The wave diffraction in a current around a large-scale vertical circular cylinder is studied numerically in this paper. The wave relative frequency in the coordinate system moving with current and the angle between the direction of wave propagation and that of current are computed based on the wave dispersion relation. The current field is computed by solving the shallow water equation. The wave field is computed by solving the Mild Slope Equation that has taken the current's affect into account. The coupling result is obtained by iterative calculation of above two fields. A numerical model is established using a Finite Element Method for simulating the wave diffraction in a current around a large-scale vertical circular cylinder, the numerical results are reasonable to compare with the experimental data.
The parameters and direction of waves are usually changed due to the influence of current action in coastal zone. The wave-current field around the structure must be calculated if the structure is gonging to construct in this zone. Tidal current can be considered as stationary because its scale is large enough to compare with wave field. So the essential of this problem is the solution of the combined wave and stationary current field. A lot of studies have been carried in the situation of D/L<0.2, where D is the cylinder diameter, L is the wavelength. When D/L>0.2, there is the effect of wave diffraction. There is a few research related to this topic because of severe disturb among waves, current, and structure, especially around the cylinder. At present, the wave field and current field usually are calculated separately in engineering design. The wave field is calculated by linear theory, in which the wave factors are influenced due to current, and the current field is calculated as circuitous current.
