{"title":"近壁湍流中表皮摩擦力与对流速度之间的相关性","authors":"Tianshu Liu , Tao Chen , Massimo Miozzi","doi":"10.1016/j.euromechflu.2023.12.009","DOIUrl":null,"url":null,"abstract":"<div><p><span>The enstrophy convection velocity (denoted by </span><span><math><msub><mrow><mi>u</mi></mrow><mrow><mi>Ω</mi></mrow></msub></math></span><span>) in the evolution equation of the boundary enstrophy is proportional to skin friction (denoted by </span><span><math><mi>τ</mi></math></span><span>) in an incompressible viscous flow, which can be determined globally as an optical flow problem from a time sequence of the boundary enstrophy fields. The correlation coefficient between </span><span><math><mrow><mo>|</mo><mrow><msub><mrow><mi>u</mi></mrow><mrow><mi>Ω</mi></mrow></msub></mrow><mo>|</mo></mrow></math></span> and <span><math><mrow><mo>|</mo><mi>τ</mi><mo>|</mo></mrow></math></span><span> is evaluated in a turbulent channel flow at the friction Reynolds number </span><span><math><mrow><msub><mrow><mi>Re</mi></mrow><mrow><mi>τ</mi></mrow></msub><mo>=</mo><mn>180</mn></mrow></math></span><span>, which is about 0.73 in the region of interest containing near-wall strong wall-normal velocity event associated with a sweep-ejection pair) and is approximately independent of the wall-normal coordinate in the viscous sublayer. This correlation coefficient is contributed mainly by strong near-wall coherent structures with high boundary enstrophy. The statistics of the difference between the normalized </span><span><math><mrow><mo>|</mo><mrow><msub><mrow><mi>u</mi></mrow><mrow><mi>Ω</mi></mrow></msub></mrow><mo>|</mo></mrow></math></span> and <span><math><mrow><mo>|</mo><mi>τ</mi><mo>|</mo></mrow></math></span> are discussed. The statistical correlation between <span><math><msub><mrow><mi>u</mi></mrow><mrow><mi>Ω</mi></mrow></msub></math></span> and <span><math><mi>τ</mi></math></span> elucidates the connection between near-wall flow structures and skin friction.</p></div>","PeriodicalId":11985,"journal":{"name":"European Journal of Mechanics B-fluids","volume":null,"pages":null},"PeriodicalIF":2.5000,"publicationDate":"2023-12-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":"{\"title\":\"Correlation between skin friction and enstrophy convection velocity in near-wall turbulence\",\"authors\":\"Tianshu Liu , Tao Chen , Massimo Miozzi\",\"doi\":\"10.1016/j.euromechflu.2023.12.009\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"<div><p><span>The enstrophy convection velocity (denoted by </span><span><math><msub><mrow><mi>u</mi></mrow><mrow><mi>Ω</mi></mrow></msub></math></span><span>) in the evolution equation of the boundary enstrophy is proportional to skin friction (denoted by </span><span><math><mi>τ</mi></math></span><span>) in an incompressible viscous flow, which can be determined globally as an optical flow problem from a time sequence of the boundary enstrophy fields. The correlation coefficient between </span><span><math><mrow><mo>|</mo><mrow><msub><mrow><mi>u</mi></mrow><mrow><mi>Ω</mi></mrow></msub></mrow><mo>|</mo></mrow></math></span> and <span><math><mrow><mo>|</mo><mi>τ</mi><mo>|</mo></mrow></math></span><span> is evaluated in a turbulent channel flow at the friction Reynolds number </span><span><math><mrow><msub><mrow><mi>Re</mi></mrow><mrow><mi>τ</mi></mrow></msub><mo>=</mo><mn>180</mn></mrow></math></span><span>, which is about 0.73 in the region of interest containing near-wall strong wall-normal velocity event associated with a sweep-ejection pair) and is approximately independent of the wall-normal coordinate in the viscous sublayer. This correlation coefficient is contributed mainly by strong near-wall coherent structures with high boundary enstrophy. The statistics of the difference between the normalized </span><span><math><mrow><mo>|</mo><mrow><msub><mrow><mi>u</mi></mrow><mrow><mi>Ω</mi></mrow></msub></mrow><mo>|</mo></mrow></math></span> and <span><math><mrow><mo>|</mo><mi>τ</mi><mo>|</mo></mrow></math></span> are discussed. The statistical correlation between <span><math><msub><mrow><mi>u</mi></mrow><mrow><mi>Ω</mi></mrow></msub></math></span> and <span><math><mi>τ</mi></math></span> elucidates the connection between near-wall flow structures and skin friction.</p></div>\",\"PeriodicalId\":11985,\"journal\":{\"name\":\"European Journal of Mechanics B-fluids\",\"volume\":null,\"pages\":null},\"PeriodicalIF\":2.5000,\"publicationDate\":\"2023-12-23\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"\",\"citationCount\":\"0\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"European Journal of Mechanics B-fluids\",\"FirstCategoryId\":\"5\",\"ListUrlMain\":\"https://www.sciencedirect.com/science/article/pii/S0997754623001826\",\"RegionNum\":3,\"RegionCategory\":\"工程技术\",\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"Q2\",\"JCRName\":\"MECHANICS\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"European Journal of Mechanics B-fluids","FirstCategoryId":"5","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S0997754623001826","RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q2","JCRName":"MECHANICS","Score":null,"Total":0}
Correlation between skin friction and enstrophy convection velocity in near-wall turbulence
The enstrophy convection velocity (denoted by ) in the evolution equation of the boundary enstrophy is proportional to skin friction (denoted by ) in an incompressible viscous flow, which can be determined globally as an optical flow problem from a time sequence of the boundary enstrophy fields. The correlation coefficient between and is evaluated in a turbulent channel flow at the friction Reynolds number , which is about 0.73 in the region of interest containing near-wall strong wall-normal velocity event associated with a sweep-ejection pair) and is approximately independent of the wall-normal coordinate in the viscous sublayer. This correlation coefficient is contributed mainly by strong near-wall coherent structures with high boundary enstrophy. The statistics of the difference between the normalized and are discussed. The statistical correlation between and elucidates the connection between near-wall flow structures and skin friction.
期刊介绍:
The European Journal of Mechanics - B/Fluids publishes papers in all fields of fluid mechanics. Although investigations in well-established areas are within the scope of the journal, recent developments and innovative ideas are particularly welcome. Theoretical, computational and experimental papers are equally welcome. Mathematical methods, be they deterministic or stochastic, analytical or numerical, will be accepted provided they serve to clarify some identifiable problems in fluid mechanics, and provided the significance of results is explained. Similarly, experimental papers must add physical insight in to the understanding of fluid mechanics.