Affiliations: Instituto Politécnico do Rio de Janeiro, IPRJ/UERJ,
Rua Alberto Rangel, s/n, Vila Nova, 28630-050, Nova Friburgo, RJ, Brazil.
Tel.: +55 (22) 2528 8545 poste 315; Fax: +55 (22) 2528 8536; E-mail:
[email protected] | FSAO Virtual Series Department, Ford Motor Company.
E-mail: [email protected]
Abstract: Acoustic intensity is one of the available tools for evaluating
sound radiation from vibrating bodies. Active intensity may, in some
situations, not give a faithful insight about how much energy is in fact
carried into the far field. It was then proposed a new parameter, the
supersonic acoustic intensity, which takes into account only the intensity
generated by components having a smaller wavenumber than the acoustic one.
However, the method is only efective for simple sources, such as plane plates,
cylinders and spheres. This work presents a new technique, based on the
Boundary Elements Method and the Singular Value Decomposition, to compute the
supersonic acoustic intensity for arbitrarily shaped sources. The technique is
based in the Kirchoff-Helmholtz equation in a discretized approach, leading to
a radiation operator that relates the normal velocity on the source's surface
mesh with the pressure at grid points located in the field. Then, the singular
value decomposition technique is set to the radiation operator and a cutoff
criterion is applied to remove non propagating components. Some numerical
examples are presented.
