Case Studies III

Most offshore wind turbine structures are built with monopile type structures where some marine operations are conducted nearby. Therefore, proper wave estimation around the monopile is needed to assure safe marine operations. The trend of increasing monopile's diameter also adds the need to investigate the wave field around the increased monopile diameter. Experimental campaigns of wave field around a monopile in irregular incident waves with different steepness are reported in this study to extend avalaible experiments which focused mostly on the runup of cylindrical structures. Wave elevations at two radial positions and six angular positions around the monopile are highlighted. The results are processed to obtain the Linear Transfer Function of wave field around the monopile and the exceedance probability of the crests and wave height of the waves. Linear solution is seen to be able to capture the wave height but the crests exceedance probability.

Ship propellers generate high-flow velocities near quay walls, posing risks of bed scour and structural instability. A joint effort by CROW and the Dutch Government aims to refine bed protection design. This research program combines field measurements, scale model tests, and numerical modeling. At Deltares, a scale model investigates confined propeller jets from large vessels. Particle Image Velocimetry (PIV) characterizes propeller jet-induced flow fields, near-bed velocities, and turbulence levels. Deformation tests assess the stability of various bed protections, including conventional rip-rap and an innovative rock mattress design. Stereo photography measurements quantify deformation and stability, while accelerometers monitor mattress motion during propeller-induced loading. To ensure accurate scaling, 3D printing is used for the mesh material of the bed protection. These scale-model tests offer insights into propeller jet-induced scour, enhancing bed protection strategies and bolstering the resilience and stability of quay walls and similar structures.