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arXiv 1912.11596math.NAcs.NA
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超粘性显式龙格-库塔法的强稳定性

Enforcing strong stability of explicit Runge--Kutta methods with superviscosity

Zheng Sun, Chi-Wang Shu

摘要:

一个时间离散方法称为强稳定的,如果它的数值解的范数是非增的。众所周知,即使对于线性半负问题,许多显式Runge-Kutta(RK)方法也不能保持这一性质。在本文中,我们加强强稳定性通过修改的方法与超粘性,这是一种常用的谱方法的数值技术。我们提出了两种方法,修改的方法和滤波方法的稳定。修正方法是通过在半负算子中加入高阶超粘性项来实现的;滤波方法是通过求解具有小超粘性的扩散或色散问题来对解进行后处理。对于线性问题,大多数显式RK方法可以用任何一种方法稳定而不会出现精度退化。此外,我们证明了一个尖锐的边界(直到一个等号)的扩散超粘性,以确保强稳定性。我们导出的一般色散扩散超粘的边界也被数值验证是尖锐的。对于非线性问题,研究了一种滤波镇定方法。数值例子与线性非正规常微分方程系统和间断Galerkin近似的守恒律进行验证我们的分析和测试的性能。

英文摘要:

A time discretization method is called strongly stable, if the norm of its numerical solution is nonincreasing. It is known that, even for linear semi-negative problems, many explicit Runge--Kutta (RK) methods fail to preserve this property. In this paper, we enforce strong stability by modifying the method with superviscosity, which is a numerical technique commonly used in spectral methods. We propose two approaches, the modified method and the filtering method for stabilization. The modified method is achieved by modifying the semi-negative operator with a high order superviscosity term; the filtering method is to post-process the solution by solving a diffusive or dispersive problem with small superviscosity. For linear problems, most explicit RK methods can be stabilized with either approach without accuracy degeneration. Furthermore, we prove a sharp bound (up to an equal sign) on diffusive superviscosity for ensuring strong stability. The bound we derived for general dispersive-diffusive superviscosity is also verified to be sharp numerically. For nonlinear problems, a filtering method is investigated for stabilization. Numerical examples with linear non-normal ordinary differential equation systems and for discontinuous Galerkin approximation of conservation laws are performed to validate our analysis and to test the performance.

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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