Effects of Temperature, Salinity, and Fluid Type on Acoustic Characteristics of Turbulent Flow Around Circular Cylinder

The effects of the temperature, salinity, and fluid type on the acoustic characteristics of turbulent flow around a circular cylinder were numerically investigated for the Reynolds numbers of 2.25 × 10⁴, 4.5 × 10⁴, and 9.0 × 10⁴. Various hybrid methods—Reynolds-averaged Navier–Stokes (RANS) with the Ffowcs Williams and Hawkings (FWH) model, detached-eddy simulation (DES) with FWH, and large-eddy simulation with FWH—were used for the acoustic analyses, and their performances were evaluated by comparing the predicted results with the experimental data. The DES-FWH hybrid method was found to be suitable for the aero- and hydro-acoustic analysis. The hydro-acoustic measurements were performed in a silent circulation channel for the Reynolds number of 2.25 × 10⁴. The results showed that the fluid temperature caused an increase in the overall sound pressure levels (OASPLs) and the maximum sound pressure levels (SPL_T) for the air medium; however, it caused a decrease for the water medium. The salinity had smaller effects on the OASPL and SPL_T compared to the temperature. Moreover, the main peak frequency increased with the air temperature but decreased with the water temperature, and it was nearly constant with the change in the salinity ratio. The SPL_T and OASPL for the water medium were quite higher than those for the air medium.