Meshless FEM-BEM method for computing sound transfer function in enclosed spaces

The finite element method (FEM) or boundary element method (BEM) is usually employed in sound field calculation of a cabin space at lower frequency, but a single method can not satisfy computing requirements of complex structures. These methods have some disadvantages, such as, lack of pre-processing and smoothing processing. Aiming at these problems, here, FEM and BEM were combined into a hybrid algorithm, and then transform it was converted into a meshless algorithm. It was a new approach for a sound prediction problem in enclosed environment. At first, the combined meshless FEM-BEM model was derived, and then the specific details including discretization of differential equations, construction of shape functions, nodal disposal, and were combined integral computing scheme were described. Finally, numerical simulations and tests were conducted to verify this method. The simulation results showed that the results using the proposed method agree well with those using SYSNOISE. The test results showed that the average relative error of each position's sound pressure of a cabin space is less than 5.26%. These results showed that the proposed method not only is applicable for complex problems, but also has a good computation accuracy.