We study the linear response in diff. erent models of driven granular gases. In some situations, even if the velocity statistics can be strongly non-Gaussian, we do not observe appreciable violations of the Einstein formula for diff. usion 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 longer proportional. This happens at high densities and strong inelasticities, but still in the. fluid- like ( and ergodic) regime.
Violation of the Einstein relation in granular fluids: the role of correlations / Puglisi, A; Baldassarri, A; Vulpiani, Angelo. - In: JOURNAL OF STATISTICAL MECHANICS: THEORY AND EXPERIMENT. - ISSN 1742-5468. - 4:(2007), pp. P08016 -1-P08016 -18. [10.1088/1742-5468/2007/08/P08016]
Violation of the Einstein relation in granular fluids: the role of correlations
VULPIANI, Angelo
2007
Abstract
We study the linear response in diff. erent models of driven granular gases. In some situations, even if the velocity statistics can be strongly non-Gaussian, we do not observe appreciable violations of the Einstein formula for diff. usion 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 longer proportional. This happens at high densities and strong inelasticities, but still in the. fluid- like ( and ergodic) regime.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
