耦合微扰简正波方法与孤立子内波
Coupled perturbed mode method and solitary internal wave
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摘要: 水平变化环境下声场简正波解的计算精度和效率取决于本地简正波的计算方法。提出一种完备的一阶微扰理论方法,并引入迭代算法,获得了本地简正波水平波数和本征函数的精确表达式。数值结果表明,改进后的微扰简正波方法得到的简正波水平波数和本征函数精度比前人方法更高,与KRAKENC计算结果吻合较好,而计算速度比KRAKENC快100倍。同时将微扰简正波方法与耦合简正波理论结合,应用到海水声速水平变化剧烈的孤立子内波群环境。数值结果表明,该方法计算得到的传播损失与COUPLE07在单次散射近似下的计算结果吻合较好,计算速度比COUPLE07快25倍,并将该方法在声场计算中的适用频率提高到了3 kHz。Abstract: In shallow water environment, sound propagation through internal solitary waves involves mode coupling. The local normal modes in range-dependent environment can be found using a perturbation method developed by Higham and Tindle, which yields accurate and fast normal mode solutions when combined with coupled-mode theory. The method of Higham and Tindle is limited to low frequency (≤ 400 Hz). In order to increase the work frequency of the perturbation method in solitary internal wave environment, we keeping the high-order terms in the perturbation method and using the iteration algorithm, so we get the more accurate local normal modes, and also increase the work frequency of this computation method for sound waves to 3 kHz. The approach has been verified in internal solitary wave packet environment