Unsteady cavitating flow around the bluff body widely existed in practical engineering fields. This paper aims to investigate the physics involved in the multi-scale cavitating flow in the wake of a wedge-shaped bluff body, with special emphasis on the bubble effects. Numerical simulation is conducted using the traditional Eulerian-Eulerian (E-E) and newly developed Eulerian-Lagrangian (E-L) methods in OpenFOAM. It is found that, compared with the experimental results, the E-L method can predict more accurate cavitation characteristics than the E-E method due to the contribution of discrete bubbles. Bubbles can significantly influence the behaviors of the multi-scale cavitating flow. Specially, analysis of pressure fluctuations indicates that the bubbles induce a stronger power spectral density in the middle- and high-frequency regions. With the bubble effects considered, the vortex structure is stretched and more extensive in the near wake regions. The strength of time-averaged vorticity distribution decreases in the far wake region. Further analysis of the vortex transport equation shows that bubble dynamics significantly increase the intensity of the stretching term by enhancing the spanwise velocity fluctuations. The intensity of the baroclinic torque term predicted by the E-L method is higher than that by the E-E method near the center line due to the influence of bubbles. On the other hand, the analysis of turbulent kinetic energy distribution indicates that bubbles can induce turbulence by increasing cross-stream velocity fluctuations. The increment of the shear Reynold stress, , suggests that the bubbles intensify the coupling between the streamwise and cross-stream velocity fluctuations.

中文翻译：

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气泡动力对钝体尾流多尺度空化流特性影响的数值计算

钝体周围的非定常空化流在实际工程领域中广泛存在。本文旨在研究楔形钝体尾流中多尺度空化流所涉及的物理原理，特别强调气泡效应。数值模拟采用传统的欧拉-欧拉（EE）方法和OpenFOAM中新开发的欧拉-拉格朗日（EL）方法进行。与实验结果相比发现，由于离散气泡的贡献，EL方法能够比EE方法更准确地预测空化特性。气泡可以显着影响多尺度空化流的行为。特别是，压力波动分析表明，气泡在中高频区域引起更强的功率谱密度。考虑到气泡效应，涡流​​结构在近尾流区域被拉伸且更广泛。远尾流区域时均涡度分布强度减弱。对涡流输运方程的进一步分析表明，气泡动力学通过增强展向速度波动显着增加了拉伸项的强度。由于气泡的影响，在中心线附近，EL方法预测的斜压扭矩项的强度高于EE方法。另一方面，对湍流动能分布的分析表明，气泡可以通过增加横流速度脉动来诱发湍流。雷诺剪切应力 的增加表明气泡增强了流向和横流速度波动之间的耦合。