Calculation And Characteristic Analysis Of Medium And Low Frequency Ocean Sound Field In Typical Submarine Environment Based On Finite Element Method

As the lower boundary of sound propagation in the ocean,the seabed sediment is of great significance to the study of the acoustic field in the ocean.The acoustic characteristics of the seabed not only directly affect the prediction accuracy of the ocean acoustic field,but also affect the performance of sonar equipment and the detection of buried objects on the seabed.Scholars at home and abroad have increasing requirements for modeling,simulation and numerical prediction of the acoustic field environment in the seabed,and the construction of the acoustic propagation model in the seabed environment must conform to the parameters and topographical characteristics of the seabed in the actual environment.Based on the research results of predecessors,this paper carried out a series of basic simulation research work based on the actual seabed data information in a sea area of the South China Sea,combined with the frequency band range(100Hz to 10 k Hz)of the current seabed detection equipment.Using the finite element method to simulate the middle and low frequency sound fields under different sea bottom materials,different sea topographic environments,and different sound sources,the acoustic characteristics were studied and analyzed,and the basic characteristics and changing laws of the acoustic characteristics were clarified.This paper firstly verifies the accuracy of using the finite element method to simulate and calculate the propagation of medium and low frequency submarine sound.Considering the influence of parameters such as different seabed sediment conditions,sediment layers,and topographical environmental conditions,combined with actual sediment data and actual terrain data in a sea area of the South China Sea,based on the underwater sound propagation theory and the ground sound propagation theory model,construct different ocean sound field models in typical seabed environments,and use the COMSOL finite element software to establish a finite element simulation model of the sound field in a typical seabed environment,to realize the simulation of the middle and low frequency sound field under different seabed environmental conditions,acoustic characteristic parameters such as sound field sound pressure value,propagation loss,sound energy flow and sound signal waveform are extracted and researched and analyzed.In addition,this paper compares and analyzes the difference between the sound field simulation of the two-dimensional axisymmetric model and the three-dimensional model,and simulates and analyzes the sound propagation characteristics in the three-dimensional seamount environment model.Based on the above research,this paper further studies the influence of different seabed environmental conditions on the performance of sonar equipment,the change of the ocean sound field when there are seabed buried objects,and explores the changing rules of related characteristics.According to the simulation results of this paper,the conclusions drawn from the research on the characteristics of the ocean acoustic field in a typical seabed environment and related applications can be summarized in three aspects:(1)The influence of seabed bottom:In the fluid medium seabed,most of the sound wave energy leaks from the seawater into the seabed,and the sound wave energy in seawater decays very quickly;When the seabed medium type is elastic medium or poroelastic medium,a large amount of acoustic wave energy is retained in seawater,surface waves are more likely to be excited at the seabed interface,and acoustic energy decays faster in the seabed;(2)Influence of seabed terrain conditions: the more complex the seabed topography environment is,the more obvious the acoustic phenomena such as the acoustic convergence area,sound shadow area,and reverberation caused by the seabed environment will be.The greater the loss of sound wave energy,the greater its impact on sound propagation in the seabed environment;the higher the height of the seamount or the more severe the fluctuation of the seabed topography in the seabed environment,the more obvious its effect on the convergence and blocking of sound energy;(3)Application analysis: at the same operating frequency,the closer the seabed bottom is to a fluid medium,the more complex the seabed topography is,and the smaller the active sonar range is;The existence of buried objects makes the sound propagation loss in water and the particle displacement propagation loss at the seabed interface increase and change abruptly at the location of the buried object;the more complex the topography of the seabed is,the less impact the existence of buried objects has on the ocean acoustic field.The research work in this paper can make up for the deficiencies in the current study of submarine acoustics,and provide a certain theoretical support for the sonar detection performance in typical submarine environments and the development of submarine buried object detection technology.