Sonic Boom Penetration Modeling Via Computational Aeroacoustics

Continuum Dynamics, Inc. (CDI) proposes to develop an advanced modeling capability to assess the environmental impact of sonic boom penetration and its effect upon marine mammals. The approach will utilize Computational Aeroacoustics (CAA) numerical techniques which allow the generation and propagation of sound to be directly calculated from the fundamental governing equations. The proposed effort will be the first use of such techniques in water and will include bubble entrainment and choppy ocean effects. The surface of the ocean will be modeled as a stochastic process with spatial and temporal correlations which can be prescribed at will, a major improvement over previous deterministic studies of sonic boom penetration. Any sonic boom shape may be imposed as a time-dependent boundary condition on any realization of this randomly described surface. The resulting pressure pulse propagating into the ocean will then be calculated by CAA techniques from the governing Euler equations with due account for body forces (e.g. gravity) and bubble entrainment effects. The numerical results can be displayed either as instantaneous ( an or as the time dependent pressure time history at specified observer locations to facilitate assessment of the environmental impact of aircraft or missile operations