- Volume 39 Issue 8
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Characteristics of wave propagation in a sloping-wall-type wave absorber
- Zhu, Lixin (School of Mechanical Engineering, Pusan National University) ;
- Lim, Hee Chang (School of Mechanical Engineering, Pusan National University)
- Received : 2014.11.13
- Accepted : 2015.08.08
- Published : 2015.10.31
The objective of this study is to observe and optimize a typical ocean environment and reduce wave reflections in the wave flume. In order to generate ocean waves in the wave flume, a combination of a horizontal piston type wave generator and wave absorbers was installed in the channel. Two probes for measuring the wave heights, i.e., wave level gauges, were used to record the continuous variation of the wave surface, the phase difference, and the maximum (crest) and minimum (trough) points of the propagating waves. In order to optimize the shape and size of the propagating waves, several absorption methods were proposed. Apart from an active wave absorption method, we used methods that involved vertical porous plates, horizontal punching plates, and sloping-wall-type wave absorbers. To obtain the best propagating waves, a sloping-wall-type wave absorber was chosen and tested in terms of the constitutive filling materials and the location and shape of the plate. This study also focused on the theoretical prediction of the wave surface, separating them into the incident and reflective components. From the results, it is evident that the wave absorber comprising a hard filling material exhibits a better performance than the absorber comprising a soft material, i.e., the wave absorber can be a strong sink to control the energy of the incoming wave. In addition, larger wave absorbers correspond to lower reflectance because a larger volume can reduce the incoming wave energy. Therefore, at constant absorber conditions, the reflectance of the wave increases as the wave period increases. Finally, the reflectance of the wave was controlled to be less than 0.1 in this study so that the wave flume can be used to simulate an offshore environment.
Supported by : Pusan National University
- J. J. Healy, "Wave damping effect of beaches," Proceedings of the Minnesota International Hydraulics Convention, pp. 213-220. 1952.
- Y. Goda, Y. Suzuki, "Estimation of incident and reflected waves in random waves," Proceedings of the fifteenth Conference on Coastal Engineering, ASCE, New York, pp.828-865. 1976.
- C. J. Galvin, Wave Height Prediction for Wave Generators in Shallow Water, U.S. Army, Coastal Engineering Research Center, 1964.
- L. Greslou and Y. Mahe, "Etude du coefficient de reflection dune sur un obstacle constitue par un plan incline," Proceedings of the Fifth Conference on Coastal Engineering, pp.68-83, 1954.
- E. F. D. Masard and E. R. Funke, "The measurement of coexisting random wave energy," Proceedings of the fifteenth Conference on Coastal Engineering, ASCE, New York., 1980.
- P. A. Madsen, "Wave reflection from a vertical permeable wave absorber," Coastal Engineering, vol. 7, no. 4, pp. 381-396, 1983. https://doi.org/10.1016/0378-3839(83)90005-4
- S. H. Kwon, W. M. Moon, and H. S. Lee, "Experimental and numerical studies on the development of a new wave absorber," Ocean Engineering, vol. 30, no. 1-2, pp. 185-203, 2003. https://doi.org/10.1016/S0029-8018(02)00019-7
- V. Mallayachari and V. Sundar, "Reflection characteristics of permeable seawalls," vol. 23, no. 1-2, Coastal Engineering, pp. 135-150, 1994. https://doi.org/10.1016/0378-3839(94)90019-1
- R. A. Dalrymple, M. A. Losada, and P. A. Martin, "Reflection and transmission from porous structures under oblique wave attack," Journal of Fluid Mechanics, vol. 224, pp. 625-644, 1991. https://doi.org/10.1017/S0022112091001908