Papers by Terunori Ohmoto
Vulnerability, Risk and Complexity: Impacts of global Change on Human Habitats (IAPS 21 Conference, Abstracts of Presentations), 2010
Proceedings of the International Conference on Civil, Structural and Transportation Engineering, Jun 1, 2022
In the Shirakawa River, remarkable deformation due to sediment deposition was observed after rive... more In the Shirakawa River, remarkable deformation due to sediment deposition was observed after river channel improvement works. In this research, a model experiment and a quasi-three-dimensional numerical simulation were conducted in order to evaluate the effect of river bend curvature variation caused by improvement works on channel response and flow capacity. In the model experiment, large sandbars were formed, and the channel became narrower. In the numerical simulation, flood flew over sandbars and gravel deposited on sandbars, which caused decreasing of flow capacity. The gravel deposition was most active when the flow charge was in its peak.
Doboku gakkai ronbunshu, 2021
Doboku gakkai ronbunshu, 2021
Doboku gakkai ronbunshu, 2019
8th IAHR World Congress - "Water: Connecting the World", Sep 1, 2019
The cavity zone along riverside is expected to produce native habitats of various ecosystems and ... more The cavity zone along riverside is expected to produce native habitats of various ecosystems and water-friendly environment. However, there is also a problem such as concern about deterioration of water quality because of a dead watet area. In this research, we have clarified the flow structure when the cavity aspect ratio changes for a flow field in which side cavity are continuously arranged in the downward flow direction. The flow velocity were measured by using PIV. As a result, it was clarified that the influence of the side cavity extended around the sidewall on the opposite bank side because of the flowing direction length of the cavity long in this experiment case. Furthermore, we also clarified how the turbulence generation term and the direct heat dissipa-tion term change in the turbulent energy balance formula when changing the aspect ratio of the side cavity.
International Journal of Environmental Protection and Policy, 2018
The flood behavior often affected by bridges, due to the accumulation of debris around bridge pie... more The flood behavior often affected by bridges, due to the accumulation of debris around bridge piers or the reduction of flow late. On the other hand, the effect of a bridge on a flood was not well studied. In this research, the simulation of the flood in the Kagetsu River in July, 2017 was conducted using 2D flow model in order to evaluate the effect of a bridge on the flood capacity, water level and flood scale. The flood behavior in residential area was also simulated. As a result, the bridge increased inundation velocity and inundation area, especially in the area around the bridge. When water level exceeds the height of bridge, flow discharge was limited by the area of bridge opening, which caused flow capacity decreasing. The stream force of flood was relatively strong at the area around the bridge.
Proceedings of the 34th World Congress of the International Association for Hydro- Environment Research and Engineering: 33rd Hydrology and Water Resources Symposium and 10th Conference on Hydraulics in Water Engineering, 2011
The necessity to understand and predict flows that carry large suspended sediment and wash loads ... more The necessity to understand and predict flows that carry large suspended sediment and wash loads has become acute in the Yellow River Basin where significant erosion and siltation associated with hyperconcentrated flood give rise to many river problems. Mud flows, debris flows or slurries, made up of a large amount of clay and/or silt particles suspended in water, often show non- Newtonian properties but remain poorly understood concerning the impacts of their rheological properties on fully developed turbulent structure. In this paper, we experimentally investigated the effects of non-Newtonian fluid on the separation vortex over fixed dune type bed by using Particle Image Velocimetry(PIV). The results showed that rheological properties significantly dissipated the turbulent flow fluctuations over the dune bed and augmented the flow resistance by comparison with the clear water flow.
AGU Fall Meeting Abstracts, Dec 1, 2020
AGU Fall Meeting Abstracts, Dec 1, 2020
Proceedings of the 34th World Congress of the International Association for Hydro- Environment Research and Engineering: 33rd Hydrology and Water Resources Symposium and 10th Conference on Hydraulics in Water Engineering, 2011
CRC Press eBooks, Aug 12, 2014
Understanding of hydraulic mechanism on and around the side weir is essential for the facilities ... more Understanding of hydraulic mechanism on and around the side weir is essential for the facilities to be designed and to be maintained well. Although past studies have advanced our ability to estimate the overflow discharge from side weir, detailed study of the tree-dimensional turbulent structure in an open channel flow with overflow from a side weir has been lacking. Authors have carried out an experimental study of the three-dimensional flow structure in an open channel flow of an aspect ratio two with overflow from a side weir. In this study, we carried out similar study on the case of open channel flow with an aspect ratio of three. The study found some differences in secondary flow characteristics between the aspect ratio two and the aspect ratio three.
Ōyō rikigaku rombunshū, 2002
Spur dikes have been used to realign a channel or redirect main flow away from a streambank to pr... more Spur dikes have been used to realign a channel or redirect main flow away from a streambank to protect it from erosive tractive forces. They are also used to increase channel roughness at locations that lack roughness elements. In certain cases, spur dikes can be used to narrow the channel in low-gradient, aggrading reaches causing flow velocities and sediment transport rates to increase. Water surface oscillation was produced in dikes fields when non-submerged spur dikes were set up in a case of their arrangements. The water surface oscillation was attributed to the interaction of large scale eddies formed in the spur dike fields along both banks, and was probably triggered by the separation eddies behind the first spur dike. This study focused on the interaction between water surface oscillation and large eddies in both cases of spur dike set up along both banks and one bank. The result showed that when a remarkable water surface oscillation was observed, the interaction of the large eddies in both banks was strong.
Doboku gakkai ronbunshu, 2022
Doboku gakkai ronbunshu, 2022
Proceedings of the 39th IAHR World Congress, 2022
Doboku gakkai ronbunshu, 2021
The necessity to understand and predict flows that carry large suspended sediment and wash loads ... more The necessity to understand and predict flows that carry large suspended sediment and wash loads has become acute in the Shirakawa River Basin where significant erosion and siltation associated with hyperconcentrated flood give rise to many river problems. Mud flows, debris flows or slurries, made up of a large amount of clay and/or silt particles suspended in water, often show non-Newtonian properties but remain poorly understood concerning the impacts of their rheological properties on fully developed turbulent structure. In this paper, we experimentally investigated resistance and momentum transport of hyper-concentrated sediment laden-flow in an open channel with two-dimensional square ribs by using Particle Image Velocimetry(PIV). The results showed that rheological properties significantly dissipated the turbulent flow fluctuations over the dune bed and augmented the flow resistance by comparison with the clear water flow.
Doboku gakkai ronbunshu, 2021
Proceedings of the International Conference on Civil, Structural and Transportation Engineering, Jun 1, 2022
In this study, a high-resolution, high-speed camera was used to capture driftwood velocity, while... more In this study, a high-resolution, high-speed camera was used to capture driftwood velocity, while PIV (particle image velocimetry) and PTV (particle tracking velocimetry) were used to measure free-surface velocity. The effects of channel slope, driftwood length and driftwood shape on the relative velocity between driftwood and free-surface flow were examined on the basis of an equation relating to driftwood motion and the experimental results. The study revealed that in cases where the driftwood angle is small, the velocity of a cylindrical piece of driftwood becomes higher than the free-surface velocity as channel slope and driftwood length increase. It was also found that the product of driftwood length and channel slope is proportional to the square of driftwood and free-surface velocity.
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Papers by Terunori Ohmoto