A parallel code for time dependent acoustic scattering involving passive or smart obstacles

A highly parallelizable numerical method to solve three-dimensional time-dependent acoustic obstacle scattering problems involving passive or smart, furtive, realistic obstacles is presented. ‘‘Realistic’’ obstacles have complex geometries, ‘‘passive’’ obstacles do not react by taking an action to pursue a goal when hit by an incoming wave, and ‘‘smart furtive’’ obstacles, when hit by an incoming wave, pursue the goal of being undetectable by circulating a suitable pressure current on their boundaries. Incoming wave packets containing time-harmonic waves of small wavelengths when compared with the characteristic dimension of the obstacles are considered. The features of the computational method proposed to solve these scattering problems that can be exploited in a parallel and/or distributed computing environment are presented. Numerical experi- ments involving a simplified version of the NASA space shuttle are discussed. The websites: http://www.econ.univpm.it/ recchioni/scattering/w12, http://www.econ.univpm.it/recchioni/scattering/w14 contain animations and virtual reality appli- cations showing some numerical experiments relative to the problems studied. A more general reference to the work of some of the authors and of their coworkers in acoustic and electromagnetic scattering is the website: http://www.econ. univpm.it/recchioni/scattering.