WIDE-BAND APPROXIMATION OF THE SOUND FIELD SCATTERED BY AN IMPENETRABLE BODY OF ARBITRARY SHAPE

The scattered field on the boundary of an insonified hard or soft cyli nder of arbitrary shape (Cas) is obtained in approximate manner by usi ng explicit forward scattering solutions of insonified impenetrable ci rcular cylinders (CC) whose radii vary with location on the boundary o f the Cas. This so-called intersecting canonical body approximation (I CBA) is employed in the boundary integral representation in order to d etermine field functions at arbitrary points on or outside the scatter ing body. The approximation is evaluated in the near and farfield zone by comparison with rigorous solutions obtained from a boundary-integr al equation scheme. The ICBA is shown to give results that are of bett er quality in the low frequency and resonance regions and of equivalen t quality in the high frequency region as compared with the approximat e solution deriving from the oft employed Kirchhoff ansatz of the surf ace field. (C) 1996 Academic Press Limited