2004 Fiscal Year Final Research Report Summary
Study on behavior wind-induced flow and water quality in a density stratified closed water area with aquatic plants
| Project/Area Number |
14360145
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Irrigation, drainage and rural engineering/Rural planning
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| Research Institution | KYUSHU UNIVERSITY |
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Principal Investigator |
MORI Ken KYUSHU UNIVERSITY, Faculty of Agriculture, Professor, 大学院・農学研究院, 教授 (50117272)
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| Co-Investigator(Kenkyū-buntansha) |
SHIKASHO Shiomi KYUSHU UNIVERSITY, Faculty of Agriculture, Professor, 大学院・農学研究院, 教授 (80038265)
NAKANO Yosisuke KYUSHU UNIVERSITY, Faculty of Agriculture, Professor, 大学院・農学研究院, 教授 (60038320)
INOUE Eiji KYUSHU UNIVERSITY, Faculty of Agriculture, Associate Professor, 大学院・農学研究院, 助教授 (00184739)
HIRAMATSU Kazuaki KYUSHU UNIVERSITY, Faculty of Agriculture, Associate Professor, 大学院・農学研究院, 助教授 (10199094)
HARAGUCHI Tomokazu KYUSHU UNIVERSITY, Faculty of Agriculture, Research Associate, 大学院・農学研究院, 助手 (90346833)
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| Project Period (FY) |
2002 – 2004
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| Keywords | closed water area / aquatic plant / density stratified flow / wind induced flow / entrainment phenomenon / turbulent structure / water quality / dissolved oxygen |
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| Research Abstract |
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.
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