The subject of interaction hydrodynamics between two floating bodies or between a floating body and an offshore structure is briefly reviewed in this paper. The mathematical model based on the energy principle is discussed first. In this model, the kinetic energies of an ice floe and the associated added mass are assumed to be constant before the impact, and are transformed entirely into work done in crushing the ice floe. Thus, the ice floe is stopped by the offshore structure after the impact, and the impact is assumed to be head-on. The general formulation for the hydrodynamic interaction between two bodies with or without rotation is then presented based on the Lagrange equations of motion. Numerical results are obtained for the trajectory of the moving body and the hydrodynamic interaction force on the fixed body.
Floating, monolithic ice masses, such as annual sea-ice floes, multiyear floe bergs, or glacier-ice icebergs, pose a major obstacle to offshore development as well as naval operations in the arctic region. As a large, floating ice floe approaches an offshore structure, the current conveying the ice mass is deflected either completely (for gravity-based structures) or partially (for floating structures) around the structure. However, even in the case of gravity-based structures (GBS), in which all of the fluid must pass around the structure, there is no assurance that a large ice mass will not impact the structure. This is because the trajectory of the ice mass is not the same as the pathlines when the latter are curved. The fluid may be deflected around the structure, but the ice floe that it is transporting may be "centrifuged" out of the transporting flow and impact the structure. Earlier mathematical models for predicting ice impact forces on offshore structures were based on the energy principle.
