Abstract
Acoustic propagation in the atmosphere near the Earth’s surface at grazing incidence is influenced by ground impedance. Consequently, numerical simulations must use an impedance ground boundary condition in order to accurately predict ground effects associated with grazing incidence. A mixed Fourier transform method for impedance boundary conditions has been developed for parabolic approaches by the electromagnetics community. Here, the mixed Fourier transform method is adapted and validated for acoustic wave propagation. The one-way solution of the Helmholtz equation is computed with a modified angular spectrum approach to account for a locally reacting surface using a mixed Fourier transform in the vertical direction. Numerical simulations are presented that focus on sonic boom propagation near the ground in the shadow zone. The simulations demonstrate the utility of the mixed Fourier transform method to account for ground impedance effects that are ignored by ray theory-based propagation codes. Consequently, the method extends sonic boom prediction to the lateral cutoff and shadow zone regions. [This research is supported by the Commercial Supersonic Technology Project of the National Aeronautics and Space Administration under Grant No. 80NSSC19K1685.]
Published Version
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call