Flow visualization experimental study on turbulent coherent structure in vegetated open channel flow

被引：0
|
作者：
Yan J. [1 ,2 ]
Dai K. [1 ,3 ]
Tang H. [1 ,2 ]
Chen Y. [1 ]
Zhang M. [1 ]
机构：
[1] College of Water Conservancy and Hydropower Eng., Hohai Univ., Nanjing
[2] State Key Lab. of Hydrology-Water Resources and Hydraulic Eng., Nanjing
[3] Guangdong Yuegang Water Supply Co. LTD, Shenzhen
来源：
Sichuan Daxue Xuebao (Gongcheng Kexue Ban)/Journal of Sichuan University (Engineering Science Edition) | 2016年 / 48卷 / 02期
关键词：
Burst phenomenon; Coherent structure; Flow visualization; Turbulence; Vegetated open channel flow; Vortex structure;
D O I：
10.15961/j.jsuese.2016.02.004
中图分类号：
学科分类号：
摘要：
The flow visualization technology and digital image processing theory were used to study the turbulent coherent structures in vegetated open channel flow. It was demonstrated that the plants in channel has changed the coherent structure which is totally different from that of open channel flows. According to the characteristics of the coherent structure, the flow was divided into three regions. In the vegetation inner region, the wake burst phenomenon and simil-Karman vortex streets coexist and the vortex structure is affected by the dimeter and the arrangement patten of the vegetation. In the region near the top of the vegetaion, the coherent structure is complicated and changes frequently. The bursting phenomenon in boundary and large eddy pairing phenomenon in freely mixing layer appear at the same time in this region, and the bursting period has negetative correlation with velocity, the mean penetration depth of vortex has positive correlation with velocity and submergence. The out region is similar to the free shear turbulence flow which appears in the outer layer of traditional open channel, having the structures of vortex stretching and turbulence intermittent. The coherent structures of the three regions are different from but interact on each other. © 2016, Editorial Department of Journal of Sichuan University (Engineering Science Edition). All right reserved.
引用
收藏
页码：21 / 27
页数：6
相关论文
共 16 条
  • [1] Tang H., Yan J., Lv S., Advances in research on flows with vegetation in river management, Advances in Water Science, 18, 5, pp. 785-792, (2007)
  • [2] Ghisalberti M., Nepf H.M., Mixing layers and coherent structures in vegetated aquatic flows, Journal of Geophysical Research, 107, C2, (2002)
  • [3] Ghisalberti M., Nepf H.M., The limited growth of vegetated shear layers, Water Resources Research, (2004)
  • [4] Nepf H.M., Ghisalberti M., Flow and transport in channels with submerged vegetation, Acta Geophysica, 56, 3, pp. 753-777, (2008)
  • [5] Poggi D., Porpotato A., Ridolfi L., The effect of vegetation density on canopy sub-layer turbulence, Boundary-Layer Meteorology, 111, 3, pp. 565-587, (2004)
  • [6] Yan J., Experimental study on flow resistance and turbulence characteristics of open channel flows with vegetation, (2008)
  • [7] Nezu I., Sanjou M., Turburence structure and coherent motion in vegetated canopy open channel flows, Journal of Hydro-environment Research, 2, 2, pp. 62-90, (2008)
  • [8] Poggi D., Katul G., Albertson J., Scalar dispersion within a model canopy: Measurements and three-dimensional large models, Advances in Water Resources, 29, 2, pp. 326-335, (2006)
  • [9] Zhang Y., The study on diffusion and dispersion characteristics of contaminants in flow with vegetation, (2012)
  • [10] Okamoto T., Nezu I., Ikeda H., Vertical mass and momentum transport in open-channel flows with submerged vegetations, Journal of Hydro-environment Rearch, 6, 4, pp. 287-297, (2012)
12