Study On Propagation Characteristics And Propagation Rules Of Ship Seismic Wave

This paper introduces the advantages and disadvantages of traditional sound field and magnetic field in the detection of objects in the ocean.detection,and proposes a method to detect undersea targets by using the ship seismic wave of shallow sea.As a new physics field,the ship seismic wave have important application prospect in the detection of objects in the ocean and torpedo fusee design.In this context,this paper models the simple shallow-water environment and studies the characteristics and propagation laws of the ship seismic wave.Firstly,the equations of fluid motion,structural motion and finite element equations at the fluid-structure interface are established.Through the finite element equation,the geometric model of simple shallow water environment is established.Nonreflective boundary conditions are applied around the numerical model to simulate an infinite sea area,The fluid-structure coupling conditions are applied at the fluid-structure interface to simulate the interaction of seawater and seafloor media.Then the ship seismic wave caused by the point sound source is simulated.The transverse wave,longitudinal wave and Scholte wave are analyzed by extracting the effective data of the seismic wave field.The propagation laws of ship seismic waves in three different seafloor media of bedrock,sandstone and sand are studied.The propagation and attenuation characteristics of the horizontal and vertical components of the seabed seismic wave in the horizontal direction and below the interface in the seabed interface are analyzed respectively.The results show that at the fluid-structure interface,the longitudinal wave propagates most rapidly in each wave train,and its amplitude decays by1/r~2 as the distance increases.The transverse wave propagation velocity is between the longitudinal wave and the Scholte wave,the amplitude is also decays by1/r~2.The Scholte wave propagates the slowest in each wave train,and its trajectory of the particle is an inverse ellipse in the depth direction.At the interface,as the horizontal distance increases,the Scholte wave amplitude attenuates by 1/(?);at the interface In the vertical direction,Scholte waves decay exponentially.Therefore,the Scholte wave decays slowly among the three waves,which proves that the Scholte wave has good detection performance in underwater target detection.Finally,through the seismic wave propagation experiment,the attenuation law of seismic waves is verified.