A computational method of evaluating noncompact sound based on vortex sound theory.

Area of Science:

• Acoustics
• Computational Fluid Dynamics
• Fluid Mechanics

Background:

• Turbulence interacting with noncompact bodies generates sound.
• Previous numerical methods faced challenges with sound generation at computational domain boundaries.
• Extending Howe's vortex sound theory offers a new approach.

Purpose of the Study:

• To numerically investigate sound production by turbulence interacting with a noncompact body.
• To avoid anomalous sound generation in numerical simulations.
• To analyze the acoustic radiation patterns at different frequencies.

Main Methods:

• Formulation in the frequency domain using an extension of vortex sound theory.
• Identification of "scattered" sound sources interacting with the solid surface.
• Application of the boundary element method (BEM) for efficient computation of aeroacoustic Green's functions.

Main Results:

• The boundary element method proved efficient and numerically stable.
• "Scattered" sound sources were localized near the cylinder surface.
• Low-frequency radiation showed dipole-like directivity, while high-frequency radiation exhibited a complex "leaf-like" pattern.

Conclusions:

• The proposed numerical method accurately simulates sound generation by turbulence-body interaction.
• The boundary element method is suitable for noncompact aeroacoustic problems.
• The study highlights significant differences in radiation patterns between low and high frequencies for flow past a cylinder.