Research On Ocean Sound Propagation Characteristics Based On Finite Element Method

Ocean sound field simulation is one of the ways to study the law of acoustic signal propagation characteristics in the ocean.In recent years,with the increasing requirements of the researchers for the ocean sound field modeling environment,the constructed ocean sound field model is more and more simulated to the actual marine environments' parameters and topographical features.However,the traditional ocean sound field calculation model which calculate the acoustic propagation result by considered some theoretical approximations and assumptions in the wave equation.That they are often impossible to accurately solve the sound propagation law in accordance with the characteristics of the actual marine environment.In this paper,we use the FEM(finite element model)based on the Comsol Multiphysics platform to simulate and analyze the low-frequency acoustic propagation characteristic in the shallow water.Considered the influence of seafloor shear wave and certain seabed inclination on the sound propagation law in the actual marine environment and try to construct the three-dimensional ocean sound field model to analyze influence of acoustic propagation low with the model which is exist solitary internal waves.The main findings of the study are as follows:(1)For using the finite element method to simulate the acoustic propagation characteristics of two-dimensional and two-dimensional axisymmetric models and comparing the simulation results calculated by the traditional sound field method RAM and COUPLE.We can find that FEM can calculate the result more accuracy,and completely consistent with the Global Coupled Normal Wave Model(DGMCM)which is a performs very well on current accuracy model.It is proved that the FEM can be used to calculate a more accurate solution than the traditional sound field calculation method.(2)For the propagation law of acoustic signals in the up-sloping and down-sloping elastic seabed environment under the influence of shear waves,it can be found that the changes of sound source frequency,seabed topography and seafloor acoustic parameters have obviously influenced the acoustic signal propagation characteristics in the water layer.At the same time,when the acoustic signal propagates in the up-sloping elastic bottom environment,we can find that some sound energy will leak from the water layer to the elastic bottom,the amount of acoustic energy lacked into the bottom is proportional to the sound source frequency and the depth of water layer where the sound source is located.When the acoustic signal propagates in the down-sloping elastic bottom environment,it can be found that acoustic energy propagate in the down-sloping elastic bottom will propagate in the form of interface waves at the seawater-seabed boundary.(3)When the acoustic signal propagates in a three-dimensional sound field with the internal solitary wave velocity distribution characteristics.It can be clearly observed that with the movement of internal solitary wave in the model,the effect of acoustic signal deflection on the vertical component remains unchanged.Due to the three-dimensional effort of the internal solitary on the acoustic signal propagation,we can find that following the increase of angle between the direction of sound propagation and the internal solitary wave front.For the more,the energy possessed by acoustic signal is become weakening and the angle of acoustic signal deflection caused by the internal solitary wave is increasing.These studies have been used to explore how to simulate the acoustic signal propagation characteristic in the actual complex parameters and terrain.And provides some reference conclusions of the influence of acoustic signals propagation characteristic in the elastic bottom model or three-dimensional model with actual acoustic parameters.