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arXiv 2205.04448math.NAastro-ph.SRcs.NA
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球对称Euler-泊松方程的能量守恒和平衡间断Galerkin方法

Energy conserving and well-balanced discontinuous Galerkin methods for the Euler-Poisson equations in spherical symmetry

Weijie Zhang, Yulong Xing, Eirik Endeve

摘要:

本文提出了求解球对称Euler-泊松方程的高阶Runge-Kutta(RK)间断Galerkin方法。该方案可以保持一般多变的平衡态,并实现总能量守恒的机器精度精心设计的空间和时间离散。为了达到良好平衡的性质,数值解被分解为平衡和波动分量,这是不同的处理在源项近似。在该过程中遇到的一个重要挑战是平衡态的复杂性,其由Lane-Emden方程控制。对于总能量守恒,我们提出了二阶和三阶RK时间离散化,其中在RK方法的每个阶段引入不同的源项近似,以确保总能量守恒。一个精心设计的球对称的斜率限制器也被引入,以消除附近的不连续性的振荡,同时保持良好的平衡和总能量守恒的属性。广泛的数值例子-包括玩具模型的恒星核心崩溃的现象学状态方程,导致核心反弹和冲击形成-提供演示所需的性能的方法,包括良好的平衡性能,高阶精度,冲击捕获能力,和总能量守恒。

英文摘要:

This paper presents high-order Runge-Kutta (RK) discontinuous Galerkin methods for the Euler-Poisson equations in spherical symmetry. The scheme can preserve a general polytropic equilibrium state and achieve total energy conservation up to machine precision with carefully designed spatial and temporal discretizations. To achieve the well-balanced property, the numerical solutions are decomposed into equilibrium and fluctuation components which are treated differently in the source term approximation. One non-trivial challenge encountered in the procedure is the complexity of the equilibrium state, which is governed by the Lane-Emden equation. For total energy conservation, we present second- and third-order RK time discretization, where different source term approximations are introduced in each stage of the RK method to ensure the conservation of total energy. A carefully designed slope limiter for spherical symmetry is also introduced to eliminate oscillations near discontinuities while maintaining the well-balanced and total-energy-conserving properties. Extensive numerical examples -- including a toy model of stellar core-collapse with a phenomenological equation of state that results in core-bounce and shock formation -- are provided to demonstrate the desired properties of the proposed methods, including the well-balanced property, high-order accuracy, shock capturing capability, and total energy conservation.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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