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Environmental Hydrodynamics

It is quite necessary in Hydraulic Engineering to investigate hydrodynamic characteristics in open-channel flows with various boundary conditions for preventing water-disaster, river environment and aquatic eco-systems. In particular, it is very important to reveal turbulence dynamics in such free-surface flows, because turbulence motions have great influences on momentum and sediment transport in rivers as well as gas-transfer at the free-surface region.

Therefore, our hydraulics laboratory are investigating the following topics.

  1. Turbulence Interaction between Air and Water at Free Surface
  2. 3D Turbulence Structure in Depth-varying Compound Open-Channel Flows
  3. Sediment Transport in Open-Channel Flows
  4. Hydrodynamic Characteristics in Open-Channel Flows with Side-Cavities
  5. Urban Flooding and Measures

Academic Staff

Keiichi TODA

Keiichi TODAProfessor (Graduate School of Engineering)

Research Topics

  1. Urban Flooding and Measures
  2. River Basin Management

Contacts

Room 255, Bldg. C1, Katsura Campus
TEL: +81-75-383-3185
FAX: +81-75-383-3185
E-mail: toda.keiichi.4z@kyoto-u.ac.jp

Michio SANJOU

Michio SANJOUAssociate Professor (Graduate School of Engineering)

Research Topics

  1. 3-D Numerical Analysis of Turbulent Structures in Depth-Varying Unsteady Compound Free-Surface Flows
  2. Generation and Development Process of Coherent Vortices in Depth-Varying Unsteady Two-Stage Flows
  3. Bed Shear Stress on Floodplain in Time-dependent unsteady flows with the transition stage from rectangular to compound channels

Contacts

Room 256, Bldg. C1, Katsura Campus
TEL: +81-75-383-3187
FAX: +81-75-383-3187
E-mail: michio.sanjou@water.kuciv.kyoto-u.ac.jp

Takaaki OKAMOTO

Takaaki OKAMOTOAssistant Professor (Graduate School of Engineering)

Research Topics

  1. Interaction between flow resistance and aquatic plant motion
  2. LIF measurements of turbulent diffusion in open-channel flows
  3. Large Eddy Simulation of 3-D Flow Structure in Open-Channel Flows with Vegetation

Contacts

Room 254, Bldg. C1, Katsura Campus
TEL: +81-75-383-3186
FAX: +81-75-383-3186
E-mail: takaaki.okamoto@water.kuciv.kyoto-u.ac.jp

Research Topics

Turbulence Interaction between Air and Water at Free Surface

This study focuses on air-water interfacial turbulence and scalar transfer phenomena across the interface in wind-induced open-channel flows. The study includes not only experimental measurements of air-water interfacial turbulent structures and the concentration of dissolved oxygen by several sets of laser Doppler Anemometers (LDA), Particle-image Velocimetry and DO meter, but also numerical prediction on two-fluid flows phenomena with multiphase incompressible immiscible materials. The goal of the study is to clarify the air-water turbulent phenomena and to evaluate the turbulent scalar transport with good accuracy by means of experimental approaches and the proposed numerical procedure.

photo : Measurement system for air-induced open-channel flow
Figure 1. Measurement system for air-induced open-channel flow

3-D Turbulence Structure in Time-dependent and Depth-varying Unsteady Open-channel flows

In compound open-channel flow that is composed of a main-channel and floodplains, there are considerable differences in primary velocities and turbulence at the junction between them. Because such hydrodynamic and turbulence features promote the transverse transport of momentum and various fluid scalars such as suspended sediments, it is quite necessary in hydraulic engineering and river environment to reveal the turbulent structure in compound open-channel flows. Many researchers have studied on compound open-channel flows by both the experimental and numerical methods.

However previous studies almost have been conducted on depth-fixed steady flows. Therefore, we have investigated the 3-D hydrodynamic characteristics in depth-varying unsteady compound open-channel flows by numerically and experimentally.

Our main researches are as follows:

  1. 3-D numerical analysis of turbulent structures in depth-varying unsteady compound open-channel flows
  2. Generation and development process of coherent vortices in depth-varying unsteady compound open-channel flows (by PIV measurements)
  3. Bed shear stress on floodplain in depth-varying unsteady flows with the transition stage from rectangular to compound channels (by LDA measurements)

image : 3-D structure of horizontal vortex in compound open-channel flow
Figure 2. 3-D structure of horizontal vortex in compound open-channel flow

Mechanism of Sediment Transport in Open-Channel Flows

In natural rivers, sand particles are moved by water flow near the bed. It is well known that a law of the flow resistance is influenced by sand-particle motions. Therefore, an investigation on interactions between the fluid and sediment particles in open-channel flows is quite important in hydraulics and river engineering.

photo : Sediment transport in open-channel
Figure 4. Sediment transport in open-channel

Hydrodynamic Characteristics in Open-Channel Flows with Side Cavities

In recent years, environmental functions in rivers have been attended. Therefore, maintenance and management policies for actual rivers are needed to consider various environmental problems. For example, “Wando” has been noticed as one of environmental hydraulic structures in actual rivers. Wand means a side-cavity in rivers, which is made by set groins in rivers bank. In and around Wando, variable aquatic eco-systems are formed.

However, Wando planning method is still in trial and error steps, and experimental or numerical calculation data will be necessary to establish the rational plan guidelines of Wando. So, we have been carrying out the turbulent measurements and analyzing flow properties in such Wando regions.

image : Open-channel flow with side cavity
Figure 5. Open-channel flow with side cavity

Urban Flooding and Measures

Unexpected flood disasters may occur in highly developed urban areas. We develop numerical simulation models and execute hydraulic experiments related to urban flood disasters.

The main research topics are as follows:

  1. Mechanism of urban flood disasters due to heavy rainfall, river flood or their combination.
  2. Analysis of inundation flow behavior in urban areas considering underground space.
  3. Experimental studies on car related problems in flooding.
  4. Design and evaluation of both structural and nonstructural measures against flood disasters.

Laboratory Website

http://www.water.kuciv.kyoto-u.ac.jp/