Numerical analysis of horn effect reduction on porous pavement

Abstract

Porous pavement is often seen as an effective engineering solution to reduce traffic noise. It works by reducing the horn effect of tire/road noise generation using its acoustic absorbing ability. Sound energy dissipates when it propagates through the porous surface layer due to the viscous and thermal effects resulting from the compression and expansion of air within the micro-structure of pore network. This sound absorption becomes more significant when it comes to horn effect because the multireflection process makes the absorption occur multiple times in sound propagation. Despite the significance of horn effect reduction on porous pavement, research studies on this topic are still limited to date. This paper attempts to investigate the horn effect reduction in a numerical perspective. A brief description of the acoustic characteristics of porous pavement is presented. Representative phenomenological and microstructural models which are capable to derive the acoustic impedance of porous pavement from its volumetric and composition characteristics are introduced. A numerical horn effect measurement model using boundary element method is then developed and validated against experimental results. This model is next used to analyze horn effect reduction on porous pavement. The influence of source position, the directivity of horn effect reduction, as well as the influence of the thickness and porosity of porous layer are examined. The simulation results demonstrate the feasibility of BEM model in the analysis of noise propagation on porous pavement and can provide some in-depth understanding of the horn effect on porous pavement.