Transient acoustic radiation from impulsively accelerated bodies by the finite element method

Bodies under impulsive motion, immersed in an infinite acoustic fluid, seve rely put to test any numerical method for the transient exterior acoustic p roblem. Such problems, in the context of the finite element method (FEM), a re not well studied. FE modeling of such problems requires truncation of th e infinite fluid domain at a certain distance from the structure. The volum e of computation depends upon the extent of this domain as well as the mesh density. The modeling of the fluid truncation boundary is crucial to the e conomy and accuracy of solution and various boundary dampers have been prop osed in the literature for this purpose. The second order damper leads to u nsymmetric boundary matrices and this necessitates the use of an unsymmetri c equation solver for large problems. The present paper demonstrates the us e of FEM with zeroth, first and second order boundary dampers in conjunctio n with an unsymmetric, out of core, banded equation solver for impulsive mo tion problems of rigid bodies in an acoustic fluid. The results compare wel l with those obtained from analytical methods. (C) 2000 Acoustical Society of America. [S0001-4966(00)05003-7].