Sonic boom reflection over an isolated building and multiple buildings

Area of Science:

• Acoustics
• Computational Fluid Dynamics
• Urban Aerodynamics

Background:

• Sonic booms generated by supersonic aircraft can cause noise pollution.
• Understanding sonic boom propagation in urban environments is crucial for mitigating noise impacts.

Purpose of the Study:

• To investigate sonic boom reflection and propagation over isolated and multiple buildings.
• To analyze the effects of urban geometry on sonic boom waveforms and perceived noise.

Main Methods:

• Numerical simulations using high-order finite-difference techniques to solve two-dimensional Euler equations.
• Analysis of pressure waveforms and perceived noise for different urban geometries (isolated building, two buildings, periodic buildings).
• Consideration of two sonic boom waves: classical N-wave and low-boom wave.

Main Results:

• Building influence creates illuminated and shadow regions, dependent on building height and Mach number.
• Low-frequency oscillations and resonances occur in street canyons, influenced by street width and boom frequency.
• Waveform duration increases with multiple buildings due to diffraction and canyon resonances.

Conclusions:

• Urban geometry significantly alters sonic boom characteristics, affecting pressure waveforms and noise perception.
• Low-frequency oscillations in street canyons have minimal impact on perceived noise despite their amplitude.
• Noise variations are moderate in wide streets but become noticeable in narrower urban canyons.