1991 Fiscal Year Final Research Report Summary
Evaluation of the disaster prevention function of channel works in mountainous river.
| Project/Area Number |
02452202
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| Research Category |
Grant-in-Aid for General Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Research Field |
Hydraulic engineering
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| Research Institution | Gifu University |
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Principal Investigator |
KOMURA Saburo Gifu Univ., Dept. of Civil Eng., Professor., 工学部, 教授 (40021571)
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| Co-Investigator(Kenkyū-buntansha) |
NAKATANI Tsuyoshi Gifu Univ., Dept. of Civil Eng., Asst., 工学部, 助手 (70155753)
FUJITA Ichiro Gifu Unvi., Dept. of Civil Eng., Associate Prof., 工学部, 助教授 (10127392)
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| Project Period (FY) |
1990 – 1991
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| Keywords | Mountainous River / Channel Works / Groundsill Works / Confluence / Hydraulic Jump / Shock Wave / Bed Variations / Finite Difference Method |
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| Research Abstract |
(1) Evaluation of the hydraulic characteristics and disaster prevention function of channel words
A numerical method was developed by means of Two-step Lax-Wendroff method and MacCormack method to compute a water-surface accompanying hydraulic jumps and shock waves. The MacCormack method was successfully applied to simulate the water-surface profiles in a channel with groundsill works. The hydraulic jump at the sudden change of slop was computed without a numerical occilation by the TVD MacCormack method. TVD-MacCormack scheme was expanded to the two-dimensional flow and it was able to calculate the flow at a confluence having subcritical and supercritical flows at the same time.
(2) Evaluation of the hydraulic characteristics and disaster prevention function at a confluence
Unsteady characteristics of a large scale vortex behavior downstream from the right-angled confluence was simulated by LES (large eddy simulation) model. In the case of steady state, it was found out that the size of the separation bubble was underestimated by a standard k-a model. Mean and turbulent flow fields and the size of a recirculating region were obtained by the image processing. The conditions for creation of hydraulic jump at the confluence was also studied by a physical model tests.
(3) Hydraulec characteristics on the sedimentation and disaster prevention function at the bend of the channel
A numerical method to compute the water-surface and river-bed variation downstream of groundsill works was presented by the TVD-MacCormack scheme. Experimental research was mainly placed on the hydraulic characteristics of the local scour in the downstream region of the consolidation dam installed at the bend part of the channel. The empical equation for estimating the maximum scour depth in the downstream of consolidation dam was developed for the straight channel. It was found out that the characteristics of local scour was affected by the shape of the levee crown of consolidation dam.
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