海水弛豫效应对有限振幅声波传播的影响

摘要

To study the influence of the seawater relaxation effect on the finite amplitude sound propagation, the propagation model and the acoustic Reynolds number in relaxation medium are obtained by adding the modified terms of the relaxation processes to Burgers equation. When the frequency of the acoustic wave is far less than the relaxation frequency of the medium,a numerical simulation is conducted for the finite amplitude sound propagation, and the relaxation effect caused by magnesium sulfate on the sound propagation is analyzed. Results show that the formation of shock wave in seawater has certain threshold. The shock wave is formed when the acoustic Reynolds number exceeds the threshold, and excessive absorption caused by the relaxation effect delays formation of the shock wave. In addition,the amplitude of the shock wave attenuates as the distance increases,and the shock wave will not be formed when the acoustic Reynolds number below the threshold.%为了研究海水弛豫效应对有限振幅声波传播的影响,本文将海水弛豫过程的修正项加入到有限振幅声波的传播模型中,得到了弛豫介质中有限振幅声波的传播模型及声雷诺数.当声波频率远小于介质的弛豫频率时,结合数值算法,对声波的传播进行数值模拟,分析了硫酸镁弛豫效应对声波传播的影响.研究表明:海水介质中冲击波的形成具有一定的阈值条件,当声雷诺数超过阈值条件时会形成冲击波,此时弛豫效应引起的逾量吸收具有推迟冲击波形成的作用,且冲击波的幅度随着传播距离的增大而衰减,而当声雷诺数没有达到阈值条件时不会形成冲击波.