EDITORIAL: SPECIAL ISSUE "EFFICIENT NUMERICAL METHODS"

Abstract

Between September 19th and 23rd, 2005, the International Conference of Theoretical and Computational Acoustics (ICTCA) took place in Hangzhou, Zhejing, China. Greater Hangzhou is a beautiful place south-west of Shanghai located on the delta of river Qiantang (Hangzhou Wan). Prof. Ding Lee, Editor-in-Chief of JCA and Honorary Chair of ICTCA 2005, had been living there before he moved to the USA. It was Prof. Lee, who again encouraged us to invite scientists to contribute papers for a new special issue of this journal. Following his advice, we decided to collect papers from participants of our session at the ICTCA conference and from researchers working on related topics. Altogether we received fifteen scientific papers. Because of this strong interest it was decided to split these papers into two special issues. This is the first part and it starts with a paper by D. Givoli et al. D. Givoli was one of the two key note speakers at ICTCA 2005. His research activities on absorbing boundary condition as well as on Dirichlet-to-Neumann operators are leading guides for the treatment of exterior problems. Then, in a contribution on a fluid-structure interaction written by N. J. Kessissoglou et al. the application of the finite element and the boundary element method to the lower frequency range are combined. The authors are extending this method towards higher frequencies and larger structures, such as submarines. Fourier Acoustics or Near-Field Acoustic Holography (NAH ), as it is also called, has been of interest to researchers for the last two or two and a half decades. It is nowadays one of the tools to identify sound sources or so-called hot spots on vibrating structures; in other words: sound source reconstruction. The current research of Sung-Il Ki et al. focuses on the reduction of the measurement effort and costs by means of the implementation of additional rigid reflectors in the sound field. The following two papers treat inverse acoustics problems as well. R. Anderssohn et al. present an identification method to obtain the complex boundary or wall admittance, whereas Sean Wu et al. suggest a new alternative integral-formulation for the prediction of acoustic fields in exterior as well as interior regions. A contribution to the wide field of scattering phenomena has been received from L. Hervella-Nieto et al., who applied the Perfectley Matched Layers (PML), introduced by Berenger in 1994 to simulate an infinite domain for electromagnetic fields, to time harmonic dissipative acoustics problems.