NUMERICAL APPLICATION OF NONUNIFORM PSEUDO-SPECTRAL TIME-DOMAIN (PSTD) METHOD FOR ACOUSTIC SCATTERING ON RANDOMLY ROUGH OCEAN SURFACE

Abstract

The conventional pseudo-spectral time-domain (PSTD) method, using the Fourier transform which evaluates the spatial derivative of the wave equation, is an efficient technique by reason that its spatial sampling rate needs only 2 grids per wavelength. The uniform PSTD, however, is required to have more grids in case of irregular boundary in order to satisfy the numerical stability conditions. If nonuniform spatial gridding can be applied for this case, the limitation can be overcome and the numerical calculation should be more efficient. Novel nonuniform PSTD model [Liu et al, Microwave Opt Tech Lett 48, No 12, 2367-2372 (2006)] which evaluates the EM wave propagation simply by transforming the nonuniform space into uniform space using grid interpolation has been developed. In this paper, this method is used to solve the acoustic wave equation and is applied to the scattering on the rough ocean surface. The numerical results in uniform and nonuniform spatial domain are compared in terms of their accuracy and efficiency.