Journal of Korean Society of Coastal and Ocean Engineers (한국해안·해양공학회논문집)

Korean Society of Coastal and Ocean Engineers (한국해안·해양공학회)
권호 표지

사다리형태로 변화하는 지형 위를 통과하는 파군에 의한 장파의 생성

Long Waves Generated by Wave Groups over Trapezoidally Varying Topography

  • Published : 2008.04.30
Download PDF
⟨ Previous Next ⟩

Abstract

A possible source of resonant problems in a harbor is long waves generated by incident wave groups. The analytical solutions of the governing equations of second-order long waves derived using a multiple-scale perturbation method consist of the locked and free long waves. The locked long waves propagate at some group velocity, whereas the free long waves propagate at the shallow-water speed. To study the resonance of free long waves, a trapezoidally varying topography is employed. With certain combinations of incident angle, water depth, and ambient current velocity, free long waves can be trapped and resonated.

입사파의 파군에 의해 생성되는 장파는 항내에서 부진동의 문제를 발생시킬 가능성이 있다. 다변수 섭동법을 사용하여 구속장파와 자유장파로 구성된 2차 장파에 관한 지배 방정식의 해석 해를 유도하였다. 자유 장파의 경우 천해역에서의 파속도로 진행하는 반면 구속 장파의 경우 군속도로 진행한다. 장파의 의한 공명을 조사하기 위하여 사다리형태로 변화하는 지형을 고려하였다. 파의 입사각, 수심, 또는 유속에 의하여 자유 장파의 갇힘과 공명현상이 발생하였다.

Keywords

References

  1. Agnon, Y. and Mei, C.C., 1985: Slow drift motion of a twodimensional block in beam seas. J. Fluid Mech., Vol. 151, pp. 279-294 https://doi.org/10.1017/S0022112085000969
  2. Bender, C.M. and Orszag, S.A., 1987: Advanced mathematical methods for scientists and engineers, 3rd edition. McGraw Hill Inc., USA
  3. Cho, Y.-S., Chae, J.-W. and Cha, Y.-K., 1996: Long waves generated by short wave groups: Derivation of governing equations. KSCE, Journal of Civil Engineering, Vol. 16, No. -4, pp. 389-397 (in Korean)
  4. Cho, Y.-S., and Lee, C., 1998: Calculation of reflection and transmission coefficients of waves over a varying topography. KSCE, Journal of Civil Engineering, Vol. 18, No. II- 4, pp. 351-358
  5. Liu, P.L.-F. and Cho, Y.-S., 1993: Bragg reflection of infragravity waves by sandbars. J. Geophy Res., Vol. 98, pp. 22,733-22,741
  6. Liu, P.L.-F., Cho, Y.-S., Kostense, J.K. and Dingemans, M.W., 1992: Propagation and trapping of obliquely incident wave groups over a trench with currents. Appl. Ocean Res., Vol. 14, pp. 201-213 https://doi.org/10.1016/0141-1187(92)90015-C
  7. Liu, P.L.-F., Dingemans, M.W. and Kostense, J.K., 1990: Long wave generation due to the reflection of short-wave groups over a shear current. J. Phys. Oceanography, Vol. 20, pp. 53-59 https://doi.org/10.1175/1520-0485(1990)020<0053:LWGDTT>2.0.CO;2
  8. Mei, C.C., 1989: The applied dynamics of ocean surface waves, World Scientific., USA
  9. Mei, C.C. and Agnon, Y., 1989: Long-period oscillation in a harbour induced by incident short wave. J. Fluid Mech., Vol. 208, pp. 595-608 https://doi.org/10.1017/S0022112089002958
  10. Roelvink, J.K. and Stive, M.J.F., 1989: Bar-generating crossshore flow mechanism on a beach. J. Geophy. Res., Vol. 94, pp. 4785-4800 https://doi.org/10.1029/JC094iC04p04785
  11. Symonds, G. and Browen, A.J., 1984: The interaction of nearshore bars with incoming wave groups. J. Geophy. Res., Vol. 89, pp. 1953-1959 https://doi.org/10.1029/JC089iC02p01953
  12. Zhou, C. and Liu, P.L.-F., 1987: Second-order low-frequency wave forces on a vertical cylinder. J. Fluid Mech., Vol. 175, pp. 143-155 https://doi.org/10.1017/S0022112087000338