Effect of Schooling on Flow-Generated Noise in Fish: The Role of Fin Flapping Phase and Spatial Arrangement*

High-fidelity simulations are utilized to investigate how schooling affects the noise generated by fish swimming with their caudal fins. The simulations capture both the flow and the far-field hydrodynamic sound produced by the fluctuating pressure on these carangiform swimmers. We explore the influence of the number of swimmers, the phase relationships of their fin movements, and their spatial configuration. Results indicate that the phase synchronization of fin movements is a crucial factor in the total sound emitted by a group of swimmers. In smaller schools, choosing an optimal phase relationship among the swimmers can greatly reduce the total sound radiated to the far-field. Additionally, the spatial arrangement of the swimmers impacts the overall noise production. In larger schools, even with highly uncoordinated fin movements, there is a significant reduction in far-field sound intensity. These findings have important implications for understanding fish behavior and the development of bioinspired aquatic vehicles.