Characteristic analysis of scattering field in two-layer media by Green’s function

Abstract The problem of three-dimensional (3D) acoustic scattering in complicated medium has been of considerable interest to researchers for many years. An ultrasonic scattered field calculating technique is proposed to study the scattering echo from strongly scattered materials in a two-layer medium. Firstly, with the high frequency stationary phase method, the Green's function of two-layer fluid media is derived. And then based on the idea of integral equation discretization, the Green’s function method is extended to two-layer fluid media to get the scattering field expression of defects in complicated medium. With this method, the scattering field of 3D defect in a two-layer medium is calculated and the characteristics of received echoes are studied. The results show that this method is able to solve the scattering P wave field of 3D defect with arbitrary shape at any scattering intensity in two-layer media. Considering the circumstance of water-immersion ultrasonic non-destructive test(NDT), the scattering sound field characteristics of different types of defects are analyzed by simulation, which will help to optimize the detection scheme and corresponding imaging method in practice, so as to improve the detection quality.