1992 Fiscal Year Final Research Report Summary
Study on a mechanism of sheet-flow sediment transport
| Project/Area Number |
03650429
|
|---|
| Research Category |
Grant-in-Aid for General Scientific Research (C)
|
| Allocation Type | Single-year Grants |
|---|
| Research Field |
Hydraulic engineering
|
|---|
| Research Institution | Kagoshima University |
|---|
Principal Investigator |
ASANO Toshiyuki Kagoshima Univ., Dept. of Eng. Associate Professor, 工学部, 助教授 (40111918)
|
|---|
| Co-Investigator(Kenkyū-buntansha) |
NISHI Ryuichiro Kagoshima Univ., Dept. of Eng. Research Associate, 工学部, 助手 (30189253)
|
|---|
| Project Period (FY) |
1991 – 1992
|
| Keywords | Sheet-flow / Beach change / Sediment transport / Stormy wave / boundary layer Oscillatory / mixture Sediment-fluid / Saltation / Particle dynamics |
|---|
| Research Abstract |
Study on sheet-flow sediment transport has recently attracted much interest because severe beach erosions and shoalings of fairway occur under this mode. There have been many studies on sediment transport under low fluid tractive force. In comparison, the behavior of fluid/sediment mixture under high fluid tractive force is poorly understood. In this study, motions of sediment particles under oscillatory flows were measured with a high speed video camera, and the properties were carefully analyzed. The main results are as follows.
(1) The thickness of the sheet flow layer increases almost linearly with the Shields parameter. Meanwhile the thickness of the saltation layer does not increase with it noticeably.
(2) The profile of sediment concentration can be represented by an exponentially decay curve in the saltation layer, and an upward convex curve in the sheet-flow layer.
(3) The sediment transport rate was measured by the following two ways. One is estimated by the product of sediment concentration and sediment transport velocity, the other is to direct-trace a group of painted particles in the video frame. As a result, the two methods yield little difference in the obtained sediment transport rate. Little difference is also found between particle materials used as the sediment.
(4) The obtained sediment transport rates are plotted in the center of scatters reported by other researchers previously. The results also agree well with those predicted by Madsen-Grant formula.
(5) Although this investigation does not cover a very wide experimental range, the above obtained results yield useful information on the mechanics of the sheet-flow and quantitative description of the sediment transport.
|
