Wave-current-body interaction

We are motivated by, particularly, industrial needs for improved and cost-efficient design of offshore wind turbines. These are supported by relatively slender vertical columns, which may be fixed if the water is relatively shallow, or moored if the water is deep. An exhaustive, in depth and an internationally collaborative effort is under- taken, investigating the forces due to waves and currents that may act on a vertical cylinder in the sea environment. Experiments, development of new theories and com putation tools are combined in an analysis of kinematics of strong waves in shallow water and water of intermediate depth. Velocity fields of strong waves below and beyond breaking are measured in precise laboratory tank facility using high-speed Particle Image Velocimetry and compared to nonlinear computations. The estimated waves are used as input conditions to physical force measurements and calculations of the loads, the latter using various nonlinear potential formulation codes as well as Navier Sto kes solvers and Large Eddy Simulation computational tools, where the motion of the free surface is accounted for by a Volume of Fluid computational strategy. Of particular interest is the high-harmonic forces that occur in very strong waves. Also the com bined effect of waves and currents interacting with a vertical cylinder is investigated in the laboratory, by towing the cylinder in the incoming waves, developing in parallel a novel wave-current-body analysis to cubic order in nonlinearity. An ultimate goal of the pro ject is to perform several experimental runs in the physical laboratory with complementary computations using different methods and codes, providing a base of results of higher-harmonic loads on a vertical cylinder in any thinkable wave-c urrent condition at sea.