Tetsuya Hiraishi

Computation of Wave Transfomation in Area with Permeable Breakwater and Hydraulic Model Test

To prevent water pollution inside a port, a breakwater with piercing slits is developed. The wave transmission of the breakwater should be considered in the computatio of wave transformation in the target port. The proposed simulation model is verified by the model test.

Experimental Study for Directional Wave Force on a Column

Real sea wave is quite random in amplitndes, periods and propagating directions. Offshore sea waves, therefore, have characteristics of “directional randomness”. Directional random waves in the offshore consist of the component waves each propagating in different directions in shallow area. Some coastal structures constructed in deep water area should be designed for directional random waves. The experiment for the directional wave force are done. The target structure is a column, which is the simplest component in coastal structures. The wave force on a column in directional seas is compared with that in uni-directional waves.

Frequency Response of Seabed around Anchor due to Steady-State Mooring Force

In the analysis of soil-structure interaction problems, the ground is typically modelled by either an elastic or a visco-elastic medium.It may be more suitable. however, to assume a fluid-filled porous material for seabed.The frequency response of seabed around an end bearing anchor due to steady-state mooring force is numerically evaluated by assuming the seabed as a fluid-saturated poroelastic halfspace whose behavior is governed by Biots theory, and depends on the permeability of seabed and the load carrying share of pore fluid to acting force.In this paper, these effects to frequency response of seabed are investigated through some numerical examples.

Experimental Study on Wave Transmission and Reflection of Flexible Floating Board

A long flexible floating board made of the complex of needle-trees has been developed to moor small vessels like pleasure boats. The present paper investigates experimentally the wave transmission and left-lettlection of the board. The transmission coefficient KT and left-lettlection coefficient KR do not depend on the relative width of the board (width/wave length) but on the incident wave steepness. The value of KT decreases and KR increases as the wave steepness becomes large. The wave transmission coefficient becomes much smaller as the draught of the front float is deepened.