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Water-Exchangable Caisson Design


The water-exchangeable type breakwater using short wave energy is one of choice for gentle sea condition due to simple geometry and the moderate construction costs (Sekimoto and Shimatani, 2000). This type of breakwater can be classified into two categories. One is conducting tube installed breakwater at the mean water level and another is slit caisson type breakwater.

We have been studied the optimal design of later type breakwater the last several yeas (Orihashi \textit{et al.}, 2003) and fund outgoing time-averaged current from inner harbor to outer ocean by wave and slit induced vortex interaction. However, the mechanism of seawater exchanging due to slit induced vortex is not still clear. The main difficulty understanding the seawater exchanging by the slit caisson is because of their complex relationship between geometry, slit induced jet (slit-jet) and large scale circulations around the slit. Therefore, it is important to understand the relationship between slit-jet induced circulations and breakwater geometry for optimal design of the water-exchangeable break water.

This project started early 2003 and still expanding to the future. The targets of this project are

  1. Numerical modeling of slit-caisson design
  2. Physical modeling of slit-caisson design
  3. Optimal design of slit-caisson
slit_cfd.gif Numerical Results using k-e model
slit_exp.gif Experimental Results using PIV measurements


  • Tsuneharu Orihashi, Penta Ocean Construction Co. Ltd., Japan
  • Shohachi Kakuno, OCU
  • Yasuhiro Kasai, OCU
  • Hiroaki Kashima, OCU

Project Results


  • References of Water-Exchangable Slit Caisson Design?