Backscattering Programs for Spherical Targets,
Abstract
These programs compute the acoustical reflectivity of a sphere in a fluid medium. The programs differ in the allowed physical properties of the spheres. The principal outputs of the programs are plots of reflectivity, R-squared, as a function of size-frequency, ka. The reflectivity is defined as R-squared = (sigma sub b)/(a-squared/4) where sigma sub b is the backscattering cross-section of the sphere, and a-squared/4 is the backscattering cross-section of a completely reflecting sphere of radius a. The variable k is the wavenumber in the medium. These plots may be considered as dimensionless representations of target strength vs. frequency. The conversions are TS = 10 log (R-sqaured times a-squared/4) and f = cKa/2pia with a in meters, c in meters per second and f in kHz. This relation for frequency is such that the product of frequency in kHz and radius in mm is 240 when ka = 1. These programs have been used primarily for low contrast cases (with g and h near one) at relatively low values of ka (less than 10). Some adjustments to the tolerance parameters may be necessary for other cases.
Document Details
- Document Type
- Technical Report
- Publication Date
- Apr 01, 1979
- Accession Number
- ADA081094
Entities
People
- David Standley
- Lawrence Flax
- Richard K. Johnson
Organizations
- Oregon State University