Response of the Wave Spectrum to Turning Winds

J. Ocean Eng. Technol. 1997;11(4):111-121.

풍향 변화에 대한 파랑 스펙트럼의 반응

윤종태

경성대학교 공과대학 토목공학과

Keywords: Wave Spectrum, Nonlinear Interaction, Duration Limited Growth, Discrete Interaction Approximation, Energy Balance Equation, Peak Frequency, Relaxation Process

핵심용어: 파랑 스팩트럼, 비선형 상호작용, 취송시간에 따른 성장, 이상 상호작용 가정, 에너지 평형 방정식, 첨두 주파수, 이완 과정

Abstract

The spectral energy balance model is composed and the nonlinear interaction is approximated by the discrete interaction parameterization as in WAM model. The numerical results of durational limited growth test agree very well with those of the exact model, EXACT-NL. The response of a wave spectrum to a change in wind direction is investigated numerically for a sequence of direction changes 30$^{circ}$ , 45$^{circ}$ , 60$^{circ}$ , 90$^{circ}$ . The high frequency components relax more repidly to the new wind direction than the low frequency components and the relaxation process also depends on the wave age. For wind direction changes less than 60$^{circ}$ , the coupling by nonlinear interaction is so strong that the secondary peak in input source distribution is counteracted by the negative lobe of the nonlinear interaction. For wind direction changes grater than 60$^{circ}$ , a second independent wind-sea spectrum is generated in the new wind direction, while the old spectrum gradually decays as swell.