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Sonic boom reflection over urban areas.
Didier Dragna1, Ariane Emmanuelli1, Sébastien Ollivier1
1Laboratoire de Mécanique des Fluides et d'Acoustique, Université de Lyon, Ecole Centrale de Lyon, INSA Lyon, Université Claude Bernard Lyon I, CNRS, UMR 5509, 36 Avenue Guy de Collongue, F-69134, Ecully, France.
The Journal of the Acoustical Society of America
|December 31, 2022
Summary
Sonic boom propagation in urban areas shows variable noise levels depending on city geometry. While median noise levels are similar to flat ground, canyon resonance causes significant low-frequency oscillations.
Area of Science:
- Acoustics
- Urban Meteorology
- Computational Fluid Dynamics
Background:
- Sonic boom propagation is complex, especially in urban environments.
- Urban geometry significantly influences acoustic wave propagation.
- Understanding these effects is crucial for noise mitigation.
Purpose of the Study:
- To investigate sonic boom propagation over various urban geometries.
- To analyze the impact of urban canyon aspect ratio on boom characteristics.
- To assess noise levels and resonant phenomena in urban soundscapes.
Main Methods:
- Numerical simulations using Euler equations.
- Modeling of classical N-wave and low-boom waves.
- Analysis of ten urban geometries based on local climate zones.
Main Results:
- Noise levels and peak pressure vary significantly in compact urban canyons (large aspect ratio).
- Open urban canyons (small aspect ratio) show propagation similar to isolated buildings.
- Median perceived noise levels are close to flat ground values, with greater variation in open geometries.
- Low-frequency oscillations due to canyon resonance are observed in all geometries.
Conclusions:
- Urban geometry critically affects sonic boom characteristics and variability.
- Canyon resonance introduces significant low-frequency acoustic components.
- Further research into urban acoustic environments is warranted.
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