Structure-preserving methods can be derived for the Vlasov-Maxwell system from a discretisation of the Poisson bracket with compatible finite-elements for the fields and a particle representation of the distribution function. These geometric electromagnetic particle-in-cell (GEMPIC) discretisations feature excellent conservation properties and long-time numerical stability. This paper extends the GEMPIC formulation in curvilinear coordinates to realistic boundary conditions. We build a de Rham sequence based on spline functions with clamped boundaries and apply perfect conductor boundary conditions for the fields and reflecting boundary conditions for the particles. The spatial semi-discretisation forms a discrete Poisson system. Time discretisation is either done by Hamiltonian splitting yielding a semi-explicit Gauss conserving scheme or by a discrete gradient scheme applied to a Poisson splitting yielding a semi-implicit energy-conserving scheme. Our system requires the inversion of the spline finite element mass matrices, which we precondition with the combination of a Jacobi preconditioner and the spectrum of the mass matrices on a periodic tensor product grid.
翻译:对Vlasov-Maxwell系统而言,结构保护方法可以从Poisson 括号的离散中得出,该括号对田间具有相容的有限元素和分布函数的粒子表示。这些细胞中的几何电磁粒子离散具有极好的保护特性和长期数字稳定性。本文将GEMPIC在卷轴坐标上的配方扩展至现实的边界条件。我们根据带有夹紧边界的样条功能,对田间应用完美的导导体边界条件,并反映粒子的边界条件。空间半分解形成一个离散的Poisson系统。时间离散要么由汉密尔顿分解产生半显性盖子保护办法,要么由适用于Poisson分解产生半隐含性节能方案的离散梯度办法进行。我们的系统要求对带有夹线有限元素的质谱质谱质矩阵进行反转,这是将Jacobi前置器和定期抗压产品格中质量矩阵的频谱组合的先决条件。