| 非均匀波导中的声聚焦 |
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| 引用本文： | 郭威,杨德森.非均匀波导中的声聚焦[J].物理学报,2020(7):90-101. |
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| 作者姓名： | 郭威 杨德森 |
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| 作者单位： | 哈尔滨工程大学;海洋信息获取与安全工业和信息化部重点实验室（哈尔滨工程大学）;哈尔滨工程大学 |
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| 摘 要： | 理论研究了声波在非均匀波导中的空间聚焦问题,利用多模态导纳法构建波导内任意位置处声压与入射声压在模态域的映射关系,计算使声波聚焦于空间某位置时的最佳入射波,并画出了相应的聚焦声场.研究了三种非均匀情况:水平变截面波导、含散射体波导以及声速垂直变化波导.结果表明,当输入最佳入射波时,在非均匀波导中可以产生良好的单点或多点声聚焦效果,声波的聚焦过程充分地利用了波导结构及介质非均匀性对声波的散射作用.
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| 关 键 词： | 声聚焦 非均匀波导 多模态导纳法 |
Sound focusing in inhomogeneous waveguides |
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| Guo Wei,Yang De-Sen.Sound focusing in inhomogeneous waveguides[J].Acta Physica Sinica,2020(7):90-101. |
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| Authors: | Guo Wei Yang De-Sen |
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| Affiliation: | (Acoustic Science and Technology Laboratory,Harbin Engineering University,Harbin 150001,China;Key Laboratory of Marine Information Acquisition and Security(Harbin Enhineering University),Ministry of Industry and Information,Harbin 150001,China;College of Underwater Acoustic Engineering,Harbin Engineering University,Harbin 150001,China) |
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| Abstract: | A method for analytically studying sound focusing in inhomogeneous waveguides is presented.From the viewpoint of acquiring the maximum acoustic pressure at an arbitrary position with normalized energy flux injection,optimal incident waves can be derived based on the multimodal admittance method.The method involves two steps.The first step is to expand the wave solution onto a complete orthogonal basis set so that the Helmholtz equation can be transformed into two sets of first-order coupled differential equations in the modal domain.The second step is to solve the coupled equations numerically by introducing admittance matrices and propagators,which can be used to derive reflection matrices and transmission matrices.Using the multimodal admittance method,one can circumvent the contamination caused by exponentially diverging evanescent modes and acquire stable wave solutions.Then the mapping between the acoustic pressure at an arbitrary position and that of the incident wave can be constructed,and this mapping changes the problem of wave focusing into solving the extrema of inner products in Hilbert space.The optimal incident waves that generate wave focusing at an arbitrary position can be readily computed together with the corresponding wave solutions.In this paper,we study the sound focusing in waveguides with varying cross-sections,scatterers and sound-speed profiles.The results show that the optimal incident waves will take full advantage of wave scattering caused by the boundaries and inhomogeneities during propagation to achieve the maximum pressure at foci,leading to good single-point and multi-point sound focusing performance.In addition,we find when injecting the spatially sampled optimal incident waves or the optimal incident waves with random perturbations,the resultant wave focusing phenomena will be still apparent.The focusing behaviors are highly robust to the perturbations of the moduli of the incident waves and slightly less robust to that of the arguments of the incident waves.Our method is also available for analyzing wave focusing in other kinds of inhomogeneous waveguides.We believe that our research can provide guidance on designing acoustic lenses or metamaterials to focus sound waves in complex media,and can offer inspiration in wave communications,imagings and nondestructive testing. |
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| Keywords: | sound focusing inhomogeneous waveguides multimodal admittance method |
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