Genetic algorithms: A global search tool to find optimal equivalent source sets

The equivalent source method (ESM) is known as an attractive alternative to the classical boundary element or finite element methods to solve acoustic scattering or radiation problems, mainly because of its straightforward formulation and low computational cost. However, since the quality of the ESM solutions depends strongly on the position of the sources, the lack of general rules for its determination represents a disadvantage to the user. In the present paper, it is shown that a combination of ESM with a specific genetic algorithm can actually remove this disadvantage by providing, given a number of monopoles, their ‘optimal’ localization and complex source strengths. The method is applied to three-dimensional scattering problems in which different body aspect ratios and wave incidence angles are considered. It is shown that the developed technique permits a good reconstitution of the pressure field by using very few monopoles. The accuracy of the solution is also compared with that provided by the multiple-multipole expansion technique.