Información del autor
Autor Ernst, M. H. |
Documentos disponibles escritos por este autor (22)
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The solutions of the homogeneous nonlinear Boltzmann equation for inelastic Maxwell models, when driven by different types of thermostats, show, in general, overpopulated high energy tails of the form similar toexp(-ac), with power law tails and[...]texto impreso
The total energy E(t) in a fluid of inelastic particles is dissipated through inelastic collisions. When such systems are prepared in a homogeneous initial state and evolve undriven, E(t) decays initially as t^(?2) ~ exp[?2?? ] (known as Haff's [...]texto impreso
A lattice gas automaton lacks Galilei invariance, and equilibria of systems moving with a finite speed \u --> \ are not simply related by a Galilei transformation to the equilibrium distribution in the rest frame. In the hydrodynamic description[...]texto impreso
We present a generalization of the Green-Kubo expressions for thermal transport coefficients mu in complex fluids of the generic form mu=mu(infinity)+integral(infinity)(0) dtV(-1) (0), i.e. a sum of an instantaneous transp[...]texto impreso
Monte Carlo simulations of the spatially homogeneous Boltzmann equation for inelastic Maxwell molecules, performed by Baldassarri et al. (cond-mat/0111066), have shown that general classes of initial distributions evolve for large times into a s[...]texto impreso
Non-mean-field-type excess correlations at short times are present in three-dimensional (3D) computer simulations of the velocity autocorrelation function, but absent in 1D, 2D, and 4D. They are caused by ring collisions in a quasi-3D slab of si[...]texto impreso
Brito, Ricardo ; Bussemaker, H. J. ; Ernst, M. H. ; Matsui, J. | 1995-09Using analytic and simulation techniques, we study the long-and intermediate-time behavior of the velocity autocorrelation function in two-dimensional lattice gas automata with stationary states that violate detailed balance. Such models are pro[...]texto impreso
Van Noije, T. P. C. ; Ernst, M. H. ; Brito, Ricardo ; García Orza, José Antonio | American Physical Society | 1997-07-21Using fluctuating hydrodynamics we describe the slow buildup 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) be[...]texto impreso
We present generalized Green-Kubo expressions for thermal transport coefficients mu in non-conservative fluid-type systems, of the generic form mu = mu(infinity)+ integral(o)(infinity) dtV(-1) [I-epsilon exp[tL] I](0), where exp[tL] is a pseudo-[...]texto impreso
Spatial fluctuations in dissipative systems, such as rapid granular flows, behave very differently from those in elastic fluids. Fluctuations in the flow field drive the linear and nonlinear instability in the density field (clustering), while v[...]texto impreso
García Orza, José Antonio ; Brito, Ricardo ; Van Noije, T. P. C. ; Ernst, M. H. | 1997-08An initially homogeneous freely evolving fluid of inelastic hard spheres develops inhomogeneities in the dow field u(r, t) (vortices) and in the density held n(r, t) (clusters), driven by unstable fluctuations, delta a = {delta n, delta u}. Thei[...]texto impreso
The majority of lattice gases have, apart from the physical conserved quantities of particle number, momentum and energy, spurious ones, usually staggered in space and time. At the level of linear excitations these staggered modes may be purely [...]texto impreso
FCHC lattice gases are the basic models for studying flow problems in three-dimensional systems. This paper presents a self-contained theoretical analysis and some computer simulations of such lattice gases, extended to include an arbitrary numb[...]texto impreso
The dynamics of inelastic hard spheres is described in terms of the binary collision expansion, yielding the corresponding pseudo-liouville equation and BBGKY hierarchy for the reduced distribution functions. Based on cluster expansion technique[...]texto impreso
The kinetic theory for tagged-particle problems in lattice-gas cellular automata is extended beyond Boltzmann's mean-field approximation by including correlated ring-type collisions. This theory provides explicit expressions for the velocity aut[...]texto impreso
This paper deals with solutions of the nonlinear Boltzmann equation for spatially uniform freely cooling inelastic Maxwell models for large times and for large velocities, and the nonuniform convergence to these limits. We demonstrate how the ve[...]texto impreso
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Van Noije, T. P. C. ; Ernst, M. H. ; Brito, Ricardo | 1998-05The clustering instability in freely evolving granular fluids manifests itself in the density-density correlation function and structure factor. These functions are calculated from fluctuating hydrodynamics. As time increases, the structure fact[...]texto impreso
Grosfils, Patrick ; Boon, Jean-Pierre ; Brito, Ricardo ; Ernst, M. H. | American Physical Society | 1993-10We investigate the space and time behavior of spontaneous thermohydrodynamic fluctuations in a simple fluid modeled by a lattice-gas automaton and develop the statistical-mechanical theory of thermal lattice gases to compute the dynamical struct[...]texto impreso
The complete time dependence of the stress-stress correlation functions in lattice gas cellular automata is calculated from the ring kinetic theory using numerical and analytical methods. This provides corrections, typically of 10-20%, to the us[...]texto impreso
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In this paper we show how, under certain restrictions, the hydrodynamic equations for the freely evolving granular fluid fit within the framework of the time dependent Landau-Ginzburg (LG) models for critical and unstable fluids. The granular fl[...]