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Related papers: A Phase-Space Approach to Collisionless Stellar Sy…

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We consider fully discrete schemes based on the scalar auxiliary variable (SAV) approach and stabilized SAV approach in time and the Fourier-spectral method in space for the phase field crystal (PFC) equation. Unconditionally energy…

Analysis of PDEs · Mathematics 2019-07-18 Xiaoli Li , Jie Shen

We consider a kinetic model whose evolution is described by a Boltzmann-like equation for the one-particle phase space distribution $f(x,v,t)$. There are hard-sphere collisions between the particles as well as collisions with randomly fixed…

Mathematical Physics · Physics 2020-01-08 Raffaele Esposito , Pedro G. Garrido , Joel L. Lebowitz , Rossana Marra

Assuming the separable augmented density, it is always possible to construct a distribution function of a spherical population with any given density and anisotropy. We consider under what conditions the distribution constructed as such is…

Cosmology and Nongalactic Astrophysics · Physics 2012-04-19 J. An , E. Van Hese , M. Baes

The Vlasov-Poisson system, modeling the evolution of non-collisional plasmas in the electrostatic limit, is approx- imated by a Semi-Lagrangian technique. Spectral methods of periodic type are implemented through a collocation approach.…

Numerical Analysis · Mathematics 2019-03-27 Lorella Fatone , Daniele Funaro , Gianmarco Manzini

The Schr\"odinger Method is a novel approach for modeling numerically self-gravitating, collisionless systems that may have certain advantages over N-body and phase space methods. In particular, smoothing is part of the dynamics and not…

Astrophysics · Physics 2007-05-23 George Davies , Lawrence M. Widrow

We present a numerical study of charged particle motion in a time-independent magnetic field in cylindrical geometry. The magnetic field model consists of an unperturbed reversed-shear helical part and a perturbation consisting of a…

The numerical solution of high dimensional Vlasov equation is usually performed by particle-in-cell (PIC) methods. However, due to the well-known numerical noise, it is challenging to use PIC methods to get a precise description of the…

Numerical Analysis · Mathematics 2015-10-20 Bei Wang , Greg Miller , Phil Colella

In this article, we discuss the stability of soft quasicrystalline phases in a coupled-mode Swift-Hohenberg model for three-component systems, where the characteristic length scales are governed by the positive-definite gradient terms.…

Soft Condensed Matter · Physics 2016-04-20 Kai Jiang , Jiajun Tong , Pingwen Zhang

The current paradigm for understanding galaxy formation in the universe depends on the existence of self-gravitating collisionless dark matter. Modeling such dark matter systems has been a major focus of astrophysicists, with much of that…

Astrophysics of Galaxies · Physics 2015-06-17 Eric I. Barnes , Robert J. Ragan

A geometric numerical method for simulating suspensions of spherical and non-spherical particles with Stokes drag is proposed. The method combines divergence-free matrix-valued radial basis function interpolation of the fluid velocity field…

Computational Physics · Physics 2021-02-26 Benjamin K. Tapley , Helge I. Andersson , Elena Celledoni , Brynjulf Owren

We present a new method to introduce phase-space fluctuations in transport theories, corresponding to a full implementation of the Boltzmann-Langevin equation for fermionic systems. It is based on the procedure originally developed by Bauer…

Nuclear Theory · Physics 2008-11-26 J. Rizzo , Ph. Chomaz , M. Colonna

In this paper we propose and analyze an energy stable numerical scheme for the square phase field crystal (SPFC) equation, a gradient flow modeling crystal dynamics at the atomic scale in space but on diffusive scales in time. In…

Numerical Analysis · Mathematics 2019-10-02 Kelong Cheng , Cheng Wang , Steven M. Wise

On contrary to the customary thought, the well-known ``lemma'' that the distribution function of a collisionless Boltzmann gas keeps invariant along a molecule's path represents not the strength but the weakness of the standard theory. One…

Data Analysis, Statistics and Probability · Physics 2007-05-23 C. Y. Chen

Point processes have broad applications in science and engineering. In physics, their use ranges from quantum chaos to statistical mechanics of many-particle systems. We introduce a spatial form factor (SFF) for the characterization of…

Statistical Mechanics · Physics 2025-05-05 Matteo Massaro , Adolfo del Campo

One of the cornerstones in non--equilibrium statistical mechanics (NESM) is Liouville's theorem, a differential equation for the phase space probability $\rho(q,p; t)$. This is usually derived considering the flow in or out of a given…

Classical Physics · Physics 2016-08-01 Diego González , Sergio Davis

Results are presented of a first study of collisionless magnetic reconnection starting from a recently found exact nonlinear force-free Vlasov-Maxwell equilibrium. The initial state has a Harris sheet magnetic field profile in one direction…

Solar and Stellar Astrophysics · Physics 2016-03-23 Fiona Wilson , Thomas Neukirch , Michael Hesse , Michael G. Harrison , Craig R. Stark

The particle filter (PF) is a powerful inference tool widely used to estimate the filtering distribution in non-linear and/or non-Gaussian problems. To overcome the curse of dimensionality of PF, the block PF (BPF) inserts a blocking step…

Machine Learning · Statistics 2022-03-08 Rui Min , Christelle Garnier , François Septier , John Klein

The ill-posed problem of phase retrieval in optics, using one or more intensity measurements, has a multitude of applications using electromagnetic or matter waves. Many phase retrieval algorithms are computed on pixel arrays using discrete…

Image and Video Processing · Electrical Eng. & Systems 2022-09-21 J. A. Pollock , K. S. Morgan , L. C. P. Croton , M. K. Croughan , G. Ruben , N. Yagi , H. Sekiguchi , M. J. Kitchen

We present a spectral Petrov-Galerkin method for the Boltzmann collision operator. We expand the density distribution $f$ to high order orthogonal polynomials multiplied by a Maxwellian. By that choice, we can approximate on the whole…

Numerical Analysis · Mathematics 2019-03-06 Gerhard Kitzler , Joachim Schöberl

A new phase field crystal (PFC) type theory is presented, which accounts for the full spectrum of solid-liquid-vapor phase transitions within the framework of a single density order parameter. Its equilibrium properties show the most…

Materials Science · Physics 2015-06-23 Gabriel Kocher , Nikolas Provatas