Hydrodynamic Cavitation (HC) is a highly turbulent, unsteady, multi-phase flow that has been useful in many processing applications like wastewater treatment and process intensification and hence needs to be studied in detail. The aim of this study is to investigate the mechanisms driving HC inside a Venturi tube using numerical simulations. The numerical simulations are conducted in the form of both two-dimensional (2D) and three-dimensional (3D) simulations using the Detached Eddy Simulation (DES) model database to simulate the cavitation–turbulence interplay, and the results are validated against high-fidelity experimental data. Initial 2D calculation results show that though URANS models are able to show unsteady cavitation, they are unable to reproduce the correct cavity morphology while the DES models reproduce the cavity morphology accurately. After extending to 3D simulations and the resulting vorticity budget analysis highlight the cavitation–vortex interactions and show the domination of velocity gradients and the growth and shrinking of the fluid element terms over the baroclinic torque for vortex production. Finally, localized scale comparisons are conducted to evaluate the model’s ability to simulate the cavitation–turbulence interaction. It is observed that the 3D DES simulations are able to predict accurately the cavitation–turbulence interaction on a localized scale for turbulence properties like Reynolds shear stress and Turbulent Kinetic Energy (TKE), emphasizing the 3D effects of turbulence and their influence on the cavitating flow. However, significant discrepancies continue to exist between the numerical simulations and experiments, near the throat where the numerical simulations predict a thinner cavity. Therefore, this study offers new insights on simulating HC and highlights the bottleneck between turbulence model development and accurate simulations of HC to provide a reference for improving modeling accuracy.

中文翻译：

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文丘里管中流体动力空化三维效应的数值研究


流体动力空化 （HC） 是一种高度湍流、不稳定的多相流，在许多加工应用中很有用，如废水处理和工艺强化，因此需要详细研究。本研究的目的是使用数值模拟研究文丘里管内驱动 HC 的机制。数值模拟以二维 （2D） 和三维 （3D） 模拟的形式进行，使用分离涡模拟 （DES） 模型数据库来模拟空化-湍流相互作用，并根据高保真实验数据验证结果。初步的二维计算结果表明，虽然 URANS 模型能够显示非定常空化，但它们无法再现正确的空腔形态，而 DES 模型则准确再现了空腔形态。在扩展到 3D 仿真和由此产生的涡度预算分析之后，突出了空化-涡流相互作用，并显示了速度梯度的主导地位以及流体单元项在涡流产生的斜压扭矩上的增长和收缩。最后，进行局部尺度比较，以评估模型模拟空化-湍流相互作用的能力。据观察，3D DES 仿真能够在局部尺度上准确预测雷诺剪切应力和湍流动能 （TKE） 等湍流特性的空化-湍流相互作用，强调湍流的 3D 效应及其对空化流的影响。然而，数值模拟和实验之间仍然存在显着差异，在喉部附近，数值模拟预测的腔体更薄。 因此，本研究为湍流模型仿真提供了新的思路，并强调了湍流模型开发与精确仿真 HC 之间的瓶颈，为提高建模精度提供参考。