Accelerated Acoustic Boundary Element Method and the Noise Generation of an Idealized School of Fish
Accelerated Acoustic Boundary Element Method and the Noise Generation of an Idealized School of Fish
复制标题
加速声学边界元法和理想鱼群的噪声产生
DOI：
10.1007/978-3-319-76780-2_11
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发表时间：
2017
期刊：
影响因子：
--
通讯作者：
J. Jaworski
中科院分区：
文献类型：
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作者：
Nathan Wagenhoffer;K. Moored;J. Jaworski
瞬态，二维声学边界元求解器开发使用双层势加速的快速多重法应用于多体，外部场问题。该配方进行了验证数值对规范的辐射和散射配置的单个和多个机构，并特别注意评估模型误差。声学框架应用于模拟鱼群遇到2S和2 P类涡街时的涡声产生。涡街道的固定身份直线移动过去的二维鱼，这是由四个固定的NACA 0012翼型排列在一个菱形图案的代表性学校在静止的流体。鱼状物体上的诱导速度决定了声学方法计算声学远场中观察到的声音的时变输入边界条件。由此产生的涡流噪声作为Strouhal数的函数进行检查，其中发现最大声强度为\（St \approximat0.2\），并且在\（0.3< St < 0.4\）范围内观察到游泳者的声强度平台。在没有背景平均流影响的情况下，数值结果进一步表明，Strouhal数的取值可以改变涡尾流中理想鱼群的声学指向性，使其向上游或下游方向辐射噪声，这对捕食者-猎物声场相互作用的研究和安静仿生水下装置的设计具有重要意义.
A transient, two-dimensional acoustic boundary element solver is developed using double-layer potentials accelerated by the fast multiple method for application to multibody, external field problems. The formulation is validated numerically against canonical radiation and scattering configurations of single and multiple bodies, and special attention is given to assessing model error. The acoustic framework is applied to model the vortex sound generation of schooling fish encountering 2S and 2P classes of vortex streets. Vortex streets of fixed identity are moved rectilinearly in a quiescent fluid past representative schools of two-dimensional fish, which are composed of four stationary NACA0012 airfoils arranged in a diamond pattern. The induced velocity on the fish-like bodies determines the time-dependent input boundary condition for the acoustic method to compute the sound observed in the acoustic far field. The resulting vortex noise is examined as a function of Strouhal number, where a maximum acoustic intensity is found for \(St \approx 0.2\), and an acoustic intensity plateau is observed for swimmers in the range of \(0.3< St < 0.4\). In the absence of background mean flow effects, numerical results further suggest that the value of Strouhal number can shift the acoustic directivity of an idealized school in a vortex wake to radiate noise in either upstream or downstream directions, which may have implications for the the study of predator-prey acoustic field interactions and the design of quiet bio-inspired underwater devices.