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We present a self-consistent method for deriving moment equations for kinetic models of polymer dynamics. The Doi model [M. Doi, J.Polymer. Sci., Polym. Phys. Ed. 19, 229 (1981)] of liquid-crystalline polymers with the Onsager…

Soft Condensed Matter · Physics 2009-10-31 P. Ilg , I. V. Karlin , H. C. Öttinger

Particle distributions in weakly collisional environments such as the magnetosphere have been observed to show deviations from the Maxwellian distribution. These can often be reproduced in kinetic simulations, but fluid models, which are…

Space Physics · Physics 2018-08-24 Jonathan Ng , Ammar Hakim , Amitava Bhattacharjee

By a further study of the mechanism of the hyperbolic regularization of the moment system for Boltzmann equation proposed in [Z. Cai, Y. Fan, R. Li, Comm. Math. Sci. 11(2): 547-571, 2013], we point out that the key point is treating the…

Mathematical Physics · Physics 2016-02-17 Yuwei Fan , Julian Koellermeier , Jun Li , Ruo Li , Manuel Torrilhon

We examine the dynamics of the Kuramoto model with a new analytical approach. By defining an appropriate set of moments the dynamical equations can be exactly closed. We discuss some applications of the formalism like the existence of an…

Statistical Mechanics · Physics 2009-10-30 C. J. Perez , F. Ritort

Recent works have revealed that matching conditions play a major role on general consistency properties of relativistic fluid dynamics such as causality, stability and wellposedness of the equations of motion. In this paper we derive…

Nuclear Theory · Physics 2021-12-08 Gabriel S. Rocha , Gabriel S. Denicol

New explicit velocity- and position-Verlet-like algorithms of the second order are proposed to integrate the equations of motion in many-body systems. The algorithms are derived on the basis of an extended decomposition scheme at the…

Statistical Mechanics · Physics 2009-11-07 Igor Omelyan , Ihor Mryglod , Reinhard Folk

In the linear random effects model, when distributional assumptions such as normality of the error variables cannot be justified, moments may serve as alternatives to describe relevant distributions in neighborhoods of their means.…

Statistics Theory · Mathematics 2012-03-05 Ping Wu , Winfried Stute , Li-Xing Zhu

Generalising the work of Lenard and Bernstein, we introduce a new, fully relativistic model to describe collisional plasmas. Like the Fokker-Planck operator, this equation represents velocity diffusion and conserves particle number.…

Plasma Physics · Physics 2009-10-23 Adam Noble , David Burton

We use cosmography to present constraints on the kinematics of the Universe, without postulating any underlying theoretical model. To this end, we use a Monte Carlo Markov Chain analysis to perform comparisons to the supernova Ia Union 2…

Cosmology and Nongalactic Astrophysics · Physics 2013-05-30 Alejandro Aviles , Christine Gruber , Orlando Luongo , Hernando Quevedo

We develop a new method for proving hypocoercivity for a large class of linear kinetic equations with only one conservation law. Local mass conservation is assumed at the level of the collision kernel, while transport involves a confining…

Analysis of PDEs · Mathematics 2010-05-11 Jean Dolbeault , Clément Mouhot , Christian Schmeiser

Motivated by the fundamental model of a collisionless plasma, the Vlasov-Maxwell (VM) system, we consider a related, nonlinear system of partial differential equations in one space and one momentum dimension. As little is known regarding…

Analysis of PDEs · Mathematics 2015-09-01 Charles Nguyen , Jennifer Anderson , Stephen Pankavich

Gaussian mixture models are universal approximators in the sense that any smooth density can be approximated arbitrarily well with a Gaussian mixture model with enough components. Due to their broad expressive power, Gaussian mixture models…

Computation · Statistics 2025-02-12 Haley Colgate Kottler , Julia Lindberg , Jose Israel Rodriguez

Shallow Water Moment Equations are reduced-order models for free-surface flows that employ a vertical velocity expansion and derive additional so-called moment equations for the expansion coefficients. Among desirable analytical properties…

Numerical Analysis · Mathematics 2026-04-08 Julian Koellermeier

Numerical schemes that preserve the structure of the kinetic equations can provide stable simulation results over a long time. An electromagnetic particle-in-cell solver for the Vlasov-Maxwell equations that preserves at the discrete level…

Numerical Analysis · Mathematics 2020-02-24 Benedikt Perse , Katharina Kormann , Eric Sonnendrücker

We study a recently derived fully relativistic kinetic model for spin-1/2 particles. Firstly, the full set of conservation laws for energy, momentum and angular momentum are given, together with an expression for the (non-symmetric)…

Plasma Physics · Physics 2019-08-09 R. Ekman , H. Al-Naseri , J. Zamanian , G. Brodin

Equilibrium states in galactic dynamics can be described as stationary solutions of the Vlasov-Poisson system, which is the non-relativistic case, or of the Vlasov-Einstein system, which is the relativistic case. To obtain spherically…

General Relativity and Quantum Cosmology · Physics 2015-06-25 Gerhard Rein , Alan D. Rendall

We present a six-moment multi-fluid model, which solves the governing equations for both ions and electrons, with pressure anisotropy along and perpendicular to the magnetic field direction, as well as the complete set of Maxwell equations.…

Computational Physics · Physics 2019-05-01 Zhenguang Huang , Gabor Toth , Bart van der Holst , Yuxi Chen , Tamas Gombosi

High-resolution simulations of particle-based kinetic plasma models typically require a high number of particles and thus often become computationally intractable. This is exacerbated in multi-query simulations, where the problem depends on…

Numerical Analysis · Mathematics 2023-07-10 Jan S. Hesthaven , Cecilia Pagliantini , Nicolò Ripamonti

This article proposes a highly accurate and conservative method for hyperbolic systems using the finite volume approach. This innovative scheme constructs the intermediate states at the interfaces of the control volumes using the method of…

Numerical Analysis · Mathematics 2023-11-23 Wassim Aboussi , Moussa Ziggaf , Imad Kissami , Mohamed Boubekeur

In this paper, we consider functionals based on moments and non-linear entropies which have a linear growth in time in case of source-type so-lutions to the fast diffusion or porous medium equations, that are also known as Barenblatt…

Analysis of PDEs · Mathematics 2015-01-16 Jean Dolbeault , Giuseppe Toscani