Effect of soft outer lining in pentafurcated duct

Abstract

4This paper describes the diffraction of the lowest plane wave prop-5 agating out of the opening of a semi-infinite hard duct which is sym-6 metrically placed inside an infinite soft duct. The whole system forms 7 a pentafurcated waveguide whose solution is given by eigenfunction ex-8 pansion method. Same method has been used to validate the results 9 of a trifurcated duct problem previously tackled by using the standard 10 Wiener-Hopf technique. Some graphical results showing the influence of 11 waveguide spacing on the reflection coefficient are presented. We com-12 pared our results with the related existing work. We observed that the 13 accumulative value of reflection for current pentafurcated duct is 1375.1 14 which is greater among the related trifurcated and existing pentafurcated 15 ducts. Hence the soft lining on outer plates gives better results to atten-16 uate the unwanted noise. These problems have application in acoustics.

Mode-Matching Analysis of Acoustic Wave Propagation along a Rigid Coaxial Pipe with an Internal Impedance Loading

“…One of the most effective methods is the Mode-Matching or eigenfunction expansion technique, which is based on representing the unknown fields in terms of an infinite sum of orthogonal functions in the individual regions and then matching them across the boundaries between these regions. This method has been applied in many papers [9][10][11][12][13] and give accurate results.…”