论文标题

最佳Chebyshev Smoother和单方面的V-Cycles

Optimal Chebyshev Smoothers and One-sided V-cycles

论文作者

Phillips, Malachi, Fischer, Paul

论文摘要

由不可压缩的Navier-Stokes方程的光谱元件离散化产生的泊松方程的解决方案需要强大的预处理策略。一种这样的策略就是多人。为了实现多方方法的潜力,需要有效的平滑策略。 Chebyshev多项式平滑被证明是一种有效的更顺畅。但是,有几种改进需要做出的改进,尤其是以对称性为代价。对于每次迭代的相同成本,具有$ K $订单Chebyshev多项式平滑的完整V周期可以用半V周期替换,订单为$ 2K $ CHEBYSHEV多项式平滑,其中省略了V-Cycle上的省略。在Multigrid近似属性常数$ C $大的情况下,选择省略后熟人而有利于更高级的Chebyshev前表面的选择是有利的。显示了Lottes的第四个Chebyshev多项式更平滑的结果。这些方法表明,对标准的Chebyshev多项式更加顺畅。作者在$ p $ - 几何的多机以及有限差异的2D模型问题中证明了该方案的有效性。

The solution to the Poisson equation arising from the spectral element discretization of the incompressible Navier-Stokes equation requires robust preconditioning strategies. One such strategy is multigrid. To realize the potential of multigrid methods, effective smoothing strategies are needed. Chebyshev polynomial smoothing proves to be an effective smoother. However, there are several improvements to be made, especially at the cost of symmetry. For the same cost per iteration, a full V-cycle with $k$ order Chebyshev polynomial smoothing may be substituted with a half V-cycle with order $2k$ Chebyshev polynomial smoothing, wherein the smoother is omitted on the up-leg of the V-cycle. The choice of omitting the post-smoother in favor of higher order Chebyshev pre-smoothing is shown to be advantageous in cases where the multigrid approximation property constant, $C$, is large. Results utilizing Lottes's fourth-kind Chebyshev polynomial smoother are shown. These methods demonstrate substantial improvement over the standard Chebyshev polynomial smoother. The authors demonstrate the effectiveness of this scheme in $p$-geometric multigrid, as well as a 2D model problem with finite differences.

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