基于诊断函数的薄层流对数律研究  

Logarithmic law of shallow water flow by using diagnostic function

作　　者：杨坪坪 张玉珊 李瑞 张会兰[3,4] 王云琦[3,4] Yang Pingping;Zhang Yushan;Li Rui;Zhang Huilan;Wang Yunqi(School of Karst Science,Guizhou Normal University,Guiyang 550001,China;State Engineering Technology Institute for Karst Desertification Control,Guiyang 550001,China;Three-Gorges Area(Chongqing)Forest Ecosystem Research Station of Ministry of Education,School of Soil and Water Conservation,Beijing Forestry University,Beijing 100083,China;Chongqing Jinyun Forest Eco-System Research Station,School of Soil and Water Conservation,Beijing Forestry University,Beijing 100083,China)

机构地区：[1]贵州师范大学喀斯特研究院,贵阳550001 [2]国家喀斯特石漠化防治工程技术研究中心,贵阳550001 [3]北京林业大学水土保持学院重庆三峡库区森林生态系统教育部野外科学观测研究站,北京100083 [4]北京林业大学水土保持学院重庆缙云山三峡库区森林生态系统国家定位观测研究站,北京100083

出　　处：《农业工程学报》2021年第1期167-175,共9页Transactions of the Chinese Society of Agricultural Engineering

基　　金：国家自然科学基金(32060372);贵州省教育厅青年科技人才成长项目(黔教合KY字[2021]293);贵州师范大学2019年博士科研启动项目(GZNUD[2019]3号)。

摘　　要：薄层流是一种特殊形态的明渠流,其特点是水深浅薄。为探讨薄层流流速分布是否满足对数律,该研究利用高分辨率粒子图像测速(Particle Image Velocimetry,PIV)技术,分析8组薄层流(水深0.49~1.1 cm,雷诺数835~2877)及1组深水明渠紊流(对照)床面至水面的流速分布、紊动强度及雷诺应力。并基于诊断函数,研究薄层流流速是否满足对数律、对数区的范围及卡门常数变化规律。结果表明,薄层流的无量纲流速从过渡区开始偏离深水明渠水流中的理论曲线;薄层流的流向紊动强度大于深水明渠紊流,但垂向紊动强度小于深水明渠紊流,随着水深的增加,两者的紊动强度逐渐重合;雷诺应力的特征表明,随着水深的增加,受黏性力影响的范围越来越小。薄层流诊断函数曲线的特征说明薄层流中不存在严格意义的对数区,但当水深极浅时(水深≤0.53 cm),流速基本满足对数律,且卡门常数在0.2~0.3范围内。当水深和雷诺数增加,薄层流诊断函数曲线出现波动而不再近似水平。为方便实际计算,若允许诊断函数有一定的倾斜,对数区在极大值与极小值之间的范围,薄层流的卡门常数随着雷诺数的增加而增加。此外,薄层流对数区的范围并非稳定,随着雷诺数的增加,对数区影响的范围变大。该研究可为薄层流的理论研究和流速计算提供参考。Shallow water flow is a special type of open channel flow,where the fluid behaves with a free surface in a canal.The flow depth of shallow water flow is extremely thin,and even reaches several millimeters.At present,there is no obvious evidence that the logarithmic theory is suitable for shallow water flow,even though it is widely used to describe velocity profile for open channel flow.The reason is that the viscous and inertia force exert no significant influences on shallow water flow,due to extremely thin flow depth.It is necessary to clarify the presence of the region without influenced by viscous and inertia force.The present study aims to analyze the velocity characteristics of shallow water flow,thereby to verify logarithmic law using diagnostic function.The Particle Image Velocimetry(PIV)with high resolution(64 pixels/mm)was also used to measure flow fields.Eight conditions of shallow water flow were surveyed(flow depth ranged from 0.49 to 1.1 cm and Reynolds number ranged from 835 to 2877),and a deep-water open channel flow was considered as control group.The statistical parameters were measured,including the velocity distribution from flume bed to free surface,streamwise and wall-normal turbulent intensity.Logarithmic theory was also explored,such as the diagnostic function,Karman constant,and scope of log-law region.Results showed that:1)From the transition region,dimensionless streamwise velocity of shallow water flow deviated from the logarithmic law,which was used in deep-water open channel flow.The streamwise turbulent intensity of shallow water flow was larger than that of deep-water open channel turbulent flow,while the wall-normal turbulent intensity was smaller than that.The turbulent intensity of two flows gradually overlapped with increasing flow depth.The characteristics of Reynolds stress showed that the region influenced by viscous force became smaller as the flow depth increased.2)There weren’t strict horizontal lines in the diagnostic function curves,implying that there was no strict l

关 键 词：流速 粒子图像测速 渠道 薄层流 卡门常数 诊断函数 对数律 

分 类 号：TV131.3[水利工程—水力学及河流动力学] TV732.6