陡度对正弦粗糙表面上湍流传热的影响

IF 2.6 3区 工程技术 Q2 ENGINEERING, MECHANICAL
Y. Kuwata, W. Yagasaki, K. Suga
{"title":"陡度对正弦粗糙表面上湍流传热的影响","authors":"Y. Kuwata,&nbsp;W. Yagasaki,&nbsp;K. Suga","doi":"10.1016/j.ijheatfluidflow.2024.109537","DOIUrl":null,"url":null,"abstract":"<div><p>We conducted a direct numerical simulation (DNS) study to investigate the impact of surface undulation steepness on rough wall turbulent heat transfer. The flow geometry was turbulent open-channel flow over three-dimensional sinusoidal rough surfaces. To examine the effects of steepness, we systematically varied the streamwise and spanwise wavelengths of the sinusoidal roughness while keeping the roughness height constant. The friction Reynolds number ranged from 180 to 600, and we considered a passive scalar with the fluid Prandtl number was 0.7, assuming air flow conditions. In the fully rough regime, the velocity roughness function is expressed as a function of the inner-scaled equivalent sand grain roughness <span><math><msubsup><mrow><mi>k</mi></mrow><mrow><mi>s</mi></mrow><mrow><mo>+</mo></mrow></msubsup></math></span> independent of steepness, whereas the steeper surfaces with shorter wavelengths result in larger temperature roughness functions at the same <span><math><msubsup><mrow><mi>k</mi></mrow><mrow><mi>s</mi></mrow><mrow><mo>+</mo></mrow></msubsup></math></span> value. Analysis of the physical mechanisms that increases the roughness function shows that the pressure drag primarily contributes to the increase in the velocity roughness function, while the temperature roughness function is mainly augmented by the roughness-induced wall heat transfer term, correlating with the steepness of the surface undulations. It is also suggested that the effective slope, which quantifies the steepness of rough surfaces, could improve the predictive accuracy of existing correlations for the temperature roughness function.</p></div>","PeriodicalId":335,"journal":{"name":"International Journal of Heat and Fluid Flow","volume":"109 ","pages":"Article 109537"},"PeriodicalIF":2.6000,"publicationDate":"2024-08-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":"{\"title\":\"Effects of steepness on turbulent heat transfer over sinusoidal rough surfaces\",\"authors\":\"Y. Kuwata,&nbsp;W. Yagasaki,&nbsp;K. Suga\",\"doi\":\"10.1016/j.ijheatfluidflow.2024.109537\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"<div><p>We conducted a direct numerical simulation (DNS) study to investigate the impact of surface undulation steepness on rough wall turbulent heat transfer. The flow geometry was turbulent open-channel flow over three-dimensional sinusoidal rough surfaces. To examine the effects of steepness, we systematically varied the streamwise and spanwise wavelengths of the sinusoidal roughness while keeping the roughness height constant. The friction Reynolds number ranged from 180 to 600, and we considered a passive scalar with the fluid Prandtl number was 0.7, assuming air flow conditions. In the fully rough regime, the velocity roughness function is expressed as a function of the inner-scaled equivalent sand grain roughness <span><math><msubsup><mrow><mi>k</mi></mrow><mrow><mi>s</mi></mrow><mrow><mo>+</mo></mrow></msubsup></math></span> independent of steepness, whereas the steeper surfaces with shorter wavelengths result in larger temperature roughness functions at the same <span><math><msubsup><mrow><mi>k</mi></mrow><mrow><mi>s</mi></mrow><mrow><mo>+</mo></mrow></msubsup></math></span> value. Analysis of the physical mechanisms that increases the roughness function shows that the pressure drag primarily contributes to the increase in the velocity roughness function, while the temperature roughness function is mainly augmented by the roughness-induced wall heat transfer term, correlating with the steepness of the surface undulations. It is also suggested that the effective slope, which quantifies the steepness of rough surfaces, could improve the predictive accuracy of existing correlations for the temperature roughness function.</p></div>\",\"PeriodicalId\":335,\"journal\":{\"name\":\"International Journal of Heat and Fluid Flow\",\"volume\":\"109 \",\"pages\":\"Article 109537\"},\"PeriodicalIF\":2.6000,\"publicationDate\":\"2024-08-26\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"\",\"citationCount\":\"0\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"International Journal of Heat and Fluid Flow\",\"FirstCategoryId\":\"5\",\"ListUrlMain\":\"https://www.sciencedirect.com/science/article/pii/S0142727X24002625\",\"RegionNum\":3,\"RegionCategory\":\"工程技术\",\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"Q2\",\"JCRName\":\"ENGINEERING, MECHANICAL\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"International Journal of Heat and Fluid Flow","FirstCategoryId":"5","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S0142727X24002625","RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q2","JCRName":"ENGINEERING, MECHANICAL","Score":null,"Total":0}
引用次数: 0

摘要

我们进行了一项直接数值模拟(DNS)研究,以探讨表面起伏陡度对粗糙壁面湍流传热的影响。流动的几何形状是三维正弦粗糙表面上的湍流明渠流动。为了研究陡度的影响,我们在保持粗糙度高度不变的情况下,系统地改变了正弦粗糙度的流向和跨向波长。摩擦雷诺数从 180 到 600 不等,假定气流条件下,我们考虑了流体普朗特数为 0.7 的被动标量。在完全粗糙状态下,速度粗糙度函数表示为内标度等效沙粒粗糙度 ks+ 的函数,与陡度无关,而在相同 ks+ 值下,波长较短的陡峭表面会导致较大的温度粗糙度函数。对粗糙度函数增加的物理机制的分析表明,压力阻力主要导致速度粗糙度函数的增加,而温度粗糙度函数主要由粗糙度引起的壁面传热项增加,这与表面起伏的陡度有关。研究还提出,量化粗糙表面陡度的有效斜率可以提高现有温度粗糙度函数相关性的预测精度。
本文章由计算机程序翻译,如有差异,请以英文原文为准。
Effects of steepness on turbulent heat transfer over sinusoidal rough surfaces

We conducted a direct numerical simulation (DNS) study to investigate the impact of surface undulation steepness on rough wall turbulent heat transfer. The flow geometry was turbulent open-channel flow over three-dimensional sinusoidal rough surfaces. To examine the effects of steepness, we systematically varied the streamwise and spanwise wavelengths of the sinusoidal roughness while keeping the roughness height constant. The friction Reynolds number ranged from 180 to 600, and we considered a passive scalar with the fluid Prandtl number was 0.7, assuming air flow conditions. In the fully rough regime, the velocity roughness function is expressed as a function of the inner-scaled equivalent sand grain roughness ks+ independent of steepness, whereas the steeper surfaces with shorter wavelengths result in larger temperature roughness functions at the same ks+ value. Analysis of the physical mechanisms that increases the roughness function shows that the pressure drag primarily contributes to the increase in the velocity roughness function, while the temperature roughness function is mainly augmented by the roughness-induced wall heat transfer term, correlating with the steepness of the surface undulations. It is also suggested that the effective slope, which quantifies the steepness of rough surfaces, could improve the predictive accuracy of existing correlations for the temperature roughness function.

求助全文
通过发布文献求助,成功后即可免费获取论文全文。 去求助
来源期刊
International Journal of Heat and Fluid Flow
International Journal of Heat and Fluid Flow 工程技术-工程:机械
CiteScore
5.00
自引率
7.70%
发文量
131
审稿时长
33 days
期刊介绍: The International Journal of Heat and Fluid Flow welcomes high-quality original contributions on experimental, computational, and physical aspects of convective heat transfer and fluid dynamics relevant to engineering or the environment, including multiphase and microscale flows. Papers reporting the application of these disciplines to design and development, with emphasis on new technological fields, are also welcomed. Some of these new fields include microscale electronic and mechanical systems; medical and biological systems; and thermal and flow control in both the internal and external environment.
×
引用
GB/T 7714-2015
复制
MLA
复制
APA
复制
导出至
BibTeX EndNote RefMan NoteFirst NoteExpress
×
提示
您的信息不完整,为了账户安全,请先补充。
现在去补充
×
提示
您因"违规操作"
具体请查看互助需知
我知道了
×
提示
确定
请完成安全验证×
copy
已复制链接
快去分享给好友吧!
我知道了
右上角分享
点击右上角分享
0
联系我们:info@booksci.cn Book学术提供免费学术资源搜索服务,方便国内外学者检索中英文文献。致力于提供最便捷和优质的服务体验。 Copyright © 2023 布克学术 All rights reserved.
京ICP备2023020795号-1
ghs 京公网安备 11010802042870号
Book学术文献互助
Book学术文献互助群
群 号:481959085
Book学术官方微信