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arXiv 2103.02112math.NAcs.NA
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不连续Galerkin离散的多层方法应该使用不连续插值算子吗?

Should multilevel methods for discontinuous Galerkin discretizations use discontinuous interpolation operators?

Jose Pablo Lucero Lorca, Martin Jakob Gander

摘要:

不连续Galerkin(DG)离散的多层预条件子被广泛用于求解椭圆型方程,而插值算子是这种求解器的一个主要组成部分,它将信息从粗网格传递到细网格。经典的插值算子给出连续的插值,但由于DG解是自然不连续的,人们可能会怀疑是否不应该使用不连续插值算子进行DG离散化。我们考虑一个不连续的插值算子的参数,控制的不连续性,并确定最佳的选择不连续性,导致最快的求解器为特定的一维对称内部惩罚DG离散化模型问题。此外,我们表明,我们的优化提供了一个完美的聚类光谱具有高的几何重数,这是非常有利的Krylov求解器使用的方法作为其预条件。最后,我们展示了最优选择对更高维度的适用性。

英文摘要:

Multi-level preconditioners for Discontinuous Galerkin (DG) discretizations are widely used to solve elliptic equations, and a main ingredient of such solvers is the interpolation operator to transfer information from the coarse to the fine grid. Classical interpolation operators give continuous interpolated values, but since DG solutions are naturally discontinuous, one might wonder if one should not use discontinuous interpolation operators for DG discretizations. We consider a discontinuous interpolation operator with a parameter that controls the discontinuity, and determine the optimal choice for the discontinuity, leading to the fastest solver for a specific 1D symmetric interior penalty DG discretization model problem. We show in addition that our optimization delivers a perfectly clustered spectrum with a high geometric multiplicity, which is very advantageous for a Krylov solver using the method as its preconditioner. Finally, we show the applicability of the optimal choice to higher dimensions.

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