In recent years there are two theories for the acoustic scattering, one is the Singularity Expansion Method (SEM) , the other is the Resonance Scattering Theory (RST). In this paper, relation between these two theorie...In recent years there are two theories for the acoustic scattering, one is the Singularity Expansion Method (SEM) , the other is the Resonance Scattering Theory (RST). In this paper, relation between these two theories was established. For the examples of the acoustic scattering from the solid elastic cylinder and sphere immersed in water, we prove that the RST can be directly derived from the SEM, so that these two theories are equivalent. By use of the Mittag- Leffler theorem we expand the pure elastic scattering wave, which is extracted by isolating the rigid background from the total scattering wave, in an exact resonance expansion. We specially prove that the reradiation efficiency and the resonance width are nearly proportional to the imaginary part of the corresponding pole for most solid objects immersed in water. This shows that the resonance scattering behavious can be entirely determined by the complex frequency poles. For the cases of an aluminum cylinder and a tungsten carbide sphere immersed in water, we calculate the partial-wave form functions by using the new resonance formulae. The results agree with the exact calculation well.展开更多
文摘In recent years there are two theories for the acoustic scattering, one is the Singularity Expansion Method (SEM) , the other is the Resonance Scattering Theory (RST). In this paper, relation between these two theories was established. For the examples of the acoustic scattering from the solid elastic cylinder and sphere immersed in water, we prove that the RST can be directly derived from the SEM, so that these two theories are equivalent. By use of the Mittag- Leffler theorem we expand the pure elastic scattering wave, which is extracted by isolating the rigid background from the total scattering wave, in an exact resonance expansion. We specially prove that the reradiation efficiency and the resonance width are nearly proportional to the imaginary part of the corresponding pole for most solid objects immersed in water. This shows that the resonance scattering behavious can be entirely determined by the complex frequency poles. For the cases of an aluminum cylinder and a tungsten carbide sphere immersed in water, we calculate the partial-wave form functions by using the new resonance formulae. The results agree with the exact calculation well.
