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We derive the hydrodynamic limit of a kinetic equation where the interactions in velocity are modelled by a linear operator (Fokker-Planck or Linear Boltzmann) and the force in the Vlasov term is a stochastic process with high amplitude and…

Analysis of PDEs · Mathematics 2020-03-23 Arnaud Debussche , Julien Vovelle

By means of a particle model that includes interactions only via the local particle concentration, we show that hyperballistic diffusion may result. This is done by findng the exact solution of the corresponding non-linear diffusion…

Statistical Mechanics · Physics 2020-12-08 Eirik G. Flekkøy , Alex Hansen , Beatrice Baldelli

We study the dynamics of Brownian particles in a heterogeneous one-dimensional medium with a spatially-dependent diffusion coefficient of the form $D(x)\sim |x|^c$, at constant temperature. The particle's probability distribution function…

Statistical Mechanics · Physics 2016-08-03 Shaked Regev , Niels Grønbech-Jensen , Oded Farago

A possible way to calculate particle spectra as a function of position in pulsar wind nebulae is to solve a Fokker-Planck transport equation. This paper presents numerical solutions to the transport equation with the processes of…

High Energy Astrophysical Phenomena · Physics 2013-09-24 M. J. Vorster , H. Moraal

We consider a population dynamics model coupling cell growth to a diffusion in the space of metabolic phenotypes as it can be obtained from realistic constraints-based modelling. In the asymptotic regime of slow diffusion, that coincides…

Populations and Evolution · Quantitative Biology 2017-02-17 Daniele De Martino , Davide Masoero

General self-consistent expressions for the coefficients of diffusion and dynamical friction in a stable, bound, multicomponent self-gravitating and inhomogeneous system are derived. They account for the detailed dynamics of the colliding…

Astrophysics of Galaxies · Physics 2017-06-20 Jean Heyvaerts , Jean-Baptiste Fouvry , Pierre-Henri Chavanis , Christophe Pichon

In this paper, we address the motion of charged particles subjected to a discrete spectrum of electrostatic waves. We focus on situations when transport dominates, leading to significant variations in particle velocity. Nonetheless, these…

Plasma Physics · Physics 2025-10-23 Didier Bénisti

The problem of a particle diffusion in a fluctuating scalar field is studied. In contrast to most studies of advection diffusion in random fields we analyze the case where the particle position is also coupled to the dynamics of the field.…

Statistical Mechanics · Physics 2011-12-30 David S. Dean , V. Demery

The fractional Fokker-Planck equation, which contains a variable diffusion coefficient, is discussed and solved. It corresponds to the L\'evy flights in a nonhomogeneous medium. For the case with the linear drift, the solution is stationary…

Statistical Mechanics · Physics 2009-06-09 Tomasz Srokowski

It is shown that acceleration of particles in a homogeneous magnetic field that varies periodically with time (Alfven magnetic pumping) reduces to a diffusion of the particles in momentum space; a connection is established between the…

Accelerator Physics · Physics 2018-01-03 M. A. Kutlan

Deriving evolution equations accounting for both anomalous diffusion and reactions is notoriously difficult, even in the simplest cases. In contrast to normal diffusion, reaction kinetics cannot be incorporated into evolution equations…

Statistical Mechanics · Physics 2020-10-23 Sean D Lawley

We describe a formal procedure to obtain and specify the general form of a marginal distribution for the Lagrangian acceleration of fluid particle in developed turbulent flow using Langevin type equation and the assumption that velocity…

Statistical Mechanics · Physics 2007-05-23 A. K. Aringazin , M. I. Mazhitov

We study a stochastic process where an active particle, modeled by a one-dimensional run-and-tumble particle, searches for a target with a finite absorption strength in thermal environments. Solving the Fokker-Planck equation for a uniform…

Statistical Mechanics · Physics 2023-11-09 Byeong Guk Go , Euijin Jeon , Yong Woon Kim

We present a model of diffusion in heterogeneous environment, which qualitatively reflects the transport properties of a polymeric membrane with carbon nanotubes. We derived Fokker-Planck equation from system of stochastic equations,…

Materials Science · Physics 2020-08-19 Ilia Kalashnikov , Polina Likhomanova

Depending on their mechanism of self-propulsion, active particles can exhibit a time-dependent, often periodic, propulsion velocity. The precise propulsion velocity profile determines their mean square displacement and their effective…

Soft Condensed Matter · Physics 2024-05-06 Arnau Jurado Romero , Carles Calero , Rossend Rey

The Fokker--Planck equation describes the evolution of a probability distribution towards equilibrium--the flow parameter is the equilibration time. Assuming the distribution remains normalizable for all times, it is equivalent to an open…

Statistical Mechanics · Physics 2016-09-14 Stam Nicolis , Julien Tranchida , Pascal Thibaudeau

Consider the linear Boltzmann equation of radiative transfer in a half-space, with constant scattering coefficient $\sigma$. Assume that, on the boundary of the half-space, the radiation intensity satisfies the Lambert (i.e. diffuse)…

Analysis of PDEs · Mathematics 2018-09-18 Claude Bardos , François Golse , Iván Moyano

We introduce a fractional Kramers equation for a particle interacting with a thermal heat bath and external non-linear force field. For the force free case the velocity damping follows the Mittag-Leffler relaxation and the diffusion is…

Statistical Mechanics · Physics 2007-05-23 E. Barkai , R. Silbey

We get fractional symmetric Fokker - Planck and Einstein - Smoluchowski kinetic equations, which describe evolution of the systems influenced by stochastic forces distributed with stable probability laws. These equations generalize known…

Statistical Mechanics · Physics 2009-10-31 A. V. Chechkin , V. Yu. Gonchar

We review and complete the existing literature on the kinetic theory of spatially homogeneous systems with long-range interactions taking collective effects into account. The evolution of the system as a whole is described by the…

Statistical Mechanics · Physics 2012-02-20 Pierre-Henri Chavanis