This paper presents a new time-domain iteration method for computing multifrequency scattering waves from underwater obstacles. The equations are expressed in some forms relative to the retarded time, and the solution of scattering potential can be computed by an iteration process in which the boundary condition on each panel is naturally satisfied. Thus, the present method can treat the scattering problem of geometries with multiple sharp edges. In addition, the numerical inaccuracy due to time interpolation is minimized by using a Fourier series, and the results can robustly converge to correct values by setting zero initial scattering potentials. Several cases of a half sphere in different frequency ranges and one of multifrequency were tested by the present method. The results of all these cases agree with those reached by a frequency-domain boundary element method (BEM). In addition, a case with multiple sharp edges is also tested. The converged results can be obtained by the present method, but not by the BEM. Moreover, the present method is more computationally efficient, especially for the multifrequency case.
