Sound absorption of two-dimensional rough tube porous materials

In this paper, a theoretical model for predicting the sound absorption performance of two-dimensional rough tube porous materials is established based on the Johnson-Champoux-Allard-Lafarge equivalent fluid model. The shape of the two-dimensional rough tube is approximated by trigonometric functions, and the theoretical expressions of its fluid transport parameters are given, including viscous permeability, thermal permeability, tortuosity, viscous characteristic length, and thermal characteristic length. In addition, the influence of shape factor is considered when calculating the thermal permeability and the viscous characteristic length, and its theoretical expression is given. The theoretical model is verified by a numerical simulation model based on the multi-scale asymptotic method, and good agreement is achieved. Compared with smooth tubes, circumferential rough tubes and axial rough tubes, the two-dimensional rough tubes not only enhance the viscous dissipation effect but also enhance the thermal dissipation effect during the propagation of sound waves, thus, realizing the high-efficiency sound absorption at lower frequencies. This work further develops the sound absorption theory of porous materials considering the roughness effect and enriches the research and design ideas of porous materials.