On the anomalously low attenuation of the leaky Rayleigh wave in a fluid-filled cylindrical cavity

It is shown that the dispersive Rayleigh wave propagating around a concave cylindrical surface is substantially less attenuated by fluid loading than the corresponding wave on a flat surface. First, the analytical solution for vertically polarized shear wave scattering from a fluid-filled cylindrical cavity is formulated in the time domain, then the signal of interest is gated out and spectrum analyzed in order to numerically predict the attenuation caused by leakage into the fluid. On a concave surface the ratio of the normal and transverse displacement components produced by the circumferential creeping wave is lower than that of the ordinary Rayleigh wave propagating on a flat surface, which explains the reduced leaky attenuation caused by fluid loading. Experiments were carried out to verify these analytical predictions. The fluid-loading induced semicircumferential loss of the circumferential creeping wave around a cylindrical cavity was found to be in excellent agreement with the experimental measurements over a wide frequency range. © 1998 Acoustical Society of America. @S0001-4966~98!00609-2#