Numerical investigation of bubble wake properties in the moving liquid with LES model

Wake flow caused by the relative motions between bubble and liquid phase influences bubble motions and enhances turbulent properties in the liquid phase. This phenomenon has been stressed for a better understanding of bubbly flow. In this paper, large eddy simulation (LES) is performed to simulate a single bubble rising in the moving liquid, with volume of fluid (VOF) method to capture the interface movements between bubble and liquid phase. The simulation results are firstly compared with the numerical and experimental data from the literature. A good agreement demonstrated the capability of the employed computational fluid dynamics (CFD) approach to predict turbulent properties in the liquid phase and capture interface movement as well as its induced wake flow. Consequently, the dynamic behaviors of a single bubble rising in the moving liquid were investigated. An ensemble averaged has been employed to evaluate the velocity distribution composed by wake velocity and liquid velocity quantitatively as well as the velocity fluctuations enhanced by bubble motion. Their dependency was also evaluated based on a systematic CFD simulation which covers a wide range of liquid velocity. With comparisons of the single phase flow, the influence from the existence of bubble on turbulent properties was determined. (author)