Modeling And Applications Of Three-Dimensional Sound Propagation With High Order Solution

Acoustic propagation modeling is an important subject of underwater acoustics research.At present,most of the commonly used acoustic propagation models are in the form of 2D or N×2D without considering horizontal deflection.The real marine environment is changeable and complex,and due to the inhomogeneity of the seawater medium and boundary conditions,the actual acoustic propagation has 3D effect to a certain extent.Therefore,it is of great significance to establish a 3D acoustic propagation model suitable for the real environment.A 3D acoustic propagation model based on the parabolic equation is developed.With retaining the third-order expansion term,the higher order Taylor approximation of Helmholtz equation is carried out.Then the Split-Step Fourier(SSF)method is applied to calculate the acoustic field step by step recursively.The model is applied to the slope environment and the submesoscale eddy environment to verify its ability to deal with the 3D effect and the actual ocean environment acoustic propagation problem.This paper also discuss the acoustic propagation law when the seabed topography and marine hydrological environment change in 3D space.The main research work is listed as follows:Firstly,the higher order approximation of Helmholtz operator is used and the error analysis is carried out.Taking absolute numerical error and relative phase error as the unified standard,it is quantitatively demonstrated that the higher order approximation method is more accurate.Based on the SSF method,we calculate acoustic field step by step.Secondly,the model was used to calculate the 3D acoustic field in the slope environment.RAM model,horizontal ray theory and image method are used as a contrast.It is verified that the model is able to deal with the 3D deflection effect.Thirdly,3D submesoscale eddy models,including cold eddy and warm eddy,are established in the real topography.With discrete treatment,boundary treatment and absorption layer treatment,the acoustic fields in the cold and warm eddy environment are calculated.It's showed that the model is suitable for calculating acoustic propagation in the submesoscale eddy environment.