• Title/Summary/Keyword: 2차 파강제력

Search Result 3, Processing Time 0.019 seconds

A Study on the Improvement of Wave and Storm Surge Predictions Using a Forecasting Model and Parametric Model: a Case Study on Typhoon Chaba (예측 모델 및 파라미터 모델을 이용한 파랑 및 폭풍해일 예측 개선방안 연구: 태풍 차바 사례)

  • Jin-Hee Yuk;Minsu Joh
    • Journal of Korean Society of Coastal and Ocean Engineers
    • /
    • v.35 no.4
    • /
    • pp.67-74
    • /
    • 2023
  • High waves and storm surges due to tropical cyclones cause great damage in coastal areas; therefore, accurately predicting storm surges and high waves before a typhoon strike is crucial. Meteorological forcing is an important factor for predicting these catastrophic events. This study presents an improved methodology for determining accurate meteorological forcing. Typhoon Chaba, which caused serious damage to the south coast of South Korea in 2016, was selected as a case study. In this study, symmetric and asymmetric parametric vortex models based on the typhoon track forecasted by the Model for Prediction Across Scales (MPAS) were used to create meteorological forcing and were compared with those models based on the best track. The meteorological fields were also created by blending the meteorological field from the symmetric / asymmetric parametric vortex models based on the MPAS-forecasted typhoon track and the meteorological field generated by the forecasting model (MPAS). This meteorological forcing data was then used given to two-way coupled tide-surge-wave models: Advanced CIRCulation (ADCIRC) and Simulating Waves Nearshore (SWAN). The modeled storm surges and waves correlated well with the observations and were comparable to those predicted using the best track. Based on our analysis, we propose using the parametric model with the MPAS-forecasted track, the meteorological field from the same forecasting model, and blending them to improve storm surge and wave prediction.

A Nonlinear Response Analysis of Tension Leg Platforms in Irregular Waves (불규칙파중의 인장계류식 해양구조물의 비선형 응답 해석)

  • Lee, Chang-Ho;Gu, Ja-Sam;Jo, Hyo-Je;Hong, Bong-Gi
    • Journal of Ocean Engineering and Technology
    • /
    • v.12 no.2 s.28
    • /
    • pp.33-42
    • /
    • 1998
  • In the presence of incident waves with different frequencies, the second order sum and difference frequency waves due to the nonlinearity of the incident waves come into existence. Although the magnitudes of the forces produced on a Tension Leg Platform(TLP) by these nonlinear waves are small, they act on the TLP at sum and difference frequencies away from those of the incident waves. So, the second order sum and difference frequency wave loads produced close to the natural frequencies of TLPs often give greater contributions to high and low frequency resonant responses. The second order wave exciting forces and moments have been obtained by the method based on direct integration of pressure acting on the submerged surface of a TLP. The components of the second order forces which depend on first order quantities have been evaluated using the three dimensional source distribution method. The numerical results of time domain analysis for the nonlinear wave exciting forces in regular waves are compared with the numerical ones of frequency domain analysis. The results of comparison confirmed the validity of the proposed approach.

  • PDF

Depth Control of a Submerged Body Near the Free Surface by LQR Control Method (LQR 제어 기법을 적용한 수면 근처에서의 수중운동체 심도 제어)

  • Kim, Dong-Jin;Rhee, Key-Pyo;Choi, Jin-Woo;Lee, Sung-Kyun
    • Journal of the Society of Naval Architects of Korea
    • /
    • v.46 no.4
    • /
    • pp.382-390
    • /
    • 2009
  • The submerged body near the free surface is disturbed by the 1st and 2nd order wave forces, which results in unstable movements when no control is applied. In this paper, the vertical motions of the submerged body are analyzed, and the time-variant nonlinear system for the vertical motions of the submerged body is transformed to the time-invariant linear system in state space. Next, depth controller of the submerged body is designed by using LQR control, one of the modern optimal control technique. Numerical simulation shows that effective depth controls can be achieved by LQR control.