Martin E. Pace
Theodore W. L. Huskey
Steven R. Baker
Phys. Dept., Naval Postgraduate School, Monterey, CA 93943-5000
Steven G. Kargl
Univ. of Washington, Seattle, WS 98105
Raymond Lim
Coastal Systems Station, Panama City, FL 32407-7001
Measurements were made of the bistatic scattering of underwater sound from
a porous solid sphere. Two sample spheres were employed composed of bonded
glass beads of 100- and 500-micron nominal grain diameter, respectively. The
diameter of each sphere was approximately 6.8 cm. The scattering into the
rearward hemisphere was measured over the frequency range 13 to 150 kHz,
corresponding to values of ka from approximately 2 to 20. Over this frequency
range the viscous penetration depth varies from approximately 5.0 to 1.5
microns, so that the water in the pores can move freely. The experimental
results were compared to numerical computations based on a theoretical Biot
model [S. G. Kargl and R. Lim,