A hybrid analysis of Mach cutoff noise using nonlinear acoustics and finite-difference time-domain method

This paper proposes a two-dimensional, hybrid analysis method of so-called Mach cutoff noise, which treats boom signature and its disturbance due to collision of the signature with atmospheric turbulence separately. A combination of the augmented Burgers equation analysis and the nonlinear Tricomi equation analysis is applied to the former, while the conventional compact-explicit finite-difference time-domain method is applied to the propagation analysis to the latter. Some numerical experiments were conducted with the method, resulting in the larger Perceived Level at the ground than those by the conventional linear analysis. It was also shown that the Mach cutoff noise on the ground is mostly affected by the incoming boom.