1987 Fiscal Year Final Research Report Summary
Study on Unequilibrium Sediment Transport Rate and Local Scour around Structures
| Project/Area Number |
61550365
|
|---|
| Research Category |
Grant-in-Aid for General Scientific Research (C)
|
| Allocation Type | Single-year Grants |
|---|
| Research Field |
Hydraulic engineering
|
|---|
| Research Institution | TOHOKU UNIVERSITY |
|---|
Principal Investigator |
SAWAMOTO Masaki Tohoku University, Professor, 工学部, 教授 (90016519)
|
|---|
| Co-Investigator(Kenkyū-buntansha) |
NISHIZAWA Masaru Tohoku University, Research Associate, 工学部, 助手 (00005505)
|
|---|
| Project Period (FY) |
1986 – 1987
|
| Keywords | Local scour / Cylinder / Wave / Sand Drift |
|---|
| Research Abstract |
Following three items were studied.
1) Dynamic roll of nonequilibrium of sediment transport on bottom topography change under the wave action: The stability of sand bed was analysed theoretically. It was confirmed that the nonequilibrium of sand transport and scattering of step length are necessary for existance of single dominant length of bottom topograpy although asymmetry of sand transport rate make the bed unstable. The results were reported in the first reference.
2) Sediment transport rate in sheet flow regime: A series of experiment on sediment transport phenomena were carried out in sheet flow regime using an U-shape tube. Sediment transport rate, sediment motion and velocity distributions were measured. The 1.5 power relationship between transport rate and the bed shear stress was concluded. The limit of sheet flow regim was also discussed. The results were reported in the second reference.
3) Local scour around a cylinder under the wave action: A series of experiments were performed in a wave tank. The observed shapes of scour were classified into two category. The mechanism of scour was discussed considering the interaction of the flow and the bed. The roll of shedded vortices was confirmed through the flow visualization technique.
|
