Keywords: Hydraulic model (two-dimensional), Permeable breakwater. 

 Vertical breakwater. Wave reflection. Wave transmission 



Wave motion through a permeable coastal structure such as a rip- 

 rap dike or a permeable breakwater is subject to resistance. If the 

 flow in a permeable structure is laminar, it is treated by considering 

 linear resistance. Such treatment is effective in the analysis of the 

 fluctuations of coastal ground water caused by the ebb and flow of tides, 

 and has produced satisfactory results in field tests for permeability 

 measurement . 



If the flow is turbulent due to short -period waves such as wind 

 waves, the resistance is a function of Reynolds number. The analysis of 

 such a flow can be made by approximating the nonlinear resistance term 

 with a linear relationship. A typical example of nonlinear resistance, 

 the wave motion in a vertical riprap dike, was adopted and a theoretical 

 study was made on the ratios of wave transmission and reflection due to 

 the structure. Experiments were also conducted to determine transmission 

 and reflection characteristics of a riprap dike constructed in a wave 

 channel . The results of these experiments show a good fit between experi- 

 mental and theoretical values. 



185. TOMINAGA, M., and SAKUMA, N., "Wave Overtopping on Coastal Dikes," 

 Report of the Public Works Research Institute, Ministry of Construc- 

 tion, Tokyo, Japan, Vol. 143, Sept. 1972, pp. 59-94 (in Japanese). 



Keywords: Concrete structures. Hydraulic model (two-dimensional). 

 Vertical breakwater. Wave overtopping 



Wave overtopping of breakwaters has been investigated experimentally 

 to obtain data to be used in the design of the height of these structures. 

 Various models of breakwaters were set on a beach with a slope of 1:30, 

 and the volume of wave overtopping was measured. Wave overtopping on ver- 

 tical walls was studied in detail; the effects of the front slope, parapet 

 wall, and wind were determined by comparisons with the results of the ver- 

 tical wall tests. 



The relationship between wave runup and wave overtopping was inves- 

 tigated, and a method of estimating wave overtopping was established. 

 The overtopping volume of the existing structure was calculated by this 

 method. It was found that wave absorbers should be placed seaward of 

 structures when the volume of wave overtopping is large. 



186. TOURMEN, L., "The Creation of an Artificial Beach in Larvotto Bay- 

 Monte Carlo, Principality of Monaco," Vroceedi-ngs of the 11th Con- 

 ference on Coastal Engineering ^ American Society of Civil Engineers, 

 Vol. 1, 1968, pp. 558-569. 



Keywords: Beach fill, Compartmented breakwater, Monaco (Larvotto Beach- 

 Monte Carlo), Structural dimensions. Submerged breakwater. 

 Wave attenuation. Wave diffraction 



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