Comparison of computer codes for the propagation of sonic boom waveforms through isothermal atmospheres

• Published in: The Journal of the Acoustical Society of America Vol. 100; no. 5; pp. 3017 - 3027
• Main Authors: Cleveland, Robin O., Chambers, James P., Bass, Henry E., Raspet, Richard, Blackstock, David T., Hamilton, Mark F.
• Format: Journal Article
• Language: English
• Published: 01-11-1996
• ISSN: 0001-4966; 1520-8524
• DOI: 10.1121/1.417113

A numerical exercise to compare computer codes for the propagation of sonic booms through idealized atmospheres is reported. Ground waveforms are calculated using four different codes or algorithms: (1) weak shock theory, an analytical prediction; (2) SHOCKN, a mixed time and frequency domain code developed at the University of Mississippi; (3) ZEPHYRUS, another mixed time and frequency code developed at the University of Texas; and (4) THOR, a pure time domain code recently developed at the University of Texas. The codes are described and their differences noted. They are then used to calculate propagation for two different source waveforms, for both a uniform and isothermal (varying density) atmosphere, with and without the presence of molecular relaxation. In all cases the results of THOR, SHOCKN, and ZEPHYRUS are in excellent agreement. Because the weak shock theory algorithm does not include the effect of ordinary absorption, it does not predict the shock structure provided by the other codes. This leads to discrepancies particularly for an atmosphere that includes relaxation effects.