Efficient Fourier basis particle simulation

JOURNAL OF COMPUTATIONAL PHYSICS

卷:396

Article

Mitchell, Matthew S.¹  Miecnikowski, Matthew T.¹  Beylkin, Gregory²  Parker, Scott E.¹ 

[1] Univ Colorado, Dept Phys, Boulder, CO 80303 USA

[2] Univ Colorado, Dept Appl Math, Boulder, CO 80303 USA

关键词: Numerical;    Plasma;    Particle-in-cell;    Energy conserving;    Momentum conserving;    Fourier transform;   

DOI  :  10.1016/j.jcp.2019.07.023

来源: Elsevier

【 摘 要 】

The standard particle-in-cell algorithm suffers from grid heating. There exists a gridless alternative which bypasses the deposition step and calculates each Fourier mode of the charge density directly from the particle positions. We show that a gridless method can be computed efficiently through the use of an Unequally Spaced Fast Fourier Transform (USFFT) algorithm. After a spectral field solve, the forces on the particles are calculated via the inverse USFFT (a rapid solution of an approximate linear system) [1,2]. We provide one and two dimensional implementations of this algorithm with an asymptotic runtime of O(N-p + N-m(D) log N-m(D)) for each iteration, identical to the standard PIC algorithm (where N-p is the number of particles, N-m is the number of Fourier modes, and Dis the spatial dimensionality of the problem). We demonstrate superior energy conservation and reduced noise, as well as convergence of the energy conservation at small time steps. (C) 2019 Elsevier Inc. All rights reserved.

【 授权许可】

Free