Numerical Modeling using the Nonlinear Progressive Wave
Equation (NPE)
Nonlinear
Acoustic Propagation in an Ocean Waveguide
| Here is an example of numerical simulation in a shallow-water Pekeris waveguide. The acoustic field is initialised at 100m-depth by a 50Hz narrowband source pulse (5-cycle sine wave). The initial acoustic Mach number is 0.005. The starting field displays a spatial distribution which is modulated by Gaussian envelopes in depth and in range. Figures 3.a and 3.b represent the spatial moving frame following the pulse respectively for linear and nonlinear acoustic propagation. The signal waveform at 100m-depth is also represented during propagation over 200km-range. |
Fig. 3.a : Linear acoustic propagation in shallow water (the nonlinear steepening term of the NPE is removed)
Fig. 3.b : Nonlinear acoustic propagation in shallow water