14 research outputs found
流動性材料を用いた有限領域のダム破壊流れの基本特性とその応用に関する研究
No full text京都大学0048新制・課程博士博士(工学)甲第15344号工博第3223号新制||工||1485(附属図書館)27822京都大学大学院工学研究科都市社会工学専攻(主査)教授 細田 尚, 教授 後藤 仁志, 准教授 米山 望学位規則第4条第1項該当Doctor of Philosophy (Engineering)Kyoto UniversityDFA
Study of hydraulic properties of binary beads mixture as porous media in sustainable urban drainage system
No full text
Some Basic Considerations on the Development of High Velocity Flows in the Downstream of an Abrupt Expansion in a Steep Open Channel
No full textMathematical Modelling of One-Dimensional Overland Flow on a Porous Surface
No full textDue to rapid urbanization, surface water drainage systems are designed to perform as natural drainage acting as water storage areas that allow infiltration and evaporation and to solve issues caused by traditional drainage system As there is an increase of attention on Sustainable Urban Drainage system (SuDs) to manage storm water, a simple yet efficient numerical model for flow over porous media is needed. The purpose of this research is to develop a numerical model for the simulation of flow over porous media. The model solves the unsteady one-dimensional Saint-Venant equation for the surface flow. The advection term in the momentum equation is solved using the Constrained Interpolation Profile (CIP) scheme which is of the third order accuracy. Averaged infiltration rate is estimated from the physical model experiment. The model is then used to simulate dam-break flow over porous bed and the result is verified against the experiment. The author found that the numerical model performed satisfactorily in terms of surface flow profile and the loss of total fluid volume through infiltration
Insights into the flow characteristics of tsunami bores and surges: a case study of Malaysian coastline
No full textTsunamis, despite their rarity, are among the deadliest natural disasters, inflicting catastrophic damage on bothcoastal and inland regions. Given their highly site-specific impact, a comprehensive understanding of tsunamiwave flow characteristics is crucial for effective tsunami preparedness and for safeguarding civil engineeringstructures. This study investigates the formation and progression of tsunami bores as they transition into surgesnear the shore. We employed a wave-flume experimental approach, with a specific focus on the Malaysiancoastline. Experiments took place in a wave flume with a length of 40 m and a platform designed to replicatethe gentle slopes commonly found in Malaysian coastal areas vulnerable to tsunamis. The primary focus lied inmeasuring key flow parameters, including flow depths and velocities near the shore. Wet bed bores were markedby a sudden rise in water depth and considerable air entrainment in the front region. As these waves transformedinto dry bed surges, the front slope became gentler, and aeration diminished, while peak velocities increased.Additionally, the study also delves into the relations between flow depth and velocity concerning Froude numbersand momentum flux. The outcomes contribute significantly to global initiatives aimed at improving coastalresilience against tsunamis. 
A Fundamental Study of Supercritical Flow at Sudden Expansion Structure by Using Numerical Model
No full textIn the design of hydraulic structures, it is common to deal with the supercritical flow. Abrupt expansion structure represents a type of transition often constructed in manmade hydraulic structure (e.g. chutes in dam structures, sewer or drainage system, an irrigation channel, etc.) to cater the geometry difference. It is important to cater to the design of such transition especially it involves flow with high velocity. The flow features of high-velocity flow at sudden expansion channel are studied. A two-dimensional depth-averaged model (DA model) incorporate with Constrained Interpolation Profile (CIP) scheme is developed to simulate the supercritical flow at the abrupt expansion channel. The numerical model is able to reproduce the flow features of supercritical flow at the abrupt expansion structure. The simulated results are compared with the analytical solution with a different degree of agreement is observed. The same numerical setup is applied to the model generated by FLOW-3D model. The numerical results from the DA model and FLOW-3D model are compared with previous experimental results. The simulated results from the DA model showed better agreement with the experimental results
A Fundamental Study of Supercritical Flow at Sudden Expansion Structure by Using Numerical Model
No full textIn the design of hydraulic structures, it is common to deal with the supercritical flow. Abrupt expansion structure represents a type of transition often constructed in manmade hydraulic structure (e.g. chutes in dam structures, sewer or drainage system, an irrigation channel, etc.) to cater the geometry difference. It is important to cater to the design of such transition especially it involves flow with high velocity. The flow features of high-velocity flow at sudden expansion channel are studied. A two-dimensional depth-averaged model (DA model) incorporate with Constrained Interpolation Profile (CIP) scheme is developed to simulate the supercritical flow at the abrupt expansion channel. The numerical model is able to reproduce the flow features of supercritical flow at the abrupt expansion structure. The simulated results are compared with the analytical solution with a different degree of agreement is observed. The same numerical setup is applied to the model generated by FLOW-3D model. The numerical results from the DA model and FLOW-3D model are compared with previous experimental results. The simulated results from the DA model showed better agreement with the experimental results
Component Velocities and Turbulence Intensities within Ship Twin-Propeller Jet using CFD and ADV
No full textThis study presents the decays of three components of velocity for a ship twin-propeller jet associated with turbulence intensities using the ADV measurement and CFD methods. Previous research has shown that a single-propeller jet consists of a zone of flow establishment and a zone of established flow. Twin-propeller jets are more complex than single-propeller jets, and can be divided into zones with four peaks, two peaks, and one peak. The axial velocity distribution is the main contributor, and can be predicted using the Gaussian normal distribution. The axial velocity decay is described by linear equations using the maximum axial velocity in the efflux plane. The tangential and radial velocity decays show linear and nonlinear distributions in different zones. The turbulence intensity increases locally in the critical position of the non-interference zone and the interference zone. The current research converts the axial momentum theory of a single propeller into twin-propeller jet theory with a series of equations used to predict the overall twin-propeller jet structur
