Numerical Modeling using the Nonlinear Progressive Wave
Equation (NPE)
Outdoor
Sound Propagation
| In the following example, a realistic
range-independant sound speed profile of the atmosphere is used.
The acoustic field is initialised at 5km-altitude by a 0.1Hz source
pulse (single-cycle sine wave) modulated by Gaussian envelopes in
depth and in range. Figures 8.a and 8.b represent the spatial moving frame following the pulse respectively for linear and nonlinear acoustic propagation. Here, the linear case is simply computed with the regular NPE by using a low initial Mach number. The signal waveform at 5km-altitude is also represented during propagation over 1000km-range. |
Fig. 8.a : Linear acoustic propagation (a low amplitude source (Ma=0.00001) is used in the NPE model)
Fig. 8.b : Nonlinear acoustic propagation (a high amplitude source (Ma=0.05) is used in the NPE model)