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arXiv 1709.08477math.NAcs.NA
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基于能量的Fourier-Galerkin法与有限元法的比较

Energy-based comparison between the Fourier--Galerkin method and the finite element method

Jaroslav Vondřejc, Tom W. J. de Geus

摘要:

傅里叶-伽辽金方法(简称FFTH)在数值均匀化中得到了广泛的应用,因为它可以处理具有大量自由度的问题。由于该方法在线性求解器中结合了快速傅里叶变换(FFT),因此与传统的有限元法(FEM)相比,它被认为在计算和存储需求方面提供了改进。在这里,我们系统地比较了这两种方法使用的能量范数的局部域,这有明确的物理解释是错误的均匀化属性。这使得在相同的近似精度水平的内存和计算需求的比较。我们表明,该方法的有效性依赖于光滑性(规律性)的解决方案,从而对材料系数。由于其近似特性,有限元优于FFTH的问题,跳跃的材料系数,而矛盾的结果观察的情况下,材料系数在空间连续变化。FFTH得益于线性系的良好调节,与自由度的数量无关,但通常需要更多的自由度来达到相同的近似精度。对于其他基于FFT的格式、非线性问题和对偶问题(需要在FEM中进行特殊处理,但在FFTH中不需要),需要进行更多的研究。

英文摘要:

The Fourier-Galerkin method (in short FFTH) has gained popularity in numerical homogenisation because it can treat problems with a huge number of degrees of freedom. Because the method incorporates the fast Fourier transform (FFT) in the linear solver, it is believed to provide an improvement in computational and memory requirements compared to the conventional finite element method (FEM). Here, we systematically compare these two methods using the energetic norm of local fields, which has the clear physical interpretation as being the error in the homogenised properties. This enables the comparison of memory and computational requirements at the same level of approximation accuracy. We show that the methods' effectiveness relies on the smoothness (regularity) of the solution and thus on the material coefficients. Thanks to its approximation properties, FEM outperforms FFTH for problems with jumps in material coefficients, while ambivalent results are observed for the case that the material coefficients vary continuously in space. FFTH profits from a good conditioning of the linear system, independent of the number of degrees of freedom, but generally needs more degrees of freedom to reach the same approximation accuracy. More studies are needed for other FFT-based schemes, non-linear problems, and dual problems (which require special treatment in FEM but not in FFTH).

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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