Development of a three-dimensional semi-coherent energy flux propagation model

Abstract

The classic energy flux propagation model integrates an averaged intensity distribution over elevation angle for an azimuthally symmetric waveguide, and the method has also been extended to reincorporate some of the coherence in the mode-sum cross product, producing caustic features and convergence zones. Some ocean environments with asymmetric range-dependent bathymetry and acoustic medium properties can refract the acoustic wave horizontally which N-by-2D models cannot capture due to their assumed symmetry. Fully three-dimensional models can capture horizontal refraction but are typically computationally expensive to execute. Further development and study of the energy flux method is worthwhile since it avoids root-finding, is not a marching solution, and it invokes mode number invariance under the adiabatic modes assumption to map propagation angles and directly integrate the intensity distribution at the receiver location. A first-pass at analytically deriving a generalizable three-dimensional energy flux model was presented previously, and this current study focuses on further analytical development, numerical implementation, and efforts to verify the model using other three-dimensional acoustic propagation models.