SIMULATION OF ORGAN PIPES' ACOUSTIC BEHAVIOR BY MEANS OF VARIOUS NUMERICAL TECHNIQUES
Péter Rucz, Fülöp Augusztinovicz, Péter Fiala · 2009
The sound generation of an organ pipe is a very complex physical process, since the acoustical phenomena take place coupled with fluid flow effects. Even so, by modeling the organ pipe merely as an acoustic resonator, one can predict several key parameters of the sounding with sufficient accuracy. As these parameters are highly affected by even small changes of the pipe’s geometry, the resolution of the numeric model should be adequately fine, which means that computational time and effort will raise enormously. The aim of our work is to develop a simulation program, which provides the chance to accurately predict acoustic properties of organ pipes. At the same time, the obtained results can serve as guidelines for scaling and intonating the pipes. Taking into consideration that an organ consists of thousands of pipes, an efficient simulation method would greatly aid the work of organ builders, by speeding up the industrial procedure of organ fabrication and intonation. Int he course of the work reported herein we modeled organ pipes by means of various numerical techniques (such as FEM, BEM, coupled FEM/BEM, etc.). Commercial and self-developed software packages were used and the obtained data were compared analytic solutions and measurement results. It was shown that by using these techniques one can approximate key acoustic parameters of the pipe. We have also examined, how certain approximations and neglects can affect the accuracy of simulation.