arXiv subjects

R. Brito

Publications and source records attributed to R. Brito.

21 records · Page 2Linked to original sources

arXiv1997

Mesoscopic Theory of Granular Fluids

Using fluctuating hydrodynamics we describe the slow build-up of long range spatial correlations in a freely evolving fluid of inelastic hard spheres. In the incompressible limit, the behavior of spatial velocity correlations (including $r^{-d}$-behavior) is governed by vorticity fluctuations only and agrees well with two-dimensional simulations up to 50 to 100 collisions per particle. The incompressibility assumption breaks down beyond a distance that diverges in the elastic limit.

cond-mat.stat-mech↗

arXiv1997

Patterns and Long Range Correlations in Idealized Granular Flows

An initially homogeneous freely evolving fluid of inelastic hard spheres develops inhomogeneities in the flow field (vortices) and in the density field (clusters), driven by unstable fluctuations. Their spatial correlations, as measured in molecular dynamics simulations, exhibit long range correlations; the mean vortex diameter grows as the square root of time; there occur transitions to macroscopic shearing states, etc. The Cahn--Hilliard theory of spinodal decomposition offers a qualitative understanding and quantitative estimates of the observed phenomena. When intrinsic length scales are of the order of the system size, effects of physical boundaries and periodic boundaries (finite size effects in simulations) are important.

cond-mat.stat-mech↗

arXiv1994

Theoretical approach to two-dimensional traffic flow models

In this paper we present a theoretical analysis of a recently proposed two-dimensional Cellular Automata model for traffic flow in cities with the novel ingredient of turning capability. Numerical simulations of this model show that there is a transition between a freely moving phase with high velocity to a jammed state with low velocity. We study the dynamics of such a model starting with the microscopic evolution equation, which will serve as a basis for further analysis. It is shown that a kinetic approach, based on the Boltzmann assumption, is able to provide a reasonably good description of the jamming transition. We further introduce a space-time continuous phenomenological model leading to a couple of partial differential equations whose preliminary results agree rather well with the numerical simulations.

comp-gas↗