苦草对水流结构的影响研究  

Impact of Vallisneria natans on flow structure

作　　者：张英豪[1,2] 赖锡军[1] 

机构地区：[1]中国科学院南京地理与湖泊研究所流域地理学重点实验室,江苏南京210008 [2]中国科学院大学,北京100049

出　　处：《水科学进展》2015年第1期99-106,共8页Advances in Water Science

基　　金：国家重点基础研究发展计划(973计划)资助项目(2012CB417000);国家自然科学基金资助项目(41071021)~~

摘　　要：为研究沉水植被对水流结构的影响,以苦草为对象,利用实验室水槽实验研究了含淹没水生植被水流时均流速、雷诺应力及紊动能的垂向分布特征。受苦草冠层的影响,时均流速在冠顶以上呈对数分布,且随着流量的增加,冠层倾伏高度降低,对数剖面愈加明显;冠层内部,由于冠层阻流面积在垂向分布上的差异,冠层内时均流速出现逆梯度分布,且在床面附近出现局部流速最大值。雷诺应力在冠顶附近达到最大值,并向水面与床底方向逐渐减小;受逆流速梯度的影响,冠层内部雷诺应力出现负值以及局部最大值。雷诺应力产生的剪切紊动使得紊动能在冠顶处最大,并向水面与床底进行垂向传输;受紊动传输距离的限制,冠层底部以叶片后产生的尾流紊动为主,紊动能较小。In order to study the impact of submerged vegetation on flow structure,flume experiments were conducted to measure the mean velocity,the Reynolds stress and the turbulence kinetic energy of flow with Vallisneria natans canopy. Influenced by Vallisneria natans canopy,a logarithmic profile is generally presented above the canopy. As a difference exists in the vertical distribution of frontal area,a region with counter velocity gradient and a local velocity maximum appear inside the canopy. The Reynolds stress reaches maximum around the top of canopy and decreases gradually in both upward and downward. Due to the existence of counter velocity gradient,negative stress and a local stress maximum are produced within the canopy. Turbulence produced by shear stress makes turbulence kinetic energy reach maximum around the top of canopy and transmits vertically towards the bed. Restricted by the limited distance of the vertical transportation of turbulence,wake production becomes the major source of turbulence,and the turbulence kinetic energy diminishes dramatically at the bottom of canopy.

关 键 词：水生植被 时均流速 雷诺应力 紊动能 

分 类 号：TV143[水利工程—水力学及河流动力学]