Ryuichi Fujiwara

A METHOD FOR ESTIMATING STANDARDIZED BIMODAL DIRECTIONAL SPECTRA

A study of alternatives including a shoreline evolution numerical modelization has been carried out in order to both diagnose the erosion problem at the beaches located between Cambrils Harbour and Pixerota delta (Tarragona, Spain) and select nourishment alternatives.

FIELD EXPERIMENTAL PROJECT OF FLAP-GATE BREAKWATER FOR TSUNAMI AND STORM SURGE PROTECTION

A flap-gate breakwater for tsunami and storm surge protection was previously developed through hydraulic model experiments and numerical simulations. In this study, applicability of the flap-gate breakwater through a field experiment is shown. Although the field experiment is carrying out at Yaizu fishing port in Shizuoka prefecture, Japan, some technical investigations have been obtained. Feasibility of maintenance and characteristics of age deterioration and corrosion will be verified through continuous experiments to be conducted in the future.

A Numerical study for Overtopping over a Seawall Having a Detached Upright Wave-absorbing Works

(1)CADMAS-SURFの概要 数値シミュレーションに用いたCADMAS-SURFの詳細 は先述の文献を参照していただきたいが,以下に特徴を 簡単に示す. 基礎方程式には,海底斜面や透過性構造物等の複雑な 形状を取り扱うため,二次元非圧縮性粘性流体を対象と した連続式およびNavier-Stokes方程式をポーラスモデル に基づいて拡張した式が採用されている.座標系はデカ ルト座標系で,方程式はスタガード格子系を用い差分化 されている.また,自由表面解析モデルには,汎用性が 高く,複雑な表面形状を取り扱うことができるVOF法が 用いられている,その他,造波モデル,無反射モデルお よび乱流モデル等が組み込まれている. 直立透過式構造物を消波工とした遊水部を持つ 直立護岸の越波低減機能 A Numerical study for Overtopping over a Seawall Having a Detached Upright Wave-absorbing Works

A COUNTERMEASURE AGAINST WAVE-OVERTOPPING USING SCRAP CONCRETE OF DAMAGED SEAWALLS

A lot of inundation of sea water has arisen at coastal zone in Japan recent years because of attacking larger tidal waves and storm surges than usual. Also there are many examples that a destruction of parapet could cause serious damage by increasing of overtopping to the coastal zone. When seawalls have been damaged, a lot of scrap concrete is generated. In this study, a countermeasure against wave overtopping using these scrap concrete of damaged seawalls is proposed and verified the validity of the facilities and equipments for countermeasures against disaster by hydraulic model tests. Furthermore a method for estimating overtopping over seawalls using CADMAS-SURF has applied to the model test and validated .

Application of Standardized Bimodal Directional Spectra to Field and Laboratory Data

Directional spectra sometimes have two peak directions due either to waves fxom two generation areas, or to incident and reflected waves. In the present study, a method for estimating standardized bimodal directional spectra for a three-component array which measures the water surface elevation and two components of the water particle velocity is applied to field and laboratory data. Furthermore, a method for estimating directional spectra in a field of incident and reflected waves is also developed and applied to the data. The validity of these methods is confirmed through the applications.