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We consider the dynamics of a separable Continuous Time Random Walk (CTRW) when the random walker is biased by a velocity field in a uniformly growing domain. Concrete examples for such domains include growing biological cells or lipid…

Statistical Mechanics · Physics 2020-08-26 F. Le Vot , E. Abad , R. Metzler , S. B. Yuste

We consider the continuous time random walk model (CTRW) of tracer's motion in porous medium flows based on the experimentally determined distributions of pore velocity and pore size reported in Holzner et al. Phys. Rev. E 92, 013015…

Statistical Mechanics · Physics 2017-05-31 Itzhak Fouxon , Markus Holzner

The continuous-time random walk (CTRW) model is useful for alleviating the computational burden of simulating diffusion in actual media. In principle, isotropic CTRW only requires knowledge of the step-size, $P_l$, and waiting-time, $P_t$,…

Statistical Mechanics · Physics 2017-01-19 Shahar Amitai , Raphael Blumenfeld

Based on the theory of continuous time random walks (CTRW), we build the models of characterizing the transitions among anomalous diffusions with different diffusion exponents, often observed in natural world. In the CTRW framework, we take…

Statistical Mechanics · Physics 2018-09-13 Trifce Sandev , Weihua Deng , Pengbo Xu

Continuous Time Random Walks (CTRWs) are jump processes with random waiting times between jumps. We study scaling limits for CTRWs where the distribution of jumps and waiting times is coupled and varies in space and time. Such processes…

Probability · Mathematics 2015-01-06 Peter Straka

The continuous time random walk (CTRW) approach has been widely applied to model large-scale non-Fickian transport in the flow through disordered media. Often, the underlying microscopic transport mechanisms and disorder characteristics are…

Fluid Dynamics · Physics 2024-03-12 Xiangnan Yu , Marco Dentz , HongGuang Sun , Yong Zhang

Standard continuous time random walk (CTRW) models are renewal processes in the sense that at each jump a new, independent pair of jump length and waiting time are chosen. Globally, anomalous diffusion emerges through action of the…

Statistical Mechanics · Physics 2015-06-17 Johannes HP Schulz , Aleksei V Chechkin , Ralf Metzler

Brownian motion is a well-known model for normal diffusion, but not all physical phenomena behave according to a Brownian motion. Many phenomena exhibit irregular diffusive behavior, called anomalous diffusion. Examples of anomalous…

Probability · Mathematics 2011-10-04 Meredith N. Burr

The foundations of the fractional diffusion equation are investigated based on coupled and decoupled continuous time random walks (CTRW). For this aim we find an exact solution of the decoupled CTRW, in terms of an infinite sum of stable…

Statistical Mechanics · Physics 2009-11-07 Eli Barkai

Anomalous transport is usually described either by models of continuous time random walks (CTRW) or, otherwise by fractional Fokker-Planck equations (FFPE). The asymptotic relation between properly scaled CTRW and fractional diffusion…

Statistical Mechanics · Physics 2010-12-09 Bartlomiej Dybiec , Ewa Gudowska-Nowak

We show that, in a broad class of continuous time random walks (CTRW), a small external field can turn diffusion from standard into anomalous. We illustrate our findings in a CTRW with trapping, a prototype of subdiffusion in disordered and…

Disordered Systems and Neural Networks · Physics 2015-06-12 R. Burioni , G. Gradenigo , A. Sarracino , A. Vezzani , A. Vulpiani

We study the dynamics of a radioactive species flowing through a porous material, within the Continuous-Time Random Walk (CTRW) approach to the modelling of stochastic transport processes. Emphasis is given to the case where radioactive…

Statistical Mechanics · Physics 2008-05-17 A. Zoia

Subordinating a random walk to a renewal process yields a continuous time random walk (CTRW) model for diffusion, including the possibility of anomalous diffusion. Transition densities of scaling limits of power law CTRWs have been shown to…

Probability · Mathematics 2010-05-14 Peter Straka , Bruce Ian Henry

A physical-mathematical approach to anomalous diffusion may be based on fractional diffusion equations and related random walk models. The fundamental solutions of these equations can be interpreted as probability densities evolving in time…

Statistical Mechanics · Physics 2008-05-27 Rudolf Gorenflo , Francesco Mainardi

Based on the Langevin description of the Continuous Time Random Walk (CTRW), we consider a generalization of CTRW in which the waiting times between the subsequent jumps are correlated. We discuss the cases of exponential and slowly…

Statistical Mechanics · Physics 2015-05-13 A. V. Chechkin , M. Hofmann , I. M. Sokolov

The well-scaled transition to the diffusion limit in the framework of the theory of continuous-time random walk (CTRW)is presented starting from its representation as an infinite series that points out the subordinated character of the CTRW…

Statistical Mechanics · Physics 2015-06-25 Rudolf Gorenflo , Francesco Mainardi , Alessandro Vivoli

We introduce a heterogeneous continuous time random walk (HCTRW) model as a versatile analytical formalism for studying and modeling diffusion processes in heterogeneous structures, such as porous or disordered media, multiscale or crowded…

Statistical Mechanics · Physics 2018-02-07 Denis S. Grebenkov , Liubov Tupikina

In this article, we generalize the recent Discrete Time Random Walk (DTRW) algorithm, which was introduced for the computation of probability densities of fractional diffusion. Although it has the same computational complexity and shares…

Computational Physics · Physics 2018-08-20 Gurtek Gill , Peter Straka

Functional limit theorem for continuous-time random walks (CTRW) are found in general case of dependent waiting times and jump sizes that are also position dependent. The limiting anomalous diffusion is described in terms of fractional…

Probability · Mathematics 2022-05-03 Vassili N. Kolokoltsov

The combined Continuous Time Random Walk (CTRW) in position and momentum space is introduced, in the form of two coupled integral equations that describe the evolution of the probability distribution for finding a particle at a certain…

Chaotic Dynamics · Physics 2007-10-29 H. Isliker
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