Abstract
Since the Morfey-Howell Q/S was proposed as a nonlinearity indicator for propagation of intense broadband noise [AIAA J. 19, 986-992 (1981)], there has been considerable debate as to its meaning and utility. Perhaps the most contentious argument against Q/S is about its validity as a single-point nonlinearity indicator: the importance of nonlinearity is often judged by observing cumulative effects over some propagation distance, whereas Q/S is based on a pressure waveform at a single location. Studies to address these criticisms have emerged over the years, most recently by Reichman et al. [J. Acoust. Soc. Am. 139, 2505-2513 (2016)] in support of Q/S. In this paper, we show that the Burgers equation (from which Q/S was originally derived) can be recast in terms of specific impedance, linear absorption and dispersion coefficients, and normalized quadspectral (Q/S) and cospectral (C/S) densities. The resulting interpretation is that Q/S and C/S represent the additional absorption and dispersion, introduced by the passage of a finite-amplitude wave to the existing linear absorption and dispersion. In other words, a nonlinear wave process alters the apparent material properties of the medium, the extent of which can be used as a single-point indicator of the relative strength of nonlinearity.
| Original language | English |
|---|---|
| Article number | 045003 |
| Journal | Proceedings of Meetings on Acoustics |
| Volume | 29 |
| Issue number | 1 |
| DOIs | |
| Publication status | Published - 2016 Nov 28 |
| Event | 172nd Meeting of the Acoustical Society of America - Honolulu, United States Duration: 2016 Nov 28 → 2016 Dec 2 |
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All Science Journal Classification (ASJC) codes
- Acoustics and Ultrasonics
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In defense of the Morfey-Howell single-point nonlinearity indicator : An impedance-based interpretation. / Ohm, Won Suk; Gee, Kent L.; Reichman, Brent O.
In: Proceedings of Meetings on Acoustics, Vol. 29, No. 1, 045003, 28.11.2016.Research output: Contribution to journal › Conference article
TY - JOUR
T1 - In defense of the Morfey-Howell single-point nonlinearity indicator
T2 - An impedance-based interpretation
AU - Ohm, Won Suk
AU - Gee, Kent L.
AU - Reichman, Brent O.
PY - 2016/11/28
Y1 - 2016/11/28
N2 - Since the Morfey-Howell Q/S was proposed as a nonlinearity indicator for propagation of intense broadband noise [AIAA J. 19, 986-992 (1981)], there has been considerable debate as to its meaning and utility. Perhaps the most contentious argument against Q/S is about its validity as a single-point nonlinearity indicator: the importance of nonlinearity is often judged by observing cumulative effects over some propagation distance, whereas Q/S is based on a pressure waveform at a single location. Studies to address these criticisms have emerged over the years, most recently by Reichman et al. [J. Acoust. Soc. Am. 139, 2505-2513 (2016)] in support of Q/S. In this paper, we show that the Burgers equation (from which Q/S was originally derived) can be recast in terms of specific impedance, linear absorption and dispersion coefficients, and normalized quadspectral (Q/S) and cospectral (C/S) densities. The resulting interpretation is that Q/S and C/S represent the additional absorption and dispersion, introduced by the passage of a finite-amplitude wave to the existing linear absorption and dispersion. In other words, a nonlinear wave process alters the apparent material properties of the medium, the extent of which can be used as a single-point indicator of the relative strength of nonlinearity.
AB - Since the Morfey-Howell Q/S was proposed as a nonlinearity indicator for propagation of intense broadband noise [AIAA J. 19, 986-992 (1981)], there has been considerable debate as to its meaning and utility. Perhaps the most contentious argument against Q/S is about its validity as a single-point nonlinearity indicator: the importance of nonlinearity is often judged by observing cumulative effects over some propagation distance, whereas Q/S is based on a pressure waveform at a single location. Studies to address these criticisms have emerged over the years, most recently by Reichman et al. [J. Acoust. Soc. Am. 139, 2505-2513 (2016)] in support of Q/S. In this paper, we show that the Burgers equation (from which Q/S was originally derived) can be recast in terms of specific impedance, linear absorption and dispersion coefficients, and normalized quadspectral (Q/S) and cospectral (C/S) densities. The resulting interpretation is that Q/S and C/S represent the additional absorption and dispersion, introduced by the passage of a finite-amplitude wave to the existing linear absorption and dispersion. In other words, a nonlinear wave process alters the apparent material properties of the medium, the extent of which can be used as a single-point indicator of the relative strength of nonlinearity.
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U2 - 10.1121/2.0000427
DO - 10.1121/2.0000427
M3 - Conference article
VL - 29
JO - Proceedings of Meetings on Acoustics
JF - Proceedings of Meetings on Acoustics
SN - 1939-800X
IS - 1
M1 - 045003
ER -