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arXiv 2509.03471math.NAcs.NA
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时间分数阶相场模型中具有渐近相容能量律的线性松弛格式

Linear Relaxation Schemes with Asymptotically Compatible Energy Law for Time-Fractional Phase-Field Models

Hui Yu, Zhaoyang Wang, Ping Lin

AI总结:

针对时间分数阶相场方程,提出结合$L1^{+}$-CN离散与辅助变量的变步长线性松弛格式,具备时间二阶精度、能量稳定性及渐近相容的离散能量耗散律,数值实验验证了其有效性与变量一致性。

摘要:

本文针对具有一般多项式形式自由能密度的时间分数阶相场方程,提出了一种变时间步长线性松弛格式。我们采用$L1^{+}$-CN公式离散分数阶导数,并引入辅助变量来近似非线性项,通过直接求解代数方程实现,而非像不变能量二次化(IEQ)方法和标量辅助变量(SAV)方法那样求解微分代数方程。所提出的半离散格式在时间上具有二阶精度,且辅助变量与原始变量之间的不一致性不会随时间恶化。此外,我们以时间分数阶体积守恒Allen-Cahn方程、时间分数阶Cahn-Hilliard方程以及时间分数阶Swift-Hohenberg方程为例,证明了所构造的格式是能量稳定的,并且当分数阶参数$\alpha\rightarrow 1^{-}$时,离散能量耗散律与经典能量耗散律渐近相容。若干数值算例验证了所提格式的有效性。特别地,数值结果证实辅助变量与原始变量始终保持良好的一致性,在系统达到稳态之前,两者之间的误差不会持续增大。

英文摘要:

In this paper, we propose a variable time-step linear relaxation scheme for time-fractional phase-field equations with a free energy density in general polynomial form. The $L1^{+}$-CN formula is used to discretize the fractional derivative, and an auxiliary variable is introduced to approximate the nonlinear term by directly solving algebraic equations rather than differential-algebraic equations as in the invariant energy quadratization (IEQ) and the scalar auxiliary variable (SAV) approaches. The developed semi-discrete scheme is second-order accurate in time, and the inconsistency between the auxiliary and the original variables does not deteriorate over time. Furthermore, we take the time-fractional volume-conserved Allen-Cahn equation, the time-fractional Cahn-Hilliard equation, and the time-fractional Swift-Hohenberg equation as examples to demonstrate that the constructed schemes are energy stable and that the discrete energy dissipation law is asymptotically compatible with the classical one when the fractional-order parameter $α\rightarrow 1^{-}$. Several numerical examples demonstrate the effectiveness of the proposed scheme. In particular, numerical results confirm that the auxiliary variable remains well aligned with the original variable, and the error between them does not continue to increase over time before the system reaches steady state.

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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