The frequency averaged normal-derivative integral equation to predict frequency averaged quadratic pressure radiated from structures

Frequency averaged normal-derivative Helmholtz integral equation is proposed to get robust predictions of the frequency averaged quadratic pressure (FAQP) radiated from the structures at medium and high frequencies. The non-uniqueness problem of frequency averaged Helmholtz integral equation and frequency averaged normal-derivative Helmholtz integral equation is overcome by the coupling method combining these two integral equations. The numerical examples are given to demonstrate the versatility of the frequency averaged normal-derivative Helmholtz integral equation and the coupling method.