On the Road to Computational Acoustics
POSEIDON RESEARCH SANTA MONICA CA
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Acousticians have largely overlooked the methods of computationa1 fluid dynamics i.e., the direct numerical integration of the nonsteady, compressible continuity, momentum, and energy equations because of the success of the linearized normal-mode approach and because the numerical viscosity inherent in traditional computational methods damps out acoustic disturbances at an unrealistic rate. The advantage of the computational approach is that it allows inclusion of physical phenomena excluded from the linearized normal-mode approach such as nonlinear convection, non- isentropic losses, and phase change effects. The recent development of SHASTA, a relatively nondiffusive computational method J. P. Boris and D. L. Book, J. Comp. Physics 11, 38-69 1973, has made possible the accurate solutions to acoustics problems. SHASTA is applied to a piston driven shock wave, an acoustic traveling wave, and an acoustic standing wave. The solutions of these problems by other standard numerical schemes are shown for comparison. It is found that only SHASTA is acceptable for all problems considered. As a practical example the computational approach is applied to the acoustic-waveentropy-wave interaction associated with reflections from a choked flow wall.
- Fluid Mechanics