physical models for the description of stochastic particle motion in complex environments.