An Efficient Method for Acoustic Response Prediction in the Mid-Frequency Range

The paper discusses the application of the Wave Based Method (WBM) for the steady-state acoustic response prediction of a three dimensional cavity up towards the mid-frequency range. Due to its computational efficiency, it is an attractive alternative for the widely accepted element based methods, which is practically restricted to low-frequency applications. Recently, a new wave based prediction technique has been developed which is based on the indirect Trefftz approach. The dynamic pressure field is approximated by wave functions which are exact solutions of the governing Helmholtz equation so that, in contrast with the element based methods,no fine discretization is required. Its enhanced computational efficiency allows the novel technique to handle problems also at higher frequencies. The prediction results are compared with the results obtained by the Boundary Element Method (BEM). For validation purposes, both a simple analytical benchmark problem is considered as well as the three dimensional problem of an irregular enclosure. It is demonstrated that the WBM is computationally more efficient than the BEM in both cases so that the practical frequency limitation for the WBM is much higher than for the BEM.