Grant-in-Aid for Scientific Research (C).
|Research Institution||Gifu University|
YASUDA Takashi Gifu Univ., Grad. Course of Enviro. & Renewable Energy Sys., Prof., 工学部, 教授 (10093329)
TANAKA Mitsuhiro Gifu Univ., Dept. of Civil Eng., Assoc. Prof., 工学部, 助教授 (70163582)
MUTSUDA Hidemi ditto, Re. Assoc., 工学部, 助手 (80273126)
SAKAKIBARA Yukio Toyota Tech. College, Dept. of Civil Engrg., Assit. Prof., 講師 (50249801)
KOBAYASHI Tomonao ditto, Assoc. Prof., 工学部, 助教授 (50205473)
|Project Fiscal Year
1998 – 1999
Completed(Fiscal Year 1999)
|Budget Amount *help
¥3,000,000 (Direct Cost : ¥3,000,000)
Fiscal Year 1999 : ¥700,000 (Direct Cost : ¥700,000)
Fiscal Year 1998 : ¥2,300,000 (Direct Cost : ¥2,300,000)
|Keywords||Wave breaking / Breaking wave jet / Breaking wave process / Wave absorption / Entrained air bubble / Coherent eddies / 砕波 / 水面波ジェット / 砕波過程 / 消波 / 気泡 / 大規模渦|
1) Generation condition and characteristics of a breaking wave jet
Investigations were made on changes of water surface profiles and velocity fields in jet formation process of a solitary wave breaking on a uniformly sloping bottom and reef. It was found that the size of the breking wave jet depends on shoaling effect and becomes a paradmeter governing horizontal asymmetry of wave motion.
2) Breaking wave processes after the plunging of a overturning jet and their internal kinematics.
Hydraulic-experimental and numerical investigations were made on transient processes from large-scale coherent eddies generated by the plunging jet to small-scale turbulent eddies. It was made clear that the sizes of the coherent eddies and entrained air bubbles are in linear relations with the jet size parameter and a theoretical approach on the breaking wave processes becomes possible only if the size of an overturning jet can be evaluated by a wave model before breaking.
3) Influences of the plunging jet o
n energy dissipation and momentum transfer in wave breaking processes
Investigations were made on a transmission coefficient related to dissipation and wave set-up caused by momentum transfer in random wave breaking processes on reef. It was found that the transmission coefficient and wave set-up are governed by the kinematics of a jet ejected from each crest but can be treated by such statistics as significant wave height.
4) Generation condition and characteristics of jet ejected from shallow water breaking wave.
Relationships of jet generation condition to incident wave parameters, bottom topography and overturning jet kinematics were made clear through the numerical simulations using the Boundary Integral Method.
5) Relationships between kinematics of plunging jet and breaking wave process after the plunging.
It was found that there is a unique relation between the size and the horizontal velocity of overturning jet and about 80% of the momentum of the plunging jet is absorbed into the development of spray.
6) Modelling of breaking wave process after the jet plunging
It was verified in comparison with hydraulic-experimental results that a model using the VOF method with the κ-ε model is applicable to the breaking wave process.