تحلیل آکوستیک جریان آشفته حول استوانه نوسانی و ثابت در رینولدزهای ۳۰۰۰، ۴۰۰۰ و ۵۰۰۰

Hydroacoustic analysis of three-dimensional turbulent flow around a cylinder in the Reynolds number range of 3000, 4000, and 5000 has been carried out numerically in both stationary and oscillating cases. The cylinder oscillation was applied in the direction perpendicular to the main flow with a frequency of 0.23 Hz and an amplitude of 0.4 m, in order to investigate the effect of external excitation on vortex shedding and sound generation. The simulation was performed using the finite volume method in OpenFOAM, employing the Spalart–Allmaras DDES turbulence model, which combines LES and RANS approaches. Acoustic analysis was conducted based on the Ffowcs-Williams–Hawkings (FW-H) equation, utilizing specified observer points.
The results show that cylinder oscillation increases the vortex shedding frequency. Furthermore, the drag and lift coefficients were examined. According to the Ffowcs-Williams–Hawkings analogy, the increase in acoustic radiation is attributed to the amplification of the dipole component of surface forces on the cylinder. Therefore, the oscillatory motion of the cylinder alters the dominant sound generation mechanism and does not create the classical frequency lock-in between vortex shedding and structural excitation. These findings have significant implications for the design of flow-exposed structures and the reduction of acoustic noise.