THE BOUNDARY COLLOCATION METHOD WITH MESHLESS CONCEPT FOR ACOUSTIC EIGENANALYSIS OF TWO-DIMENSIONAL CAVITIES USING RADIAL BASIS FUNCTION

In this paper, a meshless method for the acoustic eigenfrequencies using radial basis function (RBF) is proposed. The coefficients of influence matrices are easily determined by the two-point functions. In determining the diagonal elements of the influence matrices, two techniques, limiting approach and invariant method, are employed. Based on the RBF in the imaginary-part kernel, the method results in spurious eigenvalues which can be separated by using the singular value decomposition (SVD) technique in conjunction with the Fredholm alternative theorem. To understand why the spurious eigenvalues occur, analytical study in the discrete system by discretizing the circular boundary is conducted by using circulants. By using the SVD updating terms and documents, the true and spurious eigensolutions can be extracted out respectively. Several examples are demonstrated to see the validity of the present method.