Aeroacoustic analysis of a wavy rectangular cylinder

Flow past rectangular cylinders generates complex wake structures, leading to substantial aerodynamic drag and far-field noise, and poses challenges in applications in a wide range of engineering and transportation systems. This study investigates the effects of spanwise wavy corrugations on the aerodynamic and aeroacoustic performance of rectangular cylinders through numerical simulations at a Reynolds number of ReD=2.2×104. Compared with a baseline straight rectangular cylinder, the wavy configuration alters shear-layer evolution, delays the onset of vortex shedding, and redistributes vortical structures in the near wake, resulting in reduced coherence of aerodynamic force fluctuations and enhanced aerodynamic efficiency. These flow modifications also result in pronounced reductions in far-field noise, including attenuation of dominant tonal components, broadband radiation, and secondary harmonic radiation. A detailed source-term analysis, incorporating the divergence of the Lamb vector as a field source, the longitudinal material source, and higher-order kinetic sources, indicates that spanwise waviness enhances energy dissipation and fragments coherent vortical structures. Wall boundary effects further modulate shear-layer and wake dynamics, influencing vortex formation and reattachment behavior. Overall, the results provide a physically consistent interpretation between near-field flow alterations and far-field noise reduction, suggesting that spanwise wavy corrugations offer an effective approach for drag and noise mitigation. This work offers insights for the design of low-noise, aerodynamically efficient rectangular cylinders and contributes to the understanding of flow–structure–acoustic interactions in bluff-body aerodynamics.