Seiche Characteristics of Gun-Jang Harbor

J. Ocean Eng. Technol. 2008;22(1):46-52.

Cho Yong-Jun,Park Hyung-Soo

Dept. of Civil Engr University of Seoul,Dept. of Civil Engr University of Seoul

군장항의 부진동 특성

조용준,박형수

서울시립대학교 토목공학과,서울시립대학교 토목공학과 대학원

Keywords: Seiche, Natural frequency, Response spectrum of inner harbor, Entrance head loss, Harbor paradox

핵심용어: 부진동, 고유진동수, 항 내 응답스펙트럼, 유입부 손실, 항 역설

Abstract

Lately Gun-Jang Harbor has undergone a drastic change in hydraulic characteristics due to newly added harbor protection measures, like a wharf and breakwater. The wharf and breakwater, with a training dike, were constructed to keep enough depth far navigation. They make the plan view of Gun-Jang Harbor semi closed and very elongated, which makes it very vulnerable to seiche. Hence it is an urgent task to unveil the hydraulic characteristics, like seiche, for the optimal operation of the new harbor system. In this study, we numerically analyze the seiche characteristics of Gun-Jang Harbor over the $10-4{sim}10-3$ Hz frequency range, considering that wind waves due to seasonal winds are the most prevailing during winter in the West sea. As a wave driver, we use Mild Slope Eqs. and numerically integrate these using FEM based on Galerkin weak formulation. It turns out that the 1st, 2nd, 3rd and 4th eigen models are over 0.0009 Hz, 0.0013 Hz, 0.0017 Hz and 0.002 Hz.