Effects of mean shear on the vortex identification and the orientation statistics

IF 3.2 3区工程技术 Q2 MECHANICS

Theoretical and Applied Mechanics Letters Pub Date : 2023-07-01 DOI:10.1016/j.taml.2023.100454

Tianyi Bai , Cheng Cheng , Lin Fu

{"title":"Effects of mean shear on the vortex identification and the orientation statistics","authors":"Tianyi Bai , Cheng Cheng , Lin Fu","doi":"10.1016/j.taml.2023.100454","DOIUrl":null,"url":null,"abstract":"<div><p>This work compares the threshold applied to the swirling strength as well as the vortex orientation statistics in the total and fluctuating velocity fields using direct numerical simulations of compressible and incompressible turbulent channel flows. It is concluded that the difference in the swirling strength for vortex identification is minimal in the logarithmic region such that these two situations share the same threshold. Regarding the vortex orientation, the inclination angle remains similar. However, as the wall-normal distance increases, a more and more obvious distinction is noticed for its orientation with respect to the spanwise (<span><math><mi>z</mi></math></span>) direction. It is mainly due to their intrinsic differences and attendant contrasting preference for the vortex identification, i.e., vortices rotating in the <span><math><mrow><mo>−</mo><mi>z</mi></mrow></math></span> direction for the total velocity field and in the <span><math><mi>z</mi></math></span> direction for the fluctuating one. These observations function as a reasonable explanation for various remarks in previous studies.</p></div>","PeriodicalId":46902,"journal":{"name":"Theoretical and Applied Mechanics Letters","volume":null,"pages":null},"PeriodicalIF":3.2000,"publicationDate":"2023-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"1","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Theoretical and Applied Mechanics Letters","FirstCategoryId":"5","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S2095034923000259","RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q2","JCRName":"MECHANICS","Score":null,"Total":0}

引用次数: 1

Abstract

This work compares the threshold applied to the swirling strength as well as the vortex orientation statistics in the total and fluctuating velocity fields using direct numerical simulations of compressible and incompressible turbulent channel flows. It is concluded that the difference in the swirling strength for vortex identification is minimal in the logarithmic region such that these two situations share the same threshold. Regarding the vortex orientation, the inclination angle remains similar. However, as the wall-normal distance increases, a more and more obvious distinction is noticed for its orientation with respect to the spanwise ( $z$ ) direction. It is mainly due to their intrinsic differences and attendant contrasting preference for the vortex identification, i.e., vortices rotating in the $- z$ direction for the total velocity field and in the $z$ direction for the fluctuating one. These observations function as a reasonable explanation for various remarks in previous studies.

查看原文本刊更多论文

平均切变对涡旋识别和方向统计的影响

本文通过对可压缩和不可压缩湍流通道流动的直接数值模拟，比较了总速度场和脉动速度场中用于旋涡强度的阈值以及旋涡方向统计。结果表明，在对数区域内，涡识别的旋流强度差异极小，两种情况具有相同的阈值。在旋涡方向上，倾斜角保持不变。然而，随着墙法向距离的增加，其方向相对于展向(z)方向的区别越来越明显。这主要是由于它们在涡旋识别上的内在差异和相应的偏好对比，即总速度场的涡旋方向为−z，脉动速度场的涡旋方向为z。这些观察结果可以合理地解释以往研究中的各种评论。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

求助全文

约1分钟内获得全文求助全文

来源期刊

Theoretical and Applied Mechanics Letters MECHANICS-

CiteScore

6.20

自引率

2.90%

发文量

545

审稿时长

12 weeks

期刊介绍： An international journal devoted to rapid communications on novel and original research in the field of mechanics. TAML aims at publishing novel, cutting edge researches in theoretical, computational, and experimental mechanics. The journal provides fast publication of letter-sized articles and invited reviews within 3 months. We emphasize highlighting advances in science, engineering, and technology with originality and rapidity. Contributions include, but are not limited to, a variety of topics such as: • Aerospace and Aeronautical Engineering • Coastal and Ocean Engineering • Environment and Energy Engineering • Material and Structure Engineering • Biomedical Engineering • Mechanical and Transportation Engineering • Civil and Hydraulic Engineering Theoretical and Applied Mechanics Letters (TAML) was launched in 2011 and sponsored by Institute of Mechanics, Chinese Academy of Sciences (IMCAS) and The Chinese Society of Theoretical and Applied Mechanics (CSTAM). It is the official publication the Beijing International Center for Theoretical and Applied Mechanics (BICTAM).