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arXiv 2408.00396math.NAcs.NA
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具有大(甚至无限)微调参数的连续数据同化分析

Analysis of continuous data assimilation with large (or even infinite) nudging parameters

Amanda Diegel, Xuejian Li, Leo G. Rebholz

AI总结:

本文针对偏微分方程离散化中的连续数据同化,提出基于加权内积的误差分解方法,证明热方程和Navier-Stokes方程在任意大微调参数下仍可获得与参数无关的最优长时间精确解。

摘要:

本文考虑偏微分方程(PDE)离散化中的连续数据同化(CDA),其中微调参数可以取任意大。我们证明,对于热方程和Navier-Stokes方程(使用隐式时间步进方法),此类参数可以获得长时间最优精确解,并且误差界不会随着微调参数变大而增长。现有的理论结果要么证明了最优精度但误差随微调参数缩放,要么证明了与微调参数无关的次优精度。改进分析的关键思想是基于加权内积对误差进行分解,该内积包含(通过构造对称的)微调项,并证明来自该加权内积的投影误差是最优的且与微调参数无关。我们将该思想应用于热方程和Navier-Stokes方程的BDF2 - 有限元离散化,以表明使用CDA时,对于足够大的微调参数,它们将允许与微调参数无关的最优长时间精确解。针对热方程、流体输运方程、Navier-Stokes和Cahn-Hilliard给出了若干数值测试,以说明该理论。

英文摘要:

This paper considers continuous data assimilation (CDA) in partial differential equation (PDE) discretizations where nudging parameters can be taken arbitrarily large. We prove that long-time optimally accurate solutions are obtained for such parameters for the heat and Navier-Stokes equations (using implicit time stepping methods), with error bounds that do not grow as the nudging parameter gets large. Existing theoretical results either prove optimal accuracy but with the error scaled by the nudging parameter, or suboptimal accuracy that is independent of it. The key idea to the improved analysis is to decompose the error based on a weighted inner product that incorporates the (symmetric by construction) nudging term, and prove that the projection error from this weighted inner product is optimal and independent of the nudging parameter. We apply the idea to BDF2 - finite element discretizations of the heat equation and Navier-Stokes equations to show that with CDA, they will admit optimal long-time accurate solutions independent of the nudging parameter, for nudging parameters large enough. Several numerical tests are given for the heat equation, fluid transport equation, Navier-Stokes, and Cahn-Hilliard that illustrate the theory.

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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