ULTRASOUND WAVE-PROPAGATION THROUGH ROUGH INTERFACES - ITERATIVE METHODS

Two iterative methods for the calculation of acoustic transmission thr ough a rough interface between two media are compared. The methods emp loy a continuous version of the conjugate gradient technique. One meth od is based on plane-wave expansions and the other on boundary integra l equations and Green's functions. A preconditioner is presented which improves the convergence for spectra that include evanescent modes. T he methods are compared with regard to computational efficiency, rate of convergence, and residual error. The sound field differences are de termined for a focused ultrasound beam distorted by surfaces having a Gaussian roughness spectrum. The differences are evaluated from the ro ot-mean-square differences on the rough surface and in the focal plane . (C) 1996 Acoustical Society of America.