Wave-induced sound pressure from artificial fish reefs and applicability to sea environment improvement

对1996年实验中所采用的二维结构的流动进行了精确的数值模拟。对压力振动进行了计算，分析了压力振动的时间变化规律和振幅谱。在结构周围形成的涡及其行为与实验中观察到的非常相似。虽然在模拟中不能很好地再现压力中的高频振动，但在一定的频域内很好地模拟了振幅谱的增加。这在定性上与实验结果一致。利用立方型鱼礁模型在三维波池中进行了室内实验。实验研究了鱼礁数量及其排列方式对声压的影响。在实验研究的基础上，得到了以下结果：1)在原有鱼礁旁边增设鱼礁，增加了鱼礁间的速度，但没有增加声压。在鱼礁阵列的外围区域也得到了类似的结果。2)增设鱼礁外角前声压增大。这些结果表明，波浪与一组鱼礁以及水流与每个鱼礁之间的相互作用对局部声压特征起着重要作用。这表明在安装鱼礁时，有必要对布置进行详细调查。

Precise numerical calculation is performed to simulate a flow around two-dimensional structures which were emploved in the experiments carried out in 1996. The pressure vibration are also calculated and their time variations and amplitude spectra are analyzed. The vortices formed around the structure and their behaviors are confirmed to be very similar to those observed in the experiments. Although, the high frequency vibration in the pressure was not able to be reproduced well in the simulation, the amplitude spectrum was well simulated to be increased in a certain frequency domain. This agree with the experimental results in qualitative.Laboratory experiments are also conducted in the three dimensional wave basin using cubic type fish reef models. In the experiments effects of number of fish reef and their arrangements on the sound pressure are investigated. Based on the experimental study, following results are obtaind.1) The installing another fish reef beside the existing one enlarges the velocity between the reefs, however, it does not increase the sound pressure. Similar result is obtained in outer region of the array of the fish reefs.2) The sound pressure in front of the outer corner of the fish reef is enlarged by installing another one. These results suggest that the combined effect of interactions between wave and a group of fish reefs and between flow and each fish reef plays important roles on the characteristics of local sound pressure. This indicates the detail investigations on the arrangement are necessary in installing the fish reefs.