On the effect of the dispersion error when updating acoustic models

In the frame of predicting acoustic pressure fields by means of numerical simulations, many tools are already available, making mostly use of the finite or boundary element techniques.In order to get simulated acoustic pressure fields closer to the reality, updating techniques can be used. Particularly, one focuses on a validation method based on the constitutive law error (CLE), which was initially proposed by P. Ladevèze [New Advances in Adaptative Computational Methods in Mechanics, Elsevier, 1998, pp. 135–151] in structural dynamics, and was recently applied to acoustics [V. Decouvreur et al., in: H. Mang, F. Rammerstorfer, J. Eberhardsteiner (Eds.), WCCM V Fifth World Congress on Computational Mechanics, Vienna, Austria, Vienna University of Technology, 2002, ISBN 3-9501554-0-6]. These works use the FEM as numerical approximation method. When increasing the frequency, the validation quality decreases, due to the growing discretization error of the linear FEM.Therefore, to diminish the discretization error, another approximation method is used, namely the element-free Galerkin method.A case study is presented where the discretization error is controlled and the effects on the updating parameters (the admittance coefficients) is evaluated.Comparing the results coming from the validation when using both FEM and EFGM shows that a numerical method with robust frequency behaviour is more suited for updating setups with highly frequency dependent parameters.