Numerical Simulation on Acoustic Scattering Characteristics of Targets Buried in Fluctuating Seabed

The acoustic scattering of buried elastic target under the bistatic condition is numerically calculated with the finite element method(FEM) on the COMSOL multi-physical field platform. A fluctuating seabed model is established by Gaussian spectrum method, and then the effects of fluctuation height, correlation length, grazing angle and other parameters on the acoustic characteristic of buried targets are obtained. The results show that the echo-to-reverberation ratio of the bistatic is fluctuant when sound enters in single direction while is received on a multi-point linear array. That is, for flat or gently fluctuating seabed, the forward waveform oscillates violently and presents quasi-periodicity, but the regularity of the echo-to-reverberation ratio fluctuation gradually disappears with the increase of seabed roughness. When a sound wave irradiates the seabed vertically, the variation of the correlation length of seabed fluctuation has a significant influence on the Rayleigh variance of the scattering energy, but has little effect on Rayleigh mean. If a sound wave enters obliquely, the correlation length and fluctuation height are the main factors affecting the Rayleigh variance and mean value. These results may provide a reference for acoustic detection of buried targets in seabed.