Motivations and Methods for Developing Nonlinear Near-field Acoustic Holography

Understanding the acoustic field radiated by finite-amplitude sources such as rockets and jets can be important for assessing the impact on involved structures and surrounding communities. Near-field acoustic holography techniques, based on linear equations, do not account for nonlinear behavior. A nonlinear study of the acoustic near-field is described using the general time domain algorithm. This algorithm accounts for all nonlinear phenomena involved. Nonlinear metrics, the bispectrum and Howell-Morfey nonlinearity indicator are being used to quantify the amount of nonlinear interactions occurring in the near-field. Analysis using these metrics is shown