论文标题

二维Helmholtz谐振阵列。第二部分。匹配的渐近扩展,用于特殊尺度的谐振器

Two-dimensional Helmholtz resonator arrays. Part II. Matched asymptotic expansions for specially-scaled resonators

论文作者

Smith, M. J. A., Abrahams, I. D.

论文摘要

我们提出了一种解决方案方法,该方法将匹配的渐近学的方法与多极扩展的方法结合在一起,以确定圆柱helmholtz谐振器阵列阵列的带结构。与光圈宽度相比(特殊尺度的极限)相比,随着壁厚的厚度非常大,谐振器的几何形状被考虑到极限。在此制度中,发现I部分的现有治疗方法,具有更新的参数,可以返回伪造的光谱行为。我们得出一个正规化系统,该系统克服了此问题,并在此环境中针对低频分散方程得出了紧凑的渐近描述。在特殊尺度的极限中,我们的渐近分散方程不仅恢复了第一条带表面,而且还延伸到高频率,但仍然是次波长的频率。概述了均质处理,用于描述所有壁厚厚度的谐振器阵列的有效大量模量和有效的密度张量。我们证明,特殊尺寸的谐振器能够达到异常较低的Helmholtz谐振频率,并呈现闭合表达式,以明确确定这些频率。我们预计,此处概述的分析表达式和配方可能在工业和其他应用中很有用。

We present a solution method which combines the method of matched asymptotics with the method of multipole expansions to determine the band structure of cylindrical Helmholtz resonators arrays in two dimensions. The resonator geometry is considered in the limit as the wall thickness becomes very large compared with the aperture width (the specially-scaled limit). In this regime, the existing treatment in Part I, with updated parameters, is found to return spurious spectral behaviour. We derive a regularised system which overcomes this issue and also derive compact asymptotic descriptions for the low-frequency dispersion equation in this setting. In the specially-scaled limit, our asymptotic dispersion equation not only recovers the first band surface but also extends to high, but still subwavelength, frequencies. A homogenisation treatment is outlined for describing the effective bulk modulus and effective density tensor of the resonator array for all wall thicknesses. We demonstrate that specially-scaled resonators are able to achieve exceptionally low Helmholtz resonant frequencies, and present closed-form expressions for determining these explicitly. We anticipate that the analytical expressions and the formulation outlined here may prove useful in industrial and other applications.

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