Violation of the Einstein relation in Granular Fluids: the role of correlations

Abstract

We study the linear response in different models of driven granular gases. In some situations, even if the the velocity statistics can be strongly non-Gaussian, we do not observe appreciable violations of the Einstein formula for diffusion versus mobility. The situation changes when strong correlations between velocities and density are present: in this case, although a form of fluctuation-dissipation relation holds, the differential velocity response of a particle and its velocity self-correlation are no more proportional. This happens at high densities and strong inelasticities, but still in the fluid-like (and ergodic) regime.

18 pages, 6 figures, submitted for publication

References in corpus (2)

• The Inelastic Maxwell Model
• Fluctuations of internal energy flow in a vibrated granular gas

Cited by in corpus (17)

• Temperature in and out of equilibrium: a review of concepts, tools and attempts
• The fluctuation-dissipation relation: how does one compare correlation functions and responses?
• Granular Brownian motion
• Fluctuation-Dissipation relation in sub-diffusive systems: the case of granular single-file
• Nonequilibrium Brownian motion beyond the effective temperature
• Dynamical collective memory in fluidized granular materials
• Frequency-dependent fluctuation-dissipation relations in granular gases
• Fast decay of the velocity autocorrelation function in dense shear flow of inelastic hard spheres
• Breakdown of fluctuation-dissipation relations in granular gases
• The Many Faces of Fluctuation-Dissipation Relations Out of Equilibrium
• Tagged active particle: probability distribution in a slowly varying external potential is determined by effective temperature obtained from the Einstein relation
• Fluctuating hydrodynamics for dilute granular gases: a Monte Carlo study
• Rheological effects in the linear response and spontaneous fluctuations of a sheared granular gas
• Mobility and diffusion of intruders in granular suspensions. Einstein relation
• A note on the violation of the Einstein relation in a driven moderately dense granular gas
• Fluctuations in granular gases
• Internal energy fluctuations of a granular gas under steady uniform shear flow