Acoustic scattering by baffled flexible surfaces: The discrete optical theorem

The optical theorem for acoustic scattering by baffled membranes and plates relates the total cross section of the scattered field, the directivity fa ctor in the specular direction. and the energy dissipated by the structure. It is basically a statement of conservation of power. In this paper it is demonstrated that the discrete formulation of these problems, obtained by a Galerkin approximation, exactly satisfies the optical theorem. This discre te relationship holds regardless of the choice of basis functions and the s ize of the truncated system N. Thus, the adherence of the approximate numer ical results to the power conservation law does not necessarily imply its a ccuracy. (C) 2000 Acoustical Society of America. [S0001-4966(00)05103-1].