The Influence of Wave Diffraction on the Motion of a Crew Transfer Vessel Behind a Monopile

authored by: Jannik Meyer, Thilo Grotebrune, Mareile Wynants, Arndt Hildebrandt, Torsten Schlurmann
Abstract: In this experimental study, the incidence of wave diffraction behind monopile foundations and their influence on the motion response of a CTV are investigated. The model tests were conducted in the wave flume Schneiderberg (German: Wellenkanal Schneiderberg, WKS) in a scale of 1/40. The water depth was fixed to 40 m (all following quantities are given in prototype scale). Four sets of tests were conducted: (i) Wave-only tests without vessel or monopile to measure the undisturbed wave, (ii) Vessel-only tests without monopile to measure the reference motion response of the vessel, (iii) monopile-only tests without the vessel to measure the wave field behind the monopile, which will subsequently cause the motion response of the vessel behind the monopile. This is investigated in test set (iv): monopile-vessel tests to measure the motion response of the vessel behind the monopile. Monopiles with different diameters D of 6.4 m, 8 m and 10 m were tested, while the distance between vessel bow and monopile had three fixed values of 10 m, 18 m and 40 m as well. Regular waves with wave periods T between 5 s and 10 s were generated, while the wave height H was set to 1 m, 2 m, and 3 m. The results show that the expected diffraction effects occur behind the monopiles, especially for short period waves and large diameter monopiles, leading to a large diffraction parameter ka. These diffraction effects have a significant influence on the vessel’s motion response. However, further analyses indicate that other hydrodynamic interactions (e.g., vessel’s radiated wave interacts with monopile’s diffracted wave) are important for an accurate prediction of vessel motion during CTV-based maintenance operations. The incorporation of these hydromechanic coupling effects in planning tools as well as real-time systems could lead to an significant increase in technician safety as well as maintenance efficiency.
Organisation(s): Ludwig-Franzius-Institute of Hydraulics, Estuarine and Coastal Engineering
CRC 1463: Integrated Design and Operation Methodology for Offshore Megastructures
Type: Conference contribution
Volume: 5A
No. of pages: 8
Publication date: 2024
Publication status: Published
Peer reviewed: Yes
ASJC Scopus subject areas: Ocean Engineering, Energy Engineering and Power Technology, Mechanical Engineering
Sustainable Development Goals: SDG 7 - Affordable and Clean Energy, SDG 13 - Climate Action
Electronic version(s): https://doi.org/10.1115/omae2024-123620 (Access: Closed)