Numerical simulations of towing a jacket foundation with triple buckets

Abstract

Abstract Offshore wind energy is developing fast as a promising renewable energy resource that can be helpful in achieving the global net-zero emissions goal. In recent years, offshore wind turbine projects have gradually moved towards far-offshore sea areas, where massive jacket foundations with suction buckets are suitable options. To reduce transportation costs, the wet-towing method is usually favourable since the required buoyancy of the foundation can be provided by the air cushions in the suction buckets. This engineering background brings us a research topic that involves towing and air cushions in waves. This study considers the towing problem of a jacket foundation with triple suction buckets. First, numerical analysis in the frequency domain is conducted using WAMIT®. In particular, the NEWMODES subroutine is extended to consider three separate motion modes in the buckets. Numerical predictions of the natural period show satisfactory agreement with the available experimental data in the literature. Moreover, a time-domain numerical model is developed to simulate towing of the jacket foundation in regular waves based on the potential flow theory. The time-domain model numerically solves the towing force in regular waves, the body motions and the air pressures in the buckets. The simulation results generally agree well with the published experimental data. Besides, the present simulation results suggest that the transit towing force and the forward speed of towed triple-bucket jacket may be considerable in the initial towing stage.