Abstrakt

The offshore wind turbines require determination of wave loads on their support structure. This structure is fixed and, therefore, this problem is reduced to solving only the diffraction problem, which is determined by Laplace equation and conditions on the following boundaries: on the support structure, on the sea free surface and on its bottom, and at infinity on free surface. The linear problem was applied to determine the wave loads. The assumption of the solution of the problem has a form of single potential layer which converts the differential problem into Fredholm equation of second kind. This ap- proach is based on the Green function satisfying the condition on the sea free surface and on its bottom (finite depths), there- fore, it is enough to fulfill the boundary condition on a support structure. In numerical solution, the discretization of the tower surface into boundary elements (panels) is only required. The algorithm developed, based on the Boundary Element Method, requires verification. In this purpose as a form of wind support structure the cylinder was used, for which exact solution of the diffraction problem exist. In the verification, wave pressures distributed on the cylinder surface and generated forces and moments, obtained in numerical solution of the problem have been compared with the exact theoretical results. The numeri- cal and theoretical results were well compared, and was concluded that the algorithm developed can be applied to the wind support structure of more complicated forms. In this paper the following is presented: the differential problem and Fredholm equation determining the diffraction problem, tables and graphs showing the comparison of the theoretical and numerical results, conclusions for further work.

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