Apte Dhruv, Ge Mingming, Zhang Guangjian, Coutier-Delgosha Olivier
Kevin T. Crofton Department of Aerospace and Ocean Engineering, Virginia Tech, Blacksburg, 24060, VA, USA.
National Observation and Research Station of Coastal Ecological Environments in Macao, Macao Environmental Research Institute, Faculty of Innovation Engineering, Macau University of Science and Technology, 999078, Macao Special Administrative Region of China.
Ultrason Sonochem. 2024 Dec;111:107122. doi: 10.1016/j.ultsonch.2024.107122. Epub 2024 Oct 30.
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.
水力空化（HC）是一种高度湍流、不稳定的多相流，已在许多处理应用中发挥作用，如废水处理和过程强化，因此需要进行详细研究。本研究的目的是使用数值模拟研究文丘里管内驱动水力空化的机制。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，并将结果与高保真实验数据进行验证。初始二维计算结果表明，虽然URANS模型能够显示不稳定空化，但它们无法再现正确的空化形态，而DES模型能够准确再现空化形态。扩展到三维模拟后，由此产生的涡度收支分析突出了空化-涡相互作用，并显示了速度梯度以及流体元项的增长和收缩相对于产生涡旋的斜压扭矩的主导地位。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。可以观察到，三维DES模拟能够在局部尺度上准确预测雷诺剪应力和湍动能（TKE）等湍流特性的空化-湍流相互作用，强调了湍流的三维效应及其对空化流的影响。然而，数值模拟和实验之间在喉部附近仍然存在显著差异，数值模拟预测此处的空化腔更薄。因此，本研究为模拟水力空化提供了新的见解，并突出了湍流模型开发与水力空化精确模拟之间的瓶颈，为提高建模精度提供参考。
