Download or read book Acoustical Effects of a Large Ridge on Low-Frequency Sound Propagation in Stationary and Moving Atmospheres written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-06-28 with total page 30 pages. Available in PDF, EPUB and Kindle. Book excerpt: The effects of a ridge on a low-frequency acoustic propagation in quiescent and windy atmospheres are investigated using a parabolic approximation. A logarithmic wind-speed profile, commonly employed to model atmospheric wind currents, is modified and used to model two-dimensional atmospheric flow over a triangularly-shaped hill. The parabolic equation is solved using an implicit finite-difference algorithm. Several examples are examined to determine the combined effects of source-ridge distance, ridge dimensions, wind-speed profile, and CW source frequency on the received acoustic field. Robertson, J. S. and Jacobson, M. J. and Siegmann, W. L. and Santandrea, D. P. Unspecified Center NAG1-929...