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Research On Nonlinear Acoustics

Report Number: AMRL TR 67-54
Author: Ablow, Clarence M.
Author: McCulley, Leonard D.
Author: Muller, George M.
Author: Penico, Anthony J.
Author: Rajapakse, Yapa D.
Corporate Author: Stanford Research Inst Menlo Park Calif
Laboratory: Aerospace Medical Research Laboratories
Date of Publication: 1967-12-01
Pages: 188
Contract: AF 33(615)-2234
Project: 7231
Task: 723105
AD Number: AD0667223

The possibility that nonlinear acoustic flows may be represented by spherical progressive waves (in the sense of Courant and Friedrichs) was examined and found to be unlikely. An iterative finite-difference method for the calculation of continuous periodic sphherical flows was developed together with a FORTRAN code, SPHERE, that implements the method. Sample calculations have shown that the code is effective but slow, and several ways for reducing the computation time are suggested. Convergence difficulties in one of the iterative loops were overcome vy the use of a semi-iterative underrelaxation scheme. When applied to linear systems, such semi-iterative schemes were found to be equivalent to a class of summability methods that may be regarded as generalizations of Euler summation.

Lockheed Martin Missiles & Fire Control
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