Interaction of hydro-elastic waves with a vertical wall

This study aims to gain knowledge on how hydroelastic waves interact with off-shore structures, for example off-shore wind turbines or oil rigs. The linear two-dimensional problem of hydroelastic waves reflected by a vertical wall is analysed. Water is of finite depth and is covered by ice. The fluid is assumed incompressible and inviscid. The ice sheet is assumed thin compared with both the water depth and length of the incident wave. Deflection of the ice sheet is described by linear elastic plate theory (see for example [1]), and fluid flow by using the potential flow model [5]. The ice sheet extends infinitely and is clamped to the verticalwalled structure. The incident hydroelastic wave is regular. The explicit solution for the ice deflection is derived, as well as the solution for the velocity potential in the fluid. We calculate several quantities of practical importance for off-shore structures in ice-covered waters, for instance the vertical shear force. The clamped ice introduces the vertical force acting on the structure in contrast to the more familiar problem of ice free floating on the water surface, where such force is absent. The vertical force is periodic in time and should be taken into account in the pre-design stage for such a structure. The magnitude of the vertical force is of the same order as that of the horizontal wave force component, which also is calculated. The horizontal force is analysed in detail to determine which terms in the model make the most contribution. Comparison is also made to the horizontal force of regular flexural gravity waves with no ice sheet present. The pressure on the wall and the bending stresses in the ice plate are also calculated.