A detailed numerical analysis of the flow field characteristics of vortex acoustic streaming around a cylindrical tube

Abstract

In this study, a detailed numerical analysis was conducted to investigate the vortex acoustic streaming around a cylindrical tube using the Reynolds stress method. The evolution of acoustic streaming structures across a wide range of parameters was investigated, and the general relationships between acoustic streaming intensity and acoustic parameters were summarized. It was discovered that low-frequency and intense sound waves (20 Hz, 149.33 dB) can generate distorted acoustic streaming with an axisymmetric distribution surrounding the cylindrical tube. This acoustic streaming internally evolves into a flow field characterized by jet-like vortices, with near-wall velocities reaching as high as 710 mm/s. On the contrary, high-frequency (5 kHz) acoustic streaming no longer has the characteristic of axisymmetric distribution. The inhomogeneity of the sound field leads to changes in the vortex scale, with near-wall velocities reaching only 1 mm/s. The acoustic streaming vortex outside the cylindrical tube gradually presents different flow field structure changes as sound pressure level and frequency increase. Moreover, the streaming intensity under different acoustic parameters is analyzed using a dimensionless approach. It is found that a specific function relationship between dimensionless acoustic streaming intensity and Strouhal number exists, and the empirical formula is given.