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We present a 3D finite element solver for the nonlinear Poisson-Nernst-Planck (PNP) equations for electrodiffusion, coupled to the Stokes system of fluid dynamics. The model serves as a building block for the simulation of macromolecule…

Computational Physics · Physics 2017-04-05 Gregor Mitscha-Baude , Andreas Buttinger-Kreuzhuber , Gerhard Tulzer , Clemens Heitzinger

We propose a numerical method to compute the inertial modes of a container with near-spherical geometry based on the fully spectral discretisation of the angular and radial directions using spherical harmonics and Gegenbauer polynomial…

Fluid Dynamics · Physics 2019-04-11 J. Rekier , A. Trinh , S. A. Triana , V. Dehant

Many problems in physics, chemistry and other fields are perturbative in nature, i.e. differ only slightly from related problems with known solutions. Prominent among these is the eigenvalue perturbation problem, wherein one seeks the…

Mathematical Physics · Physics 2020-03-12 Maseim Kenmoe , Matteo Smerlak , Anton Zadorin

The method of fundamental solutions (MFS), also known as the method of auxiliary sources (MAS), is a well-known computational method for the solution of boundary-value problems. The final solution ("MAS solution") is obtained once we have…

Numerical Analysis · Mathematics 2024-04-12 Georgios D. Kolezas , George Fikioris , John A. Roumeliotis

We study eigenfunctions and eigenvalues of the Dirichlet Laplacian on a bounded domain $\Omega\subset\RR^n$ with piecewise smooth boundary. We bound the distance between an arbitrary parameter $E > 0$ and the spectrum $\{E_j \}$ in terms of…

Analysis of PDEs · Mathematics 2010-06-21 A. H. Barnett , Andrew Hassell

We consider the identification of spatially distributed parameters under $H^1$ regularization. Solving the associated minimization problem by Gauss-Newton iteration results in linearized problems to be solved in each step that can be cast…

Numerical Analysis · Mathematics 2023-08-23 Jan Blechta , Oliver G. Ernst

High-frequency wave propagation is often modelled by nonlinear Friedrichs systems where both the differential equation and the initial data contain the inverse of a small parameter $\varepsilon$, which causes oscillations with wavelengths…

Analysis of PDEs · Mathematics 2024-02-21 Julian Baumstark , Tobias Jahnke

We construct a finite element method for the numerical solution of a fractional porous medium equation on a bounded open Lipschitz polytopal domain $\Omega \subset \mathbb{R}^{d}$, where $d = 2$ or $3$. The pressure in the model is defined…

Numerical Analysis · Mathematics 2025-09-03 José A. Carrillo , Stefano Fronzoni , Endre Süli

There is an extensive literature on magnetic gradient induced spin relaxation. Cates, Schaefer and Happer (CSH) in a seminal paper, have solved the problem in the regime where diffusion theory (the Torrey equation is applicable using an…

Atomic Physics · Physics 2013-05-29 R. Golub , Ryan M. Rohm , C. M. Swank

Multipole expansion methods have been primarily used for analyzing the electromagnetic scattering from non-magnetic isotropic dielectric scatterers, and studies about the scattering from magnetic objects seem to be lacking. In this work, we…

The diffusion limit of the linear Boltzmann equation with a strong magnetic field is performed. The giration period of particles around the magnetic field is assumed to be much smaller than the collision relaxation time which is supposed to…

Analysis of PDEs · Mathematics 2010-05-31 Naoufel Ben Abdallah , Raymond El Hajj

In this paper we investigate a sub-diffusion equation for simulating the anomalous diffusion phenomenon in real physical environment. Based on an equivalent transformation of the original sub-diffusion equation followed by the use of a…

Numerical Analysis · Mathematics 2018-03-29 Zongze Yang , Jungang Wang , Yan Li , Yufeng Nie

We study the expanded mixed finite element method applied to degenerate parabolic equations with the Dirichlet boundary condition. The equation is considered a prototype of the nonlinear Forchheimer equation, a inverted to the nonlinear…

Numerical Analysis · Mathematics 2014-10-01 Akif Ibragimov , Thinh T. Kieu

This paper deals with the deterministic particle method for the equation of porous media (with p = 2). We establish a convergence rate in the Wasserstein-2 distance between the approximate solution of the associated nonlinear transport…

Analysis of PDEs · Mathematics 2025-02-03 Amina Amassad , Datong Zhou

The eigenvalue problem of the Laplace-Beltrami operators on curved surfaces plays an essential role in the convergence analysis of the numerical simulations of some important geometric partial differential equations which involve this…

Numerical Analysis · Computer Science 2013-10-18 Sheng-Gwo Chen , Mei-Hsiu Chi , Jyh-Yang Wu

We present a method for solving the two-dimensional linearized collisionless Boltzmann equation using Fourier expansion along the orbits. It resembles very much solutions present in the literature, but it differs by the fact that everything…

Astrophysics · Physics 2007-05-23 P. Vauterin , H. Dejonghe

The existence of martingale solutions for stochastic porous media equations driven by nonlinear multiplicative space-time white noise is established in spatial dimension one. The Stroock-Varopoulos inequality is identified as a key tool in…

Probability · Mathematics 2024-09-25 Konstantinos Dareiotis , Máté Gerencsér , Benjamin Gess

In this paper, we mainly consider the global solvability of smooth solutions for the Cauchy problem of the three-dimensional Landau-Lifshitz-Slonczewski equation in the Morrey space. We derive the covariant complex Ginzburg-Landau equation…

Analysis of PDEs · Mathematics 2023-07-13 Chenlu Zhang , Huaqiao Wang

We establish pathwise existence of solutions for porous media and fast diffusion equations with nonlinear gradient noise, in the full regime $m\in(0,\infty)$ and for any initial data in $L^2$. Moreover, if the initial data is positive,…

Analysis of PDEs · Mathematics 2023-02-07 Andrea Clini

In this paper a general approach to reconstruct three dimensional field solutions in particle accelerator magnets from distributed magnetic measurements is presented. To exploit the locality of the measurement operation a special…