Presentazioni e Articoli Tecnici

Traffic noise pollution has represented a significant challenge for modern societies, requiring the development of innovative noise mitigation strategies. In the last decades, intensive research has been developed into the design and evaluation of noise barriers but there still lacks a simultaneous proper air ventilation for a comfortable environment and lower visual impact. This study presents a comprehensive numerical investigation into the design and performance of ventilated acoustic metamaterial noise barriers to mitigate urban noise while maintaining adequate ventilation. Considering the recent advancements in acoustic metamaterials and computational modeling techniques, we model the design and numerically investigate the periodically arranged noise barriers in the open air which will also allow ventilation. To address this problem, we used COMSOL Multiphysics software to design and analyze the performance of noise barriers numerically. The approach involved modeling a unit cell of noise barriers placed periodically in outdoor environments to facilitate both noise attenuation and ventilation. The finite element approach was used to model the barrier unit cell design, focusing on the numerical calculation of the unit cell sound transmission loss (STL). In our work, we utilized the Pressure Acoustics Module to simulate and analyze the acoustic bandgap frequencies of the metamaterial barriers. Additionally, we used Narrow Region Acoustics which was referenced to model for viscous and thermal boundary-layer-induced losses in channels and ducts of constant cross-section. We used COMSOL's built-in artificial domain Perfectly Matched Layers (PML) to simulate the effect of an infinite domain and absorb outgoing waves to prevent artificial reflections at the boundaries of the computational domain. Periodic boundary conditions (PBC) and Floquet periodicity are used to model unit cells as infinitely repeating structures. For performance analysis, a finite-element approach has been applied to model the design of the barrier, and the Sound Transmission Loss (STL) of the unit cell has been computed numerically. To validate STL and study bandgaps, dispersion curves have been generated for the unit cells with varying configurations. A parametric analysis is also carried out to investigate the effects of the unit cell’s geometric size and the acoustic incident angle on the effectiveness of noise reduction. Within the mid-range of frequencies, sound waves have been attenuated without disturbing the airflow for ventilation. Finally, evaluating the effect of the finite size of the noise barrier on the STL, highlights how in-situ performance may vary as compared to the predicted performance in idealized infinite conditions.

We gratefully acknowledge the European Commission for its support of the Marie Sklodowska Curie program through the Horizon Europe DN METAVISION project (GA 101072415)