The Model Of Solution To MSE When Calculating Wave Incident Direction At Boundary

On the basis of the linear wave theory, aiming at how to numerically simulate the irregular wave refraction and diffraction accurately, this paper developed an adaptive finite element method which fits to the mild slope topography and complex boundary conditions.Based on the Berkhoff elliptic mild slope equation and a series of boundary conditions, the model is used to effectively simulate irregular bathymetry and different frequency wave propagation so that a preconditioning program which can obtain optimal meshes in terms of different bathymetry and wave length is developed in this paper. In order to reduce storage requirement and save computer expense, the index-storage method and conjugate gradient method are employed to solve the large sets of simultaneous equations. Moreover, the prior error estimation , Z~2 posterior error estimation and an adaptive remeshing method based on the h-method are used to improve numerical accuracy.The mild-slope equation (MSE) is a preferable numerical model to simulate wave propagation near shore. According to developed self-adaptive finite element method, this paper uses an iterative method to ascertain wave incident direction which is between the incident wave direction and the normal vector to the partial reflective boundary, then sequentially takes improvement to the absorptive boundaries, so that sets up a proper numerical model to solve the MSE. Taking the wave direction into account, the ability of this method to simulate waves in some typical cases and behind a breakwater gap is examined. The results are more accurate and fitter to the experiment than those which don't calculate the wave direction.Besides, this paper simulates the wave diffraction around a semi-infinite breakwater and through a breakwater gap. The results show that the wave directional spreading has a definite effect on the wave diffraction. In engineering sense, the effects of the wave directional spreading on the wave diffraction can be neglected when the directional spreading parameter s is bigger than around 45.