2aPA6. Computer analysis of the resonant scattering of sound by a bubbly fluid encapsulated by a submerged spherical shell.
Session: Tuesday Morning, June 17
Author: Murray S. Korman Location: Dept. of Phys., U. S. Naval Acad., Annapolis, MD 21402 Author: Scott R. Swain Location: College of William and Mary, Williamsburg, VA 23185 Author: Lawrence A. Crum Location: Univ. of Washington, Seattle, WA 98105
The theoretical results for the resonant backscattering form factor f
((theta)=(pi),k) versus wave number k for scattering from a submerged elastic
shell filled with a bubbly fluid are presented using MATHEMATICA 2.2. The
elastic shell is a castable urethane known as Smooth-On 775 which has a density
of (rho)=1.03 g/cm[sup 3] and longitudinal and shear speeds of c[inf d]~1450
m/s, c[inf s]~70 m/s, respectively. The bubbly fluid is taken to be air bubbles
of uniform radius (50 (mu)m) and spacing, suspended in a host liquid of castor
oil, instead of water, due to its greater viscosity. Resonant scattering is
compared over a range of volume void fractions 0<(beta)<0.01 for the frequency
range 0--20 kHz. Shell inner radius b and thickness t are varied. Results are
compared with an ``ideal'' spherical cloud of bubbly water. Comparisons are
virtually identical for shells where b=5.08 cm and t=0.635 cm. The scattering
theory by Ayres et al. [Int. J. Solids Struct. 23, 937--946 (1987)] is used,
along with the theoretical model by K. W. Commander and A. Prosperetti [J.
Acoust. Soc. Am. 85, 732--746 (1989)] for the complex sound speed and density in
a bubbly medium.