ASA 124th Meeting New Orleans 1992 October

5aPAb8. Dissipation effects on finite amplitude waves using a nonlinear progressive wave equation (NPE).

Gee-Pinn James Too

Dept. of Naval Architecture and Marine Eng., Natl. Cheng Kung Univ., Tainan 70101, Taiwan

Jerry H. Ginsberg

Georgia Inst. of Technol., Atlanta, GA 30332

The nonlinear progressive wave equation (NPE) computer code developed by McDonald and Kuperman [J. Acoust. Soc. Am. 81, 1406--1417 (1987)] was used to evaluate a time domain solution in acoustic waveguides. In earlier works, modified versions of NPE [Too and Ginsberg, J. Acoust. Soc. Am. 91, 59--68 (1992)], which omitted dissipation effects, were described to evaluate continuous waves as well as transient waves radiated from a circular baffled piston. In the present work, dissipation due to thermoviscous effect is added to the earlier NPE model by assuming the dissipation effect is small in the transverse direction. Dissipation effects on finite amplitude sound beams are compared with the result of nondissipated NPE model at different locations in the sound field. In addition, dissipation effects on transient waves are shown by including different wavelengths in the initial tone burst of the transient wave. [Work supported by National Science Council and the George W. Woodruff endowment.]