Research on LES for Flows with Generation of Turbulence at Small Scales

小尺度湍流产生流的 LES 研究

基本信息

批准号：
10650162
负责人：
HORIUTI Kiyosi
金额：
$ 2.05万
依托单位：
Tokyo Institute of Technology
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1998
资助国家：
日本
起止时间：
1998 至 1999
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-10650162/
关键词：
Vortex sheet and tube Direct numerial simulation Large-eddy simulation Homogeneous-isotropic turbulence Dissipation Energy transfer Subgrid-scale model Smagorinsky model Large-eddy simulation (LES)DNS Subgrid-scaleエネルギー Forward scat

项目摘要

The aim of the present study was to identify the structure which is most responsible for the transfer and dissipation of the turbulent energy, and conduct an assessment of the subgrid scale (SGS) models in large-eddy simulation (LES) on the accuracy for a prediction of energy transfer associated with these structures.We have developed a method to classify vortical structures into three categories, a flat sheet, a cylindrical sheet and a tube core. We generated direct numerical simulation (DNS) data of the homogeneous isotropic turbulence using 128ィイD13ィエD1 and 256ィイD13ィエD1 grid points for the cases with and without inputs of external energy at the large or small scales. It was shown using these databases that the proposed method yields an accurate classification of the data into three regions with the desired characteristics. By utilizing this method, we examined the contribution of these structures for the dissipation and cascade of turbulent energy in LES. It was shown that dissipati … More on and forward energy transfer primarily arises in the flat sheet region, whereas backward transfer primarily occurs in the compressed tube core region. In all of three regions, an intense generation of the azimuthal vorticity, placed perpendicular to the most stretched vorticity, was noticed.Then, we have conducted an assessment of the SGS models on its accuracy for prediction of the structures responsible for the transfer. The constant coefficient Smagorinsky model was an accurate model to represent the forward transfer. In the dynamic Smagorinsky model (DSM), the effect of the strain on the model was reduced, and an prediction accuracy for the structures responsible for energy transfer was significantly lowered.These SGS models were further assessed in actual LES. The Smagorinsky model yielded overestimate of forward transfer, and a poor prediction for an evolution of vortical structures. DSM yielded overestimate of contribution of the tube-core region, and a poor prediction of the dissipative structures. These drawbacks were circumvented in the SGS estimation model. Assessment of the results obtained in the present study at higher Reynolds numbers will be left to future work. Less

本研究的目的是确定最负责湍流能量转移和耗散的结构，并在大型模拟（LES）中评估亚网格量表（SGS）模型，以预测与这些结构相关的能量转移的准确性。我们已经开发了一种将涡流分为三个类别的方法。我们使用128 D13 D1和256 D13 D1网格点生成了均质的各向同性湍流的直接数值模拟（DNS）数据，用于在大或小尺度上具有外部能量输入的情况。使用这些数据库表明，所提出的方法将数据准确地分类为具有所需特征的三个区域。通过利用这种方法，我们检查了这些结构对LES中湍流能量耗散和级联的贡献。结果表明，在平板区域中，耗散的……更多关于正向能量转移的主要是出现的，而向后转移的主要发生在压缩管芯区域中。在三个区域中的所有区域中，都注意到了垂直于最伸展的涡度的强烈的方位角涡度。然后，我们对SGS模型进行了评估，以预测负责转移的结构的准确性。恒定核心Smagorinsky模型是代表正向传输的准确模型。在动态Smagorinsky模型（DSM）中，菌株对模型的影响减少了，并且负责能量转移的结构的预测准确性显着降低。在实际LE中进一步评估了这些SGS模型。 Smagorinsky模型对远期转移产生了高估，并且对涡旋结构的进化进行了较差的预测。 DSM对管核区域的贡献产生了高估，并且对耗散结构的预测差。这些缺点在SGS估计模型中得到了规避。对本研究在较高雷诺数中获得的结果的评估将留给将来的工作。较少的