Three dimensional modelling of sound absorption in porous asphalt pavement for oblique incident waves
University of Twente
Tuesday 2 june, 2015, 09:00 - 09:20
0.2 Berlin (90)
Tyre-road noise can be reduced by increasing the sound absorption of the pavement. Properties that influence the sound absorption are for example the porosity, the stone size, the type of bitumen and fillers. A ground impedance model can be used to predict the acoustical properties of the pavement. Since a rolling tyre will radiate noise in all directions, the angle of incidence should be accounted for. Also, the sound waves will reflect and scatter on the stones within the pavement, which can be best described by a nonlocally reacting surface. A numerical model has been developed which can predict the three-dimensional sound field in and above the porous asphalt pavement and the absorption coefficient for oblique incident sound waves. The modelling approach is a combination of an analytical and a finite element approach, including both the viscothermal effects and the scattering effects. In this paper the modelling approach is described and simulation results for various three-dimensional stone configurations are given. The developed model can be validated by measurements with a small microphone array, which can measure the absorption coefficient for oblique incident sound waves.
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