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It is well known that phase function methods allow for the numerical solution of a large class of oscillatory second order linear ordinary differential equations in time independent of frequency. Unfortunately, these methods break down in…

Numerical Analysis · Mathematics 2025-06-04 Richard Chow , James Bremer

In this work we propose a high-order structure-preserving discretization of the cold plasma model which describes the propagation of electromagnetic waves in magnetized plasmas. By utilizing B-Splines Finite Elements Exterior Calculus, we…

Numerical Analysis · Mathematics 2025-01-29 Elena Moral Sánchez , Martin Campos Pinto , Yaman Güçlü , Omar Maj

With the support of hybrid-kinetic simulations and analytic theory, we describe the nonlinear behaviour of long-wavelength non-propagating (NP) modes and fast magnetosonic waves in high-$\beta$ collisionless plasmas, with particular…

High Energy Astrophysical Phenomena · Physics 2023-04-05 Stephen Majeski , Matthew W. Kunz , Jonathan Squire

We consider a class of relaxation problems mixing slow and fast variations which can describe population dynamics models or hyperbolic systems, with varying stiffness (from non-stiff to strongly dissipative), and develop a multi-scale…

Analysis of PDEs · Mathematics 2020-05-27 Philippe Chartier , Mohammed Lemou , Léopold Trémant

Numerical simulation of the complex plasma dynamics associated with high power, high frequency microwave breakdown at high pressures, leading to the formation of filamentary plasma structures such as self-organized plasma arrays, is a…

Plasma Physics · Physics 2025-05-13 Pratik Ghosh , Bhaskar Chaudhury

A new diffuse interface model has been proposed in this study for simulating binary alloy solidification under universal cooling conditions, involving both equilibrium and non-equilibrium solute partitioning. Starting from the Gibbs-Thomson…

Materials Science · Physics 2023-09-22 Chuanqi Zhu , Yusuke Seguchi , Masayuki Okugawa , Yuichiro Koizumi

Motivated by applications to mathematical biology, we study the averaging problem for slow-fast systems, {\em in the case in which the fast dynamics is a stochastic process with multiple invariant measures}. We consider both the case in…

Probability · Mathematics 2023-08-17 B. D. Goddard , M. Ottobre , K. J. Painter , I. Souttar

Spatiotemporal metasurfaces offer unique opportunities for wave manipulation, however, their practical realization is often constrained by the requirement for in-plane spatial modulation, which necessitates a large number of time-varying…

We report an accessible and robust tool for evaluating the effects of Coulomb collisions on a test particle in a plasma that obeys Maxwell-J\"uttner statistics. The implementation is based on the Beliaev-Budker collision integral which…

Plasma Physics · Physics 2018-01-17 Konsta Särkimäki , Eero Hirvijoki , Juuso Terävä

We present a multiscale integrator for Hamiltonian systems with slowly varying quadratic stiff potentials that uses coarse timesteps (analogous to what the impulse method uses for constant quadratic stiff potentials). This method is based…

Numerical Analysis · Mathematics 2011-04-14 Molei Tao , Houman Owhadi , Jerrold E. Marsden

This paper introduces a parallel-in-time algorithm for efficient steady-state solution of the eddy current problem. Its main idea is based on the application of the well-known multi-harmonic (or harmonic balance) approach as the coarse…

Computational Engineering, Finance, and Science · Computer Science 2019-11-07 Iryna Kulchytska-Ruchka , Herbert De Gersem , Sebastian Schöps

Metasurfaces, consisting of large arrays of interacting subwavelength scatterers, pose significant challenges for general-purpose computational methods due to their large electric dimensions and multiscale nature. This paper introduces an…

Computational Physics · Physics 2024-10-07 Emanuele Corsaro , Giovanni Miano , Antonello Tamburrino , Salvatore Ventre , Carlo Forestiere

The high cost of sequential time integration is one major constraint that limits the speedup of a time-parallel algorithm like the Parareal algorithm due to the difficulty of coarsening time steps in a stiff numerical problem. To address…

Computational Physics · Physics 2025-03-06 Weifan Liu

We present {\sc Venice}, an operator splitting algorithm to integrate a numerical model on a hierarchy of timescales. {\sc Venice} allows a wide variety of different physical processes operating a different scales to be coupled on…

Instrumentation and Methods for Astrophysics · Physics 2024-10-30 Maite Wilhelm , Simon Portegies Zwart

The time dependent non-equilibrium radiation diffusion equations are important for solving the transport of energy through radiation in optically thick regimes and find applications in several fields including astrophysics and inertial…

Numerical Analysis · Mathematics 2014-03-05 Bobby Philip , Zhen Wang , Mark Berrill , Manuel Rodriguez Rodriguez , Michael Pernice

In this paper, we propose, analyze, and test an efficient algorithm for computing ensemble average of incompressible magnetohydrodynamics (MHD) flows, where instances/members correspond to varying kinematic viscosity, magnetic diffusivity,…

Numerical Analysis · Mathematics 2021-08-12 Muhammad Mohebujjaman , Hongwei Wang , Leo G. Rebholz , Md. Abdullah Al Mahbub

Dynamic inverse problems are challenging to solve due to the need to identify and incorporate appropriate regularization in both space and time. Moreover, the very large scale nature of such problems in practice presents an enormous…

Numerical Analysis · Mathematics 2025-01-23 Toluwani Okunola , Mirjeta Pasha , Misha Kilmer , Melina Freitag

We are interested in numerically solving a transitional model derived from the Bloch model. The Bloch equation describes the time evolution of the density matrix of a quantum system forced by an electromagnetic wave. In a high frequency and…

Analysis of PDEs · Mathematics 2023-08-02 Brigitte Bidégaray-Fesquet , Clément Jourdana , Léopold Trémant

We study two mixed robust/average-case submodular partitioning problems that we collectively call Submodular Partitioning. These problems generalize both purely robust instances of the problem (namely max-min submodular fair allocation…

Data Structures and Algorithms · Computer Science 2016-08-17 Kai Wei , Rishabh Iyer , Shengjie Wang , Wenruo Bai , Jeff Bilmes

In this paper, we propose a hybrid parallel programming approach for a numerical solution of a two-dimensional acoustic wave equation using an implicit difference scheme for a single computer. The calculations are carried out in an implicit…

Computational Physics · Physics 2020-06-19 Arshyn Altybay , Michael Ruzhansky , Niyaz Tokmagambetov