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Study on behavior wind-induced flow and water quality in a density stratified closed water area with aquatic plants

水生植物密度分层封闭水域风生流及水质研究

基本信息

批准号：
14360145
负责人：
MORI Ken
金额：
$ 7.3万
依托单位：
KYUSHU UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2002
资助国家：
日本
起止时间：
2002 至 2004
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-14360145/
关键词：
closed water area aquatic plant density stratified flow wind induced flow entrainment phenomenon turbulent structure water quality dissolved oxygen 浮葉性植物密度2成層溶存酸素日サイクル変動

项目摘要

Water environmental dynamics in closed water areas with density stratify such as ponds, reservoirs, lakes and estuaries are effected by turbulent flows based on mechanical and thermal disturbances. The thermal disturbance consists of lighting and heating based on solar radiation in the daytime and cooling based on emission at the night. The mechanical disturbance of wind induced flow and wind wave generated by wind action on the surface. We considered the mechanical disturbance of wind induced flow was generated by wind action on the surface in the closed water areas. An experimental investigation of turbulent entrainment induced by the mechanical disturbance was carried out in a laboratory wind -wave tank. We considered that the occupying rate of the floating water plants to the water surface affected on the turbulent entrainment in the closed water area. The results indicated that the existence the floating water plants contributed to make a significant effect on the scale of the turbulent entrainment. It was also found that the entrainment velocity depended on the Richardson number to the power of-3/2, the stability parameter of density stratified fluid flow. The following conclusions can be drawn : (1).From the experiment of entrainment velocity, the increase of the covered rate β of floating water plants decreases the entrainment velocity of the upper layer. (2).From the experiment of turbulent structure, the increase of the covered rate of floating water plants decreases the amount of turbulent energy. (3).The increase of the covered rate β of floating water plants decreases the turbulent energy of the upper layer that is produced at the surface. As the turbulent energy is transformed into potential energy, a close relationship between the decrease of entrainment velocity and the turbulent structure is clearly established.

在具有密度分层的封闭水域，如池塘、水库、湖泊和河口，水环境动力学受到基于机械和热力扰动的湍流的影响。热扰动包括白天基于太阳辐射的照明和加热以及夜间基于排放的冷却。风作用于地面产生的风致流和风浪的机械扰动。本文认为，在封闭水域中，风致流的机械扰动是由风对水面的作用产生的。在实验室风浪池中对机械扰动引起的湍流卷吸进行了实验研究。认为浮式水生植物对水面的占有率对封闭水域的紊动卷吸有影响。结果表明，浮游植物的存在对紊动卷吸尺度有显著影响。卷吸速度与密度分层流动的稳定性参数Richardson数的-3/2次方有关。得出以下结论：（1）.从卷吸速度实验来看，随着浮式水草覆盖率β的增大，上层卷吸速度减小。（2）从湍流结构的实验来看，随着浮式水草覆盖率的增加，湍流能量的大小减小。（3）浮式水生植物覆盖率β的增大，使在水面产生的上层湍流能量减小。由于湍流能量转化为位能，卷吸速度的减小与湍流结构之间存在着密切的关系。