Recovery of the location, size, orientation and shape of a rigid cylindrical body from simulated and experimental scattered acoustic field data

Abstract

The Intersecting Canonical Boundary Approximation (ICBA) [T. Scotti A. Wirgin (1995). Shape reconstruction using diffracted waves and canonical solutions Inverse Probs. 11, 1097; A. Wirgin T. Scotti (1996). Wide-band approximation of the sound field scattered by an impenetrable body of arbitrary shape J. Sound Vibr.,194, 537.] is employed as the estimator to recover the location, size, orientation and shape of an acoustically-rigid body from both simulated data obtained from a boundary element code, and real data obtained by means of experiments appealing to audible monochromatic sound as the probe radiation. It is shown, both empirically and theoretically, that the cost functional of the discrepancy between the estimated and measured data exhibits more than one minimum for each measurement point which implies nonuniqueness of boundary identification. The underlying theory by which this nonuniqueness is made evident indicates that the use of scattering data at two or more frequencies makes it possible to reduce the ambiguity of the reconstruction. It is shown that once the nonuniqueness issue is addressed, the quality of the identification is determined by a complex interplay of data and estimator error.