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首页> 外文期刊>Physics of fluids >Turbulent structures of shock-wave diffraction over 90 degrees convex corner
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Turbulent structures of shock-wave diffraction over 90 degrees convex corner

机译：90度凸角超过90度的冲击波衍射湍流结构

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摘要

The turbulent structures and long-time flow dynamics of shock diffraction over 90 degrees convex corner associated with an incident shock Mach number M-s = 1.5 are investigated by large eddy simulation (LES). The average evolution of the core of the primary vortex is in agreement with the previous two dimensional studies. The Type-N wall shock structure is found to be in excellent agreement with the previous experimental data. The turbulent structures are well resolved and resemble those observed in the experimental findings. Subgrid scale dissipation and subgrid scale activity parameter are quantified to demonstrate the effectiveness of the LES. An analysis based on turbulent-nonturbulent interface reveals that locally incompressible regions exhibit the universal teardrop shape of the joint probability density function of the second and third invariants of the velocity gradient tensor. Stable focus stretching (SFS) structures dominate throughout the evolution in these regions. Stable node/saddle/saddle structures are found to be predominant at the early stage in locally compressed regions, and the flow structures evolve to more SFS structures at later stages. On the other hand, the locally expanded regions show a mostly unstable nature. From the turbulent kinetic energy, we found that the pressure dilatation remains important at the early stage, while turbulent diffusion becomes important at the later stage. Furthermore, the analysis of the resolved vorticity transport equation reveals that the stretching of vorticity due to compressibility and stretching of vorticity due to velocity gradients plays an important role compared to diffusion of vorticity due to viscosity as well as the baroclinic term. Published under license by AIP Publishing.
机译：通过大涡模拟（LES）研究了与入射冲击马赫数M-S = 1.5相关的冲击衍射的湍流结构和长时间流动动态。主要涡旋核心的平均演变与前两维研究一致。发现N型墙壁冲击结构与先前的实验数据相一致。湍流结构很好地解决并类似于实验结果中观察到的结构。量化尺度耗散和子级尺度活动参数被量化以证明LES的有效性。基于湍流 - 无湍流界面的分析揭示了局部不可压缩区域表现出速度梯度张量的第二和第三不变性的联合概率密度函数的通用泪珠形状。稳定的焦点拉伸（SFS）结构在这些地区的进化中占主导地位。发现稳定节点/鞍座/鞍座结构在局部压缩区域的早期阶段处于优势，并且流动结构在以后的阶段进化到更多SFS结构。另一方面，局部扩张的区域显示出最不稳定的性质。从动荡的动能来看，我们发现压力扩张在早期阶段仍然很重要，而湍流扩散在后期变得重要。此外，分辨的涡流传输方程的分析表明，由于速度梯度引起的压缩性和涡流的延伸引起的涡度的拉伸起到了与血管和曲金术语引起的涡度的扩散相比的重要作用。通过AIP发布在许可证下发布。

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  • 来源
    《Physics of fluids》 |2019年第8期|共15页
  • 作者

    Soni V.; Chaudhuri A.; Brahmi N.; Hadjadj A.;

  • 作者单位

    Normandie Univ INSA Rouen CNRS CORIA F-76000 Rouen France;

    OsloMet Oslo Metropolitan Univ Dept Civil Engn &

    Energy Technol Pilestredet 35 PB 4 St Olavs Plass N-0130 Oslo Norway;

    Normandie Univ INSA Rouen CNRS CORIA F-76000 Rouen France;

    Normandie Univ INSA Rouen CNRS CORIA F-76000 Rouen France;

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  • 正文语种 eng
  • 中图分类 流体力学;
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