Accession Number : AD0740498

Title :   Finite-Amplitude Sound Propagation in the Farfield of Nonuniform Sources (I). The Diffraction of N Waves by a Circular Aperture in a Plane Baffle (II),

Corporate Author : TEXAS UNIV AUSTIN APPLIED RESEARCH LABS

Personal Author(s) : Lockwood,James C.

Report Date : JUL 1971

Pagination or Media Count : 167

Abstract : In part 1, a solution for the farfield propagation of finite-amplitude waves from nonuniform sources is presented. This solution was obtained by applying the method of multiple scales to solve a second-order, lossless, nonlinear wave equation. The solution represents a generalization of the solution Earnshaw gave for plane waves. In part 2, a solution of the linear wave equation is presented for the diffraction of plane N waves by a circular aperture in a plane baffle. Analytical results are obtained. Because of their complexity, a computer has been used to draw the waveforms. For the case when the observation point is in the beam, the observed waveform is composed of the incident signal plus a diffracted signal. The results show that as the observation point is moved off the axis, the diffracted wave quickly degrades to a low-level signal because of the reduced coherence of the signals from the aperture edge. The theoretical results, modified to apply to an incident spherical wave, agree very well with experimental results obtained by using a spark-produced N wave incident on an aperture. (Author)

Descriptors :   (*UNDERWATER SOUND, DIFFRACTION), BOUNDARY VALUE PROBLEMS, WAVE FUNCTIONS, SHOCK WAVES, PARTIAL DIFFERENTIAL EQUATIONS, PERTURBATION THEORY, APPROXIMATION(MATHEMATICS), PISTONS, FLUID FLOW, VISCOSITY, CONDUCTION(HEAT TRANSFER), THESES, COMPUTER PROGRAMS

Subject Categories : Acoustic Detection and Detectors
      Acoustics

Distribution Statement : APPROVED FOR PUBLIC RELEASE