Calculation of the scattering coefficient of sound diffusers using an improved boundary meshless method

This paper develops an improved boundary meshless method combining the boundary integral equation approach and the meshless method to predict the scattering coefficients. It is applicable to the finite surface with arbitrarily shaped profile. Compared with the traditional BEM, the improved method gives a different simulation model where the diffuser is considered to be attached on an infinite rigid baffle. Based on the model, the integral equation which has unique solution for all frequencies is derived. The solid angle which closely relates with the shape of the diffuser is also involved in the integral equation to give more complete simulation on the geometry of the diffuser. In addition, the system equation for calculating the sound pressure is solved using meshless method, which is beneficial to improve the accuracy on simulating the curved surface. Numerical verifications demonstrate that the improved method is valid for calculating the directional scattering coefficient. Especially, the improved method has better accuracy on simulations for grazing incident waves than the traditional method. The effectiveness of the improved method in calculating the random-incidence scattering coefficient is also validated, where the improved method gives closer results with the measurement than the traditional method.