An Analytical Solution of One Dimensional Mild Slope Equation by the WKB method

WKB 방법에 의한 일차원 완경사 파랑식의 해석해

  • Seo, Seung-Nam (Coastal Engineering & Ocean Energy Research Department, KORDI)
  • 서승남 (한국해양연구원 연안개발.에너지연구부)
  • Published : 2008.10.31

Abstract

An analytical solution of one dimensional mild slope equation is derived by use of the WKB method, which has a form similar to Porter's solution(2003). The present solution is so general in the sense of application that it is comparable to the corresponding numerical solutions. In the derivation we also presented the solution of refraction equation in terms of surface displacement. Some numerical results of the present solution by use of Bremmer's method are presented which agree with existing numerical solutions.

WKB 방법에 의한 일차원 완경사 파랑식의 해석해를 유도하였고 이는 Porter(2003)의 해와 유사한 형태를 갖는다. 적용적 측면에서 본 해석해는 관련 수치해에 견줄 만큼 해석상의 일반성을 갖는다. 유도과정에서 해면함수로 표현된 굴절 방정식의 해도 얻었다. Bremmer 방법을 이용한 본 해석해에 대한 수치계산 결과를 제시하였고 이들은 기존 결과와 일치한다.

Keywords

References

  1. 서승남 (2007a). Pade 근사에 의한 포물형 파랑 근사식 - 입사각 $80^{\circ}$까지 적용 모형. 한국해안해양공학회지, 19(4), 375-384
  2. 서승남 (2007b). 완경사 파랑식들의 재평가. 한국해안해양공학회지, 19(6), 521-532
  3. 서승남 (2008). 산란체법에 의한 다중 계단지형에서의 파랑 변형 계산. 한국해안해양공학회논문집, 20(5), 439-451
  4. 정태화, 서경덕 (2006). 축대칭 함몰지형 위를 진행하는 파의 변형에 관한 완경사 방정식의 해석 해. 한국해안해양공학회지, 18(4), 308-320
  5. Bremmer, H. (1951). The WKB approximation as the first term of a geometric optical series. Comm. Pure Appl. Math., 4, 105-115 https://doi.org/10.1002/cpa.3160040111
  6. Bender, C. M. and Orszag, S. (1978). Advanced Mathematical Methods for Scientists and Engineers, MaGraw-Hill, New York
  7. Berkhoff, J. C. W. (1972). Computation of combined refraction-diffraction. Proc. 13th Coastal Eng. Conf., 1, 471-490
  8. Booij, N. (1983). A note on the accuracy of the mild-slope equation. Coastal Eng., 7, 191-203 https://doi.org/10.1016/0378-3839(83)90017-0
  9. Chamberlain, P. G. and Porter, D. (1995). The modified mildslope equation. J. Fluid Mech., 291, 393-407 https://doi.org/10.1017/S0022112095002758
  10. Copeland, G. J. M. (1985). A practical alternative to the mildslope wave equation. Coastal Engng., 9, 125-149 https://doi.org/10.1016/0378-3839(85)90002-X
  11. Davies, A. G. and Heathershaw, A. D. (1984). Surface-wave propagation over sinusoidally varying topography. J. Fluid Mech., 144, 419-443 https://doi.org/10.1017/S0022112084001671
  12. Dean, R. G. and Dalrymple, R. A. (1984). Water wave mechanics for engineers and scientists. Prentice-Hall, Englewood Cliffs, New Jersey
  13. Holmes, M. K. 1995. Introduction to Perturbation Methods. Springer-Verlag, New York
  14. Jung, T.-H and Suh, K.-D. (2007). An analytic solution to the mild slope equation for waves propagating over an axisymmetric pit. Coastal Engng, 54, 865-877 https://doi.org/10.1016/j.coastaleng.2007.05.010
  15. Kajiura, K. (1961). On the partial reflection of water waves passing over a bottom of variable depth. Proc. Tsunami Meetings 10th Pacific Science Congress, IUGG Monograph. 24, 206-234
  16. Keller, J. B. (1958). Surface waves on water on non-uniform depth. J. Fluid Mech., 4, 607-614 https://doi.org/10.1017/S0022112058000690
  17. Lee, C., Park, W. S., Cho, Y. S. and Suh, K. D. (1998). Hyperbolic mild-slope equations extended to account for rapidly varying topography, Coastal Engng., 34, 243-257 https://doi.org/10.1016/S0378-3839(98)00028-3
  18. Liu, H.-W, Lin, P. and Shankar, N. J. (2004). An analytical solution of the mild-slope equation for waves around a circular island on a paraboloidal shoal. Coastal Engng., 51, 421-437 https://doi.org/10.1016/j.coastaleng.2004.04.005
  19. Mei, C. C. (1989). The Applied Dynamics of Ocean Surface Waves. World Scientific, Singapore
  20. Meyer, R. E. (1979). Surface-wave reflection by underwater ridges. J. Phys. Ocean., 9, 150-157 https://doi.org/10.1175/1520-0485(1979)009<0150:SWRBUR>2.0.CO;2
  21. Porter, D. (2003). The mild-slope equations. J. Fluid Mech., 494, 51-63 https://doi.org/10.1017/S0022112003005846