| A multimodal processing approach is obtained to solve eigenvalues and eigenfunctions in the range-dependent ocean waveguide.Root-finding problem of the transcendental equation is transferred to the decomposing of expansion coefficient matrix which avoids the weakness of low efficiency as well as root-losing.This method achieves eigenvalues and eigenfunctions with the order of modes.Theory derivation is given in both cylindrical coordinate and Cartesian coordinate.Numerical calculation and validation is conducted in isovelocity,sound profile and double layer waveguide.In addition,sound propagation of ocean waveguide is derived based on multimodal processing and the coupled mode theory which is based on step calculation.Propagator matrix of acoustic pressure is replaced with that of acoustic admittance which is always robust.This approach increases the velocity and stability of calculation in long step calculation of long distance waveguide.Numerical simulations prove that transmission loss can be solved correctly in range-independent as well as range-dependent waveguide.Comparison between this method and COUPLE07 program proves the advantages of admittance propagator matrix in calculation speed and precision.Thus,this thesis supplies a new approach to analyze the sound propagation in ocean waveguide. |
