ASA 124th Meeting New Orleans 1992 October

5aSA4. Fluid--structure interaction studies: Scattering from simple submerged shells using scattering holography.

Earl G. Williams

Naval Res. Lab., Washington, DC 20375

Recently developed at NRL, scattering holography provides the surface velocity at thousands of points on shells excited by an external plane wave. This measurement capability allows for detailed studies of the mechanisms of scattering at the surface of finite cylindrical shells. Time-domain wave-vector filtering is applied to data from a simple shell above a ka of 2.0 in order to study the interaction between the surface and the fluid. In particular, regions of the surface that act as secondary sources, scattering to the far field, are identified using supersonic imaging techniques. Also, results show the generation of subsonic waves on the shell, along with the expected supersonic trace-matched waves. The regions where the fluid and structure interact to produce these subsonic waves will be discussed, along with details of wave propagation on the shell. [Work supported by ONR.]