Validating Simulations of Acoustic Propagation in Complex Terrain

Comparing numerical simulations to experimental measurements validates aspects of a finite-difference, time-domain code used to simulate seismic and acoustic propagation. In the experiment, C4 explosions in five distinct locations were used as acoustic sources; the resulting pressure pulse propagated over grassy level terrain. Pressure measurements at multiple locations are compared to the three-dimensional simulations. The metrics used in the comparison were variance in amplitudes and arrival times, differences in the time-domain waveforms, and differences in the frequency response functions. The numerical and experimental waveforms agree qualitatively, but there is a relatively large standard deviation in the difference in peak pressure between experiment and simulation. This is likely due to the high-frequency content of the source, which is not captured in the band-limited numerical model. This will be investigated as the next step in the validation.