Research On Fast Calculation Of Sound Field Based On Parabolic Equation Method

Since the 70's of the last century the parabolic equation theory was introduced into the field of underwater acoustics,after 30 years of development,with its high efficiency of computing and precise calculation precision, the parabolic equation method has become an important means of scientific research and engineering application of acoustic field.However,with the up grading of scientific research and engineering technology,the computation efficiency of the parabolic equation method has become increasingly unable to meet the practical needs of users.The main content of this paper is focused on how to realize the fast calculation of parabolic equation. The methods mentioned not only mean a great value to the parabolic equation theory and the marine scientific research,but also a applicable value for engineering applications.This paper improves the computational efficiency of the parabolic equation method in the following three aspects:(1) Apply perfectly matched layer technology to elastic parabolic model equation:perfectly matched layer method will truncate infinite boundary and simulate infinite radiation conditions more effectively. Numerical simulation results show that with consistent calculation precision, the thickness of perfectly matched layer is far lower than that of artificial absorbing layer, which effectively improves calculating speed;(2) Set up a calculation model of acoustic field parabolic equation with non-uniform grid in the depth direction,apply large-step grid where the medium parameters change slowly and put small-step grid into places with sharp changes,that is, to achieve rapid calculation of parabolic equation method by reducing the grid density. Simulation results show that non-uniform grid parabolic equation method will keep high calculation precision while reducing discrete points in the depth direction.(3) Introduce the parallel computations of related technologies to the parabolic equation method realize the parallel computation of fluid parabolic equation by the parallel solution of three diagonal linear equations,at the same time,approach the computation of broadband frequency elastic parabolic equation via parallel programming model with single program and multiple data streams.Increase the hardware overhead to achieve rapid calculation of parabolic equation method. The efficiency of parallel computing method for parabolic equation through the numerical simulation of the multi-group field is verifed.