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We study the entanglement entropy of a random tensor network (RTN) using tools from free probability theory. Random tensor networks are simple toy models that help the understanding of the entanglement behavior of a boundary region in the…

Quantum Physics · Physics 2024-07-04 Khurshed Fitter , Faedi Loulidi , Ion Nechita

The tube model is a central concept in polymer physics, and allows to reduce the complex many-filament problem of an entangled polymer solution to a single filament description. We investigate the probability distribution function of…

Soft Condensed Matter · Physics 2009-08-12 Hauke Hinsch , Erwin Frey

A novel principle is presented which allows for the proof of bounded weak solutions to a class of physically relevant, strongly coupled parabolic systems exhibiting a formal gradient-flow structure. The main feature of these systems is that…

Analysis of PDEs · Mathematics 2015-06-11 Ansgar Jüngel

We present a new algorithm for the identification and physical characterization of current sheets and reconnection sites in 2D and 3D large scale relativisticmagnetohydrodynamic numerical simulations. This has been implemented in the PLUTO…

High Energy Astrophysical Phenomena · Physics 2023-05-29 Matteo Nurisso , Annalisa Celotti , Andrea Mignone , Gianluigi Bodo

Models for collisionless magnetic reconnection in near-Earth space are distinctly characterized as 2D or 3D. In 2D kinetic models, the frozen-in law for the electron fluid is usually broken by laminar dynamics involving structures set by…

This paper is concerned with approximations of the Boltzmann equation based on the method of moments. We propose a generalization of the setting of the moment-closure problem from relative entropy to {\phi}-divergences and a corresponding…

Mathematical Physics · Physics 2015-03-18 M. R. A. Abdel-Malik , E. H. van Brummelen

The molecular density functional theory of fluids provides an exact theory for computing solvation free energies in implicit solvents. One of the reasons it has not received nearly as much attention as quantum density functional theory for…

Statistical Mechanics · Physics 2019-02-04 David M. Rogers

Dynamics of many-particle systems with long-range interaction is collisionless and governed by the Vlasov equation. This dynamics is a flow of a six-dimensional incompressible liquid with uncountable integrals of motion. If the flow…

Statistical Mechanics · Physics 2016-06-22 Victor M. Pergamenshchik

Two-fluid plasma flow equations describe the flow of ions and electrons with different densities, velocities, and pressures. We consider the ideal plasma flow i.e. we ignore viscous, resistive, and collision effects. The resulting system of…

Numerical Analysis · Mathematics 2024-09-25 Jaya Agnihotri , Deepak Bhoriya , Harish Kumar , Praveen Chandrashekhar , Dinshaw S. Balsara

The hierarchy of equations for reduced density matrices that describes a thermodynamically equilibrium quantum system obtained earlier by the author is investigated in the momentum representation. In the paper it is shown that the use of…

Quantum Physics · Physics 2011-05-19 V. A. Golovko

We present new method for studying the equilibrium properties of interacting fluids in an arbitrary external filed. The method is valid in any dimension and it yields an exact results in one dimension. Using this approach, we derive a…

Soft Condensed Matter · Physics 2017-02-17 Benaoumeur Bakhti

Reduced fluid models including electron inertia and ion finite Larmor radius corrections are derived asymptotically, both from fluid basic equations and from a gyrofluid model. They apply to collisionless plasmas with small ion-to-electron…

Plasma Physics · Physics 2022-02-02 Thierry Passot , Pierre-Louis Sulem , Emanuele Tassi

A new method that solves concurrently the multi-fluid and Maxwell's equations has been developed for plasma simulations. By calculating the stress tensor in the multi-fluid momentum equation by means of computational particles moving in a…

Computational Physics · Physics 2018-04-04 Stefano Markidis , Pierre Henri , Giovanni Lapenta , Kjell Ronnmark , Maria Hamrin , Zakaria Meliani , Erwin Laure

We consider the Student-t and Student-r distributions, which maximise Renyi entropy under a covariance condition. We show that they have information-theoretic properties which mirror those of the Gaussian distributions, which maximise…

Probability · Mathematics 2010-08-17 Oliver Johnson , Christophe Vignat

We describe a systematic development of kinetic entropy as a diagnostic in fully kinetic particle-in-cell (PIC) simulations and use it to interpret plasma physics processes in heliospheric, planetary, and astrophysical systems. First, we…

We consider the effect of intermolecular interactions on the optimal size-distribution of $N$ hard spheres that occupy a fixed total volume. When we minimize the free-energy of this system, within the Percus-Yevick approximation, we find…

Soft Condensed Matter · Physics 2009-10-31 Junfang Zhang , Ronald Blaak , Emmanuel Trizac , Jose A. Cuesta , Daan Frenkel

Turbulence may appear as a complex process with a multitude of scales and flow patterns, but still obeys simple physical principles such as the conservation of momentum, of energy, and the maximum entropy principle. The latter states that…

Fluid Dynamics · Physics 2019-04-23 T. -W. Lee

Steady state simulations} of magnetized electron fluid equations with strong anisotropic diffusion based on the first-order hyperbolic approach is carried out using cell-centered higher order upwind schemes, linear and weighted essentially…

Computational Physics · Physics 2019-03-14 Amareshwara Sainadh Chamarthi , Kimiya Komurasaki , Rei Kawashima

This paper presents the state of the art of kinetic modeling techniques for simulating plasma kinetic dynamics in magnetospheres. We describe the critical numerical techniques for enabling large-scale kinetic simulations of magnetospheres:…

Performing accurate large eddy simulations in compressible, turbulent magnetohydrodynamics is more challenging than in non-magnetized fluids due to the complex interplay between kinetic, magnetic and internal energy at different scales.…

Fluid Dynamics · Physics 2019-10-23 Daniele Viganò , Ricard Aguilera-Miret , Carlos Palenzuela