Numerical Study On The Response Of Harbors To Various Initial Disturbance

With the development of the port engineering, it becomes very important in the national economy. But as for the complicated marine environmental conditions, the safety of the harbor is put forward as the first state. Due to the influence of random waves from the open sea, fluctuations of atmosphere pressure, wind, tidal and so on, the harbor oscillations are likely to happen in the port, which are harmful for the berthing or mooring conditions, and directly affect the normal port operations service. The harbor resonance must be considered in the process of designing and planning port.First of all, the paper presents the harbor oscillation’s background and illustrates the domestic and foreign scholars’research progress and development trend about the harbor resonance problems of mathematical model and physical model. Secondly, MIKE21-BW mathematical model is introduced in this paper; The model is based on the improved Boussinesq equations; Boussinesq equations and its numerical solution is presented and the wave model and the boundary layer of the MIKE21-BW module are stated. The paper uses MIKE21-BW module to simulate the of rectangular, circle, coupled circle, arbitrarily harbor and closed circle harbor oscillations excited by the solitary wave, N-wave and initial Gauss-shaped surface, and the simulation results are analyzed. The propagation of a solitary wave into a harbor induces a transient disturbance and the solitary wave is reflected. The analysis results based on the continuous wavelet transform show that the energy of the disturbance caused by the solitary wave concentrates at the first eigen frequency of the harbor. The propagation of a N-wave into a harbor also induces a transient disturbance and the N-wave is reflected, but the disturbance is more severe and lasts longer than the solitary wave. The analysis results through the continuous wavelet transform show that the energy of the disturbance caused by the solitary wave also concentrates at the first eigen frequency of the harbor. In addition, the energy of the disturbance caused by the N-wave concentrates at the different eigen frequencies of the circle harbor inside and outside. At last, the paper studies on the closed and open circle harbor oscillations excited by an initial Gauss-shaped surface. For the closed circle harbor the method of the paper is not fit. For another harbor the diverse of initial positions can induce the different eigen frequencies.