Journal of the Korean Society of Marine Environment & Safety (해양환경안전학회지)

The Korean Society of Marine Environment and safety (해양환경안전학회)
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Damping of Water Waves over Permeable Bed of Finite Depth

유한한 깊이의 투수층에 의한 파랑의 감쇠

  • Kim, Gun-Woo (Department of Ocean Civil & Plant Construction Engineering, Mokpo National Maritime University) ;
  • Lee, Myung-Eun (Department of Civil and Environmental Engineering, Seoul National University)
  • Received : 2012.05.15
  • Accepted : 2012.06.25
  • Published : 2012.06.30
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Abstract

In this study, wave transformation by damping due to the permeable bed of finite depth is investigated. The relationship between wave damping rate and relative water depth are presented. The damping rate is used in the eigenfunction expansion method to calculate the wave dissipation over the permeable bed. For a permeable shoal, the eigenfunction expansion model result is compared with that of the integral equation method to show good agreement. The model is also used to examine the wave reflection over the permeable planar slope of various frequency. It has been found that in general relatively short waves are more influenced by the permeability of the permeable seabed than relatively long waves unless the water depth is so large that the influence of permeable bed on surface water waves disappears.

본 연구에서는 유한한 깊이의 투수층에 의한 에너지 감쇠효과를 고려한 파랑의 변형을 해석하였다. 파의 에너지 감쇠율과 상대수심의 관계식을 제시하였으며, 에너지 감쇠율을 고유함수전개법에 사용하여 투수층에 의한 에너지 감쇠를 계산하였다. 투수성이 있는 수중둔덕에 대해서, 수치실험 결과는 해석해로 간주할 수 있는 적분방정식의 결과와 비교하여 잘 일치하였다. 또한, 투수경사에 의한 반사율을 다양한 주파수에 대해서 실험하였으며, 수치실험 결과, 수심이 매우 커서 수면파가 투수층의 영향을 받을 정도가 아닌 경우에는 상대적으로 파장이 짧은 파랑일수록 투수층의 영향을 크게 받는 것으로 나타났다.

Keywords

References

  1. Booij, N.(1983), A note on the accuracy of the mild-slope equation, Coastal Engineering, Vol. 7, pp. 191-203. https://doi.org/10.1016/0378-3839(83)90017-0
  2. Do, K. D. and K. D. Suh(2011), Wave damping over a multilayered, permeable seabed, Journal of Coastal Research, Vol. 27, No. 6, pp. 1183-1190.
  3. Flaten, G. and O. B. Rygg(1991), Dispersive shallow water waves over a porous sea bed, Coastal Engineering, Vol. 15, pp. 347-369. https://doi.org/10.1016/0378-3839(91)90016-A
  4. Guazzelli, E., V. Rey and M. Beizons(1992), Higher-order Bragg reflection of gravity surface waves by periodic beds, Journal of Fluid Mechanics, Vol. 245, pp. 301-317. https://doi.org/10.1017/S0022112092000478
  5. Kirby, J. T. and R. A. Dalrymple(1983), Propagation of obliquely incident waves over a trench, Journal of Fluid Mechanics, Vol. 133, pp. 47-63. https://doi.org/10.1017/S0022112083001780
  6. Liu, P. L. F. and R. A. Dalrymple(1984), The Damping of gravity water waves due to percolation, Coastal Engineering, Vol. 8, pp. 33-49. https://doi.org/10.1016/0378-3839(84)90021-8
  7. O'Hare, T. J. and A. G. Davies(1992), A new model for surface-wave propagation over undulating topography, Coastal Engineering, Vol. 18, pp. 251-266. https://doi.org/10.1016/0378-3839(92)90022-M
  8. Reid, R. O. and K. Kajiura(1957), On the damping of gravity waves over a permeable seabed, Transactions of American Geophysical Union Vol. 38, pp. 662-666. https://doi.org/10.1029/TR038i005p00662
  9. Takano, K.(1960), Effects d'un obstacle paralellelepipedique sur la propagation de la houle, Houille Blanche, Vol. 15, p. 247.

Cited by

  1. Development of Complementary Mild-slope Equation for Stream Function Over Permeable Bed vol.22, pp.6, 2016, https://doi.org/10.7837/kosomes.2016.22.6.758