Application of the modal-FE method to the study of open periodic lattices
Résumé
A coupled modal-FE method is presented for the study of sound propagation in urban areas. This method has been successfully applied in previous works for the modeling of irregular street canyons and intersections between perpendicular streets. The main idea is to turn the originally open domain on an equivalent guiding structure. This is done by substituting the openings in the original domain by perfectly matched layers (PML). Then, the process is principally divided in two steps. First, the eigenmodes of the resulting cross-section are obtained using a finite elements (FE) computation. Secondly, these eigenmodes are used into a modal formulation of the wave propagation within the domain. In the present work, we briefly explain the principles of the method and we show its application to the study of open periodic lattices, representing regular distributions of buildings. The periodicity of such a domain is taken into account by implementing periodic boundary conditions in the FE computation of the eigenmodes.