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arXiv 2201.00920math.NAcs.NA
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时间分数阶Cahn-Hilliard模型变步长L1型格式的能量稳定性

Energy stability of variable-step L1-type schemes for time-fractional Cahn-Hilliard model

Bingquan Ji, Xiaohan Zhu, Hong-lin Liao

AI总结:

本文提出一种新技术估计分数阶Caputo导数L1型公式离散卷积核的最小特征值,为时间分数阶Cahn-Hilliard模型建立了变步长L1型格式的变分能量耗散定律,并证明其渐近相容性。

摘要:

离散时间分数阶导数的正定性是时间分数阶相场模型在能量意义上数值稳定性的基础。本文提出了一种新技术,用于估计由分数阶Caputo导数的非均匀L1、基于半网格的L1和时间平均L1公式生成的离散卷积核的最小特征值。主要的离散工具是离散正交卷积核和离散互补卷积核。随后,针对时间分数阶Cahn-Hilliard模型,建立了变步长L1型方法在离散层面上的某些变分能量耗散定律。结果表明,在分数阶极限$α\ ightarrow1$下,这些定律与经典Cahn-Hilliard方程的相关能量耗散定律是渐近相容的。文中还给出了数值算例及自适应时间步进程序,以证明所提方法的有效性。

英文摘要:

The positive definiteness of discrete time-fractional derivatives is fundamental to the numerical stability (in the energy sense) for time-fractional phase-field models. A novel technique is proposed to estimate the minimum eigenvalue of discrete convolution kernels generated by the nonuniform L1, half-grid based L1 and time-averaged L1 formulas of the fractional Caputo's derivative. The main discrete tools are the discrete orthogonal convolution kernels and discrete complementary convolution kernels. Certain variational energy dissipation laws at discrete levels of the variable-step L1-type methods are then established for time-fractional Cahn-Hilliard model.They are shown to be asymptotically compatible, in the fractional order limit $α\rightarrow1$, with the associated energy dissipation law for the classical Cahn-Hilliard equation. Numerical examples together with an adaptive time-stepping procedure are provided to demonstrate the effectiveness of the proposed methods.

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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