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arXiv 2409.18328math.NAcs.NA
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准正交龙格-库塔投影方法

Quasi-Orthogonal Runge-Kutta Projection Methods

Mohammad R. Najafian, Brian C. Vermeire

AI总结:

本文提出一种用于显式龙格-库塔格式的准正交投影方法,通过将正交搜索方向投影到RK阶段导数张成的空间,在保持精度阶数、固定步长和最小额外成本的同时,有效守恒线性不变量并处理多种不变量系统。

摘要:

广泛的物理现象表现出辅助容许性准则,例如熵或各种能量的守恒,这些准则在偏微分方程精确解下隐式出现。然而,标准时间格式,如经典龙格-库塔(RK)方法,并不强制执行这些约束,导致精度和稳定性损失。投影是一种有效解决此缺陷的方法,通过在每个时间步结束时校正RK解。本文为显式RK格式引入了一种新颖的投影方法,称为准正交投影方法。该方法适用于包含单个(不一定凸的)不变泛函的系统、耗散系统以及包含多个不变量的系统。其工作原理是将正交搜索方向投影到由RK阶段导数张成的解空间中。通过这种方法,问题的线性不变量得以保留,时间步长保持固定,额外计算成本最小,且这些最优搜索方向保持了基础RK方法的精度阶数。这相比现有投影方法具有显著优势。数值结果表明,这些性质在多种应用中均在实践中得到验证。

英文摘要:

A wide range of physical phenomena exhibit auxiliary admissibility criteria, such as conservation of entropy or various energies, which arise implicitly under exact solution of their governing PDEs. However, standard temporal schemes, such as classical Runge-Kutta (RK) methods, do not enforce these constraints, leading to a loss of accuracy and stability. Projection is an efficient way to address this shortcoming by correcting the RK solution at the end of each time step. Here we introduce a novel projection method for explicit RK schemes, called a \textit{quasi-orthogonal} projection method. This method can be employed for systems containing a single (not necessarily convex) invariant functional, for dissipative systems, and for the systems containing multiple invariants. It works by projecting the orthogonal search direction(s) into the solution space spanned by the RK stage derivatives. With this approach linear invariants of the problem are preserved, the time step size remains fixed, additional computational cost is minimal, and these optimal search direction(s) preserve the order of accuracy of the base RK method. This presents significant advantages over existing projection methods. Numerical results demonstrate that these properties are observed in practice for a range of applications.

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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