论文标题

在各向异性网格上的Stokes方程的不合格压力量有限元法

A nonconforming pressure-robust finite element method for the Stokes equations on anisotropic meshes

论文作者

Apel, Thomas, Kempf, Volker, Linke, Alexander, Merdon, Christian

论文摘要

(Navier-)Stokes方程的大多数经典有限元元素方案既不是压力的,也不是在一般各向异性三角剖分上稳定的。每当Stokes Momentum平衡以强大而复杂的压力梯度主导时,缺乏压力的速度误差可能会导致较大的速度误差。这是一种方法的结果,该方法无法完全满足差异约束。但是,仅通过使用$ \ MathBf {h}(\ permatorName {div})$构造速度重建算子的$ \ MathBf {h}(\ peripatorName {div})$,通常可以通过对外部强迫术语进行了改进的离散术语的稳定方案通常可以做出压力。到目前为止,这种方法仅在形状定型三角剖分上进行了分析。目前的贡献的新颖性是,在任意网格上具有稳定的Fortin运算符的Crouzeix-raviart方法的重建方法与对各向异性元素的互插错误的结果相结合,用于raviart-thomas-thomas-thomas和Brezzi-douglas-douglas-douglas-douglas-douglas-douglas-douglas-douglas-douglas-douglas-douglas-douglas-douglas-douglas-douglas-douglas-douglas-douglas-douglas-douglas-douglas-douglas-douglas-marini类型,将其分类为大量分类。数值示例在2D和3D测试案例中证实了理论结果。

Most classical finite element schemes for the (Navier-)Stokes equations are neither pressure-robust, nor are they inf-sup stable on general anisotropic triangulations. A lack of pressure-robustness may lead to large velocity errors, whenever the Stokes momentum balance is dominated by a strong and complicated pressure gradient. It is a consequence of a method, which does not exactly satisfy the divergence constraint. However, inf-sup stable schemes can often be made pressure-robust just by a recent, modified discretization of the exterior forcing term, using $\mathbf{H}(\operatorname{div})$-conforming velocity reconstruction operators. This approach has so far only been analyzed on shape-regular triangulations. The novelty of the present contribution is that the reconstruction approach for the Crouzeix-Raviart method, which has a stable Fortin operator on arbitrary meshes, is combined with results on the interpolation error on anisotropic elements for reconstruction operators of Raviart-Thomas and Brezzi-Douglas-Marini type, generalizing the method to a large class of anisotropic triangulations. Numerical examples confirm the theoretical results in a 2D and a 3D test case.

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