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We describe a technique for solving the combined collisionless Boltzmann and Poisson equations in a discretised, or lattice, phase space. The time and the positions and velocities of `particles' take on integer values, and the forces are…

Astrophysics · Physics 2015-06-24 D. Syer , S. Tremaine

The classification of equilibria for the spatially homogeneous Boltzmann equation for Fermi-Dirac particles is proved for any $n$-dimensional velocity space with $n\ge 2$. The same classification has been proven in \cite{Lu2001} for $n=3$.…

Metric Geometry · Mathematics 2022-06-09 Xuguang Lu

We establish an instantaneous smoothing property for decaying solutions on the half-line $(0,+\infty)$ of certain degenerate Hilbert space-valued evolution equations arising in kinetic theory, including in particular the steady Boltzmann…

Analysis of PDEs · Mathematics 2022-03-29 Fedor Nazarov , Kevin Zumbrun

The reaction process $A+B->C$ is modelled for ballistic reactants on an infinite line with particle velocities $v_A=c$ and $v_B=-c$ and initially segregated conditions, i.e. all A particles to the left and all B particles to the right of…

Statistical Mechanics · Physics 2016-08-31 M. J. E. Richardson

Boltzmann's Principle S = k ln W was repeatedly criticized by Einstein since it lacked a proper dynamical foundation in view of the thermal motion of the particles, out of which a physical system consists. This suggests, in particular, that…

Statistical Mechanics · Physics 2013-02-11 E. G. D. Cohen

The hydrodynamic part of the velocity autocorrelation function of a granular fluid in the homogeneous cooling state has been calculated by using mode-coupling theory for a finite system with periodic boundary conditions. The existence of…

Statistical Mechanics · Physics 2015-06-23 J. Javier Brey , M. J. Ruiz-Montero

Using methods of kinetic theory and liquid state theory we propose a description of the non-equilibrium behavior of molecular fluids which takes into account their microscopic structure and thermodynamic properties. The present work…

Statistical Mechanics · Physics 2009-02-24 Umberto Marini Bettolo Marconi , Simone Melchionna

We revisit the dynamics of a black hole accreting energy from a surrounding homogeneous and infinite space. We argue for a simple heuristic modification of the Schwarzschild approximation when the density of the medium is not negligible…

General Relativity and Quantum Cosmology · Physics 2025-11-04 Aurélien Barrau , Killian Martineau , Hanane Zelgoum

Finding reduced models of spatially-distributed chemical reaction networks requires an estimation of which effective dynamics are relevant. We propose a machine learning approach to this coarse graining problem, where a maximum entropy…

Biological Physics · Physics 2018-08-15 Oliver K. Ernst , Thomas Bartol , Terrence Sejnowski , Eric Mjolsness

The extinction time of an isolated population can be exponentially reduced by a periodic modulation of its environment. We investigate this effect using, as an example, a stochastic branching-annihilation process with a time-dependent…

Statistical Mechanics · Physics 2014-08-06 Michael Assaf , Alex Kamenev , Baruch Meerson

We start with some global Maxwellian function $M$, which is a stationary solution (with the constant total density $\rho$) of the Boltzmann equation, and we denote the number of the corresponding space variables by $n$. The notion of…

Mathematical Physics · Physics 2011-06-17 Lev Sakhnovich

We study the dynamics defined by the Boltzmann equation set in the Euclidean space $\mathbb{R}^D$ in the vicinity of global Maxwellians with finite mass. A global Maxwellian is a special solution of the Boltzmann equation for which the…

Analysis of PDEs · Mathematics 2016-08-25 Claude Bardos , Irene M. Gamba , François Golse , C. David Levermore

We consider the non-cutoff Boltzmann equation in the spatially inhomogeneous, soft potentials regime, and establish decay estimates for large velocity. In particular, we prove that pointwise algebraically decaying upper bounds in the…

Analysis of PDEs · Mathematics 2023-11-07 Christopher Henderson , Stanley Snelson , Andrei Tarfulea

Model calculations that include the effects of irreversible, environmental couplings on top of a coupled-channels dynamical description of the collision of two complex nuclei are presented. The Liouville-von Neumann equation for the…

Nuclear Theory · Physics 2009-11-13 Alexis Diaz-Torres , David Hinde , Mahananda Dasgupta , Gerard Milburn , Jeff Tostevin

The initial-boundary value problem for the two-dimensional regular four-velocity discrete Boltzmann system is analyzed in a rectangle. The existence and uniqueness of a classical global positive solution, bounded with its first partial…

Analysis of PDEs · Mathematics 2025-05-20 Koudzo Togbévi Selom Sobah , Amah Séna d'Almeida

In this article we study a fully relativistic model of a two dimensional hard-disk gas. This model avoids the general problems associated with relativistic particle collisions and is therefore an ideal system to study relativistic effects…

Statistical Mechanics · Physics 2009-11-13 Afshin Montakhab , Malihe Ghodrat , Mahmood Barati

We study the effects of inhomogeneities on the evolution of the Universe, by considering a range of cosmological models with discretized matter content. This is done using exact and fully relativistic methods that exploit the symmetries in…

General Relativity and Quantum Cosmology · Physics 2015-06-17 Timothy Clifton , Daniele Gregoris , Kjell Rosquist , Reza Tavakol

We study long time behavior of some nonlinear discrete velocity kinetic equations in the one and three dimensions with periodic boundary conditions. We prove the exponential time decay of solutions towards the global equilibrium in the…

Analysis of PDEs · Mathematics 2025-08-06 Gayrat Toshpulatov

A new kinetic theory Boltzmann-like collision term including correlations is proposed. In equilibrium it yields the one-particle distribution function in the form of a generalised-Lorentzian resembling but not being identical with the…

Plasma Physics · Physics 2009-10-31 R. A. Treumann

Direct Monte Carlo simulations of the Enskog-Boltzmann equation for a spatially uniform system of smooth inelastic spheres are performed. In order to reach a steady state, the particles are assumed to be under the action of an external…

Statistical Mechanics · Physics 2016-08-31 J. M. Montanero , A. Santos