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arXiv 2006.02283math.NAcs.NA
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Cahn-Hilliard方程时空解的稳定FE方法

A Stable FE Method For the Space-Time Solution of the Cahn-Hilliard Equation

Eirik Valseth, Albert Romkes, Austin R. Kaul

摘要:

在其应用到矿物分离过程的建模中,我们提出了数值分析的Cahn-Hilliard方程采用时空离散的自动变分稳定有限元(AVS-FE)方法。AVS-FE方法是一种Petrov-Galerkin方法,它采用了Demkowicz和Gopalakrishnan的间断Petrov-Galerkin(DPG)方法的最佳间断检验函数的概念。然而,试验空间由全局连续的希尔伯特空间组成,例如H1和H(div)。因此,AVS-FE近似采用经典的C 0或Raviart-Thomas FE基函数。最佳检验函数保证了AVS-FE方法的数值稳定性,并导致对称和正定的离散系统。因此,AVS-FE方法可以在空间和时间上求解Cahn-Hilliard方程,而不需要限制CFL条件来决定时空单元的大小。我们提出了一个和两个在空间中的二维问题的数值验证。验证表明,在L2和H1规范的最佳收敛速度。网格自适应细化使用内置的误差估计的AVS-FE方法的结果。

英文摘要:

In its application to the modeling of a mineral separation process, we propose the numerical analysis of the Cahn-Hilliard equation by employing spacetime discretizations of the automatic variationally stable finite element (AVS-FE) method. The AVS-FE method is a Petrov-Galerkin method which employs the concept of optimal discontinuous test functions of the discontinuous Petrov-Galerkin (DPG) method by Demkowicz and Gopalakrishnan. The trial space, however, consists of globally continuous Hilbert spaces such as H1 and H(div). Hence, the AVS-FE approximations employ classical C0 or Raviart-Thomas FE basis functions. The optimal test functions guarantee the numerical stability of the AVS-FE method and lead to discrete systems that are symmetric and positive definite. Hence, the AVS-FE method can solve the Cahn-Hilliard equation in both space and time without a restrictive CFL condition to dictate the space-time element size. We present numerical verifications of both one and two dimensional problems in space. The verifications show optimal rates of convergence in L2 and H1 norms. Results for mesh adaptive refinements using a built-in error estimator of the AVS-FE method are also presented.

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