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A new method is proposed to numerically extract the diffusivity of a (typically nonlinear) diffusion equation from underlying stochastic particle systems. The proposed strategy requires the system to be in local equilibrium and have…

Statistical Mechanics · Physics 2018-05-09 Peter Embacher , Nicolas Dirr , Johannes Zimmer , Celia Reina

In many-particle diffusions, particles that move the furthest and fastest can play an outsized role in physical phenomena. A theoretical understanding of the behavior of such extreme particles is nascent. A classical model, in the spirit of…

Statistical Mechanics · Physics 2024-11-22 Jacob B. Hass , Aileen N. Carroll-Godfrey , Eric I. Corwin , Ivan Z. Corwin

A driven granular material, e.g. a vibrated box full of sand, is a stationary system which may be very far from equilibrium. The standard equilibrium statistical mechanics is therefore inadequate to describe fluctuations in such a system.…

Statistical Mechanics · Physics 2009-08-12 A. Barrat , A. Puglisi , E. Trizac , P. Visco , F. van Wijland

The photon density operator function is used to calculate light beam propagation through turbulent atmosphere. A kinetic equation for the photon distribution function is derived and solved using the method of characteristics. Optical wave…

Quantum Physics · Physics 2009-11-13 G. P. Berman , A. A. Chumak

Plasma turbulence, and edge density fluctuations in particular, can under certain conditions broaden the cross-section of injected microwave beams significantly. This can be a severe problem for applications relying on well-localized…

In the present study, we perform direct numerical simulations of compressible turbulent boundary layers at the free stream Mach number of 2 ~ 6 laden with dilute phase of spherical particles to investigate the Mach number effects on…

Fluid Dynamics · Physics 2024-11-20 Ming Yu , Lihao Zhao , Xianxu Yuan , Chunxiao Xu

We present a numerical method to deal efficiently with large numbers of particles in incompressible fluids. The interactions between particles and fluid are taken into account by a physically motivated ansatz based on locally defined drag…

Condensed Matter · Physics 2016-08-31 W. Kalthoff , S. Schwarzer , G. H. Ristow , H. J. Herrmann

Motivated by the anomalous diffusion observed in clusters of active Brownian particles (ABPs), where the center-of-mass diffusion coefficient scales as $D\sim N^{-1/2}$ with respect to the number $N$ of particles in the cluster, we derive a…

Statistical Mechanics · Physics 2026-05-07 Daniela Moretti , Pasquale Digregorio , Giuseppe Gonnella , Antonio Suma

Explicit simulations of fluid mixtures of highly size-dispersed particles are constrained by numerical challenges associated with identifying pair-interaction neighbors. Recent algorithmic developments have ameliorated these difficulties to…

Soft Condensed Matter · Physics 2022-12-07 Joseph M. Monti , Gary S. Grest

Using an ensemble of high resolution 2D numerical simulations, we explore the scaling properties of cosmological density fluctuations in the non-linear regime. We study the scaling behaviour of the usual $N$--point volume-averaged…

Astrophysics · Physics 2009-10-30 D. Munshi , L. Y. Chiang , P. Coles , A. L. Melott

Using a density matrix description in space we study the evolution of wavepackets in a fluctuating space-time background. We assume that space-time fluctuations manifest as classical fluctuations of the metric. From the non-relativistic…

General Relativity and Quantum Cosmology · Physics 2010-04-30 E. Göklü , C. Lämmerzahl , A. Camacho , A. Macias

A model for diffusion in liquids that couples the dynamics of tracer particles to a fluctuating Stokes equation for the fluid is investigated in the limit of large Schmidt number. In this limit, the concentration of tracers is shown to…

Statistical Mechanics · Physics 2014-04-03 A. Donev , T. G. Fai , and E. Vanden-Eijnden

In molecular simulation and fluid mechanics, the coupling of a particle domain with a continuum representation of its embedding environment is an ongoing challenge. In this work, we show a novel approach where the latest version of the…

Computational Physics · Physics 2022-12-14 Abbas Gholami , Rupert Klein , Luigi Delle Site

A stochastic model for intermittent fluctuations in the scrape-off layer of magnetically confined plasmas has been constructed based on a super-position of uncorrelated pulses arriving according to a Poisson process. In the most common…

Plasma Physics · Physics 2018-05-04 Audun Theodorsen , Odd Erik Garcia

The dynamics of a one-dimensional stochastic model is studied in presence of an absorbing boundary. The distribution of fluctuations is analytically characterized within the generalized van Kampen expansion, accounting for higher order…

Statistical Mechanics · Physics 2015-05-28 Claudia Cianci , Francesca Di Patti , Duccio Fanelli

We introduce a model of self-propelled particles carrying out a Brownian motion with a diffusion coefficient which depends on the local density of particles within a certain finite radius. Numerical simulations show that in a range of…

Statistical Mechanics · Physics 2009-11-11 Cristobal Lopez

The regularized vacuum fluctuation related to a conformally coupled massless scalar field defined on a space-time with dynamical horizon is computed with respect a radially moving observer in a generic flat Friedmann-Robertson-Walker…

General Relativity and Quantum Cosmology · Physics 2014-04-23 Giovanni Acquaviva , Luca Bonetti , Luciano Vanzo , Sergio Zerbini

Current fluctuations in boundary-driven diffusive systems are, in many cases, studied using hydrodynamic theories. Their predictions are then expected to be valid for currents which scale inversely with the system size. To study this…

Statistical Mechanics · Physics 2016-05-26 Yongjoo Baek , Yariv Kafri , Vivien Lecomte

By combining aspects of the coherent and self intermediate scattering functions, measured by dynamical light scattering on a suspension of hard sphere-like particles, we show that the arrest of particle number density fluctuations spreads…

Soft Condensed Matter · Physics 2015-05-13 W. van Megen , V. A. Martinez , G. Bryant

Fluctuating hydrodynamics based techniques have been developed in recent years for the simulation of Brownian motion of particles. These mesoscale simulation tools are viable approaches for problems where molecular dynamics simulations may…

Fluid Dynamics · Physics 2014-02-11 Yong Chen , Neelesh A. Patankar