High-Angle Formulation for the Nonlinear Progressive-wave Equation (NPE) Model
Rept. for Oct 96-Jun 97
NAVAL RESEARCH LAB WASHINGTON DC ACOUSTICS SYSTEMS BRANCH
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The Nonlinear Progressive-wave Equation NPE model has been reformulated for wider propagation angle accuracy. The wide-angle NPE results from range-integrating the second-order time domain nonlinear wave equation rather than reducing it to a one-way equation as in the original NPE. The numerical implementation of the second-order NPE retains two time levels rather than one. The resulting model is referred to as NPE2. Benchmark tests reveal that root mean square rms errors in the model are reduced by a factor of 10 for moderately high propagation angles as compared to similar tests of the first-order NPE.