da Silva Andrey Ricardo, Duarte Victor Mosimann
Laboratory of Vibration and Acoustics, Department of Mechanical Engineering, Federal University of Santa Catarina, Campus Universitário Trindade, Florianópolis, Santa Catarina 88040-900, Brazil.
J Acoust Soc Am. 2024 Oct 1;156(4):2211-2219. doi: 10.1121/10.0030405.
Although the concept of acoustic Luneburg lenses was first proposed more than 50 years ago, its physical realization became feasible only in the last decade, owing to advancements in metamaterials research. Since then, numerous studies have explored the potential of these devices from the acoustic perspective. However, a comprehensive understanding of the mechanisms associated with the optimal performance of these lenses remains underexplored in the literature. This study conducts numerical investigations to identify parameters enhancing acoustic gain in Luneburg lenses. The analyses are conducted with the results obtained from a flattened Luneburg lens model based on the lattice Boltzmann method. Results, scaled with the Helmholtz number, He, indicate that the maximum acoustic gain occurs at He = 1.3, with performance sustained over a wide range of Helmholtz values. Analysis of surface impedance reveals underperformance for Helmholtz values below 0.5 due to viscous dissipation and above 2.0 due to Bragg reflections. These results provide a basis for evaluating the Helmholtz parameters that optimize the acoustic gain of Luneburg lenses.
尽管声学伦伯格透镜的概念早在50多年前就已首次提出，但由于超材料研究的进展，其物理实现直到最近十年才变得可行。从那时起，众多研究从声学角度探索了这些器件的潜力。然而，文献中对与这些透镜最佳性能相关的机制仍缺乏全面的了解。本研究进行了数值研究，以确定提高伦伯格透镜声学增益的参数。分析是基于格子玻尔兹曼方法从扁平伦伯格透镜模型获得的结果进行的。以亥姆霍兹数He进行缩放的结果表明，最大声学增益出现在He = 1.3时，并且在很宽的亥姆霍兹值范围内性能保持稳定。表面阻抗分析表明，由于粘性耗散，亥姆霍兹值低于0.5时性能不佳，而由于布拉格反射，亥姆霍兹值高于2.0时性能也不佳。这些结果为评估优化伦伯格透镜声学增益的亥姆霍兹参数提供了依据。
