In the present investigation, the LES WALE method along with the Zwart cavitation model is utilised to predict the cavitating flow around a Delft Twist-11 hydrofoil and the numerical results show a reasonable agreement with the experimental data. A novel elucidation is provided to the formation of the U-type structure and the Lumley method is introduced into the numerical simulation which can offer a validation of the simulation. The evolution of the cavity structure, especially the formation and development of U-type structures, was investigated thoroughly with the assistant of the Ω method, the Lamb vector, and the vorticity transport equation (VTE). As a third-generation vortex identification, Ω = 0.52 captures the vortex structure during the cavity evolution exhaustively. The cavitation-vortex interaction impacts the cavity evolution profoundly. The primary weak vortex and the secondary weak vortex both have a significant effect on the cavity shedding and the formation of the U-type structure. Moreover, the stretching action and the vorticity bearing motion described by the Lamb vector divergence clarify the formation of the special cavity structure in depth. In virtue of the mean velocity, Reynolds stresses, Lumley triangle, and Lumley distance, the turbulence characteristics were also investigated carefully. The cavitating motion plays a significant role in the turbulence velocity fluctuation and turbulence anisotropy around a twisted hydrofoil.

中文翻译：

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Delft Twist-11 水翼周围周期性空腔演化和湍流特性的大涡模拟

在本研究中，利用 LES WALE 方法和 Zwart 空化模型来预测 Delft Twist-11 水翼周围的空化流动，数值结果与实验数据显示出合理的一致性。对U型结构的形成进行了新的阐述，并将Lumley方法引入数值模拟中，为模拟提供了验证。借助Ω法、Lamb矢量和涡量输运方程（VTE），深入研究了空腔结构的演化，特别是U型结构的形成和发展。作为第三代涡旋识别，Ω = 0.52 详尽地捕捉了腔演化过程中的涡旋结构。空化-涡流相互作用深刻地影响了空腔演化。一次弱涡和二次弱涡均对空腔脱落和U型结构的形成有显着影响。此外，兰姆矢量散度所描述的拉伸作用和涡度承载运动在深度上阐明了特殊空腔结构的形成。凭借平均速度、雷诺应力、Lumley 三角形和 Lumley 距离，还仔细研究了湍流特性。空化运动在扭曲水翼周围的湍流速度波动和湍流各向异性中起着重要作用。Lamb矢量散度所描述的拉伸作用和涡度承载运动在深度上阐明了特殊空腔结构的形成。凭借平均速度、雷诺应力、Lumley 三角形和 Lumley 距离，还仔细研究了湍流特性。空化运动在扭曲水翼周围的湍流速度波动和湍流各向异性中起着重要作用。Lamb矢量散度所描述的拉伸作用和涡度承载运动在深度上阐明了特殊空腔结构的形成。凭借平均速度、雷诺应力、Lumley 三角形和 Lumley 距离，还仔细研究了湍流特性。空化运动在扭曲水翼周围的湍流速度波动和湍流各向异性中起着重要作用。