On the modelling of reactive silencers with narrow side-branch tubes

This work represents a theoretical study of the sound propagation in a waveguide loaded by an array of flush-mounted narrow side-branch tubes, forming a simple low-frequency reactive silencer. The individual tube-lengths and the distances between the adjacent tubes may vary in order to optimize the transmission loss in a given frequency range. The transmission properties of the silencer are calculated using the transfer matrix method, and the finite element method. A simple heuristic evolutionary algorithm, together with an analytical mathematical model (the transfer matrix method) is employed for the determination of the optimal silencer parameters. The numerical results are validated against the finite element simulation.