Ray Tracing Techniques - Derivation and Application to Atmospheric Sound Propagation.
Abstract
It is commonly known that in non-homogeneous media (phase velocity dependent on location) refraction of acoustic signals occurs. Solving the wave equation with variable c is extremely involved and the cases where solutions can be found do not give very much insight into the physical meaning of the problem. The method of ray tracing, the solution of the eikonal equation, readily adapts itself to non-homogeneous media and describes the propagation of wavefronts. It has been used extensively in underwater acoustics but not so much in atmospheric applications. Some reasons for the limited use of ray tracing techniques in outdoor sound propagation are that (1) most acoustic work in recent years has been for underwater applications due to Navy sponsoring, and (2) also very few simultaneous measurements of acoustical and meteorological data have been performed. Atmospheric sound ranging techniques have in the past neglected verticle velocity gradients. Ray tracing is a useful method in studying propagation in air and can be used as an adjustment to sound ranging methods to consider atmospheric variations. Presented here is a derivation of the eikonal equation and its solution with an attempt to give physical reasons for this approach. A computer model of the technique of ray tracing for atmospheric applications (also an eigenray model) has been developed and some results are given using data collected in field measurements. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Jan 01, 1980
- Accession Number
- ADA108626
Entities
People
- S. David Roth
Organizations
- Pennsylvania State University