THE SCIENCE AND APPLICATIONS OF ACOUSTICS - H. H. Arnold ...

450 16. UltrasonicsFigure 16.1. Sound absorption per wavelength and velocity dispersion in fluorine at102 ◦ C.In the case of polyatomic gases or mixtures of relaxing diatomic gases, the relaxingmodes can be coupled by vibration-to-vibration exchanges. These multiplerelaxation processes follow the general behavior given by Equations (16.10) and(16.11), but the magnitude of the absorption and dispersion and the associated relaxationfrequencies assumes a different connotation. For this case of the multiplerelaxing internal energy modes, Equations (16.10) and (16.11) are changed intothe following formats:( cαλ) 2 ∑=−πc ∞ j( c) 2 ∑= 1 +c ∞jδ j k s /k ∞ s1 + (ωτ s, j ) 2 (16.12)δ j k s /k ∞ s1 + (ωτ s, j ) 2 (16.13)