Sea-Swallows Project Introduction
Initial experiments at the Danish Hydraulic Institute (DHI) in Denmark, led by Prof. Jun Zang, revealed the significance of nonlinear load contributions from violent wave impacts on offshore wind turbine foundations. This work identified a simple relationship between linear wave loading and higher-order nonlinear components, leading to a novel, efficient method for predicting the full complex nonlinear wave loading on monopiles (Chen et al., 2018).
The significance of higher-order wave loading on monopiles is clear in the figure below. As the wave steepness increases to 𝑘𝐴=0.3, the linear loading contributes to only 30% of the total peak loading (here with slenderness 𝑘R=0.19).
In the EPSRC funded Sea-Swallows project, "Severe Storm Wave Loads on Offshore Wind Turbine Foundations" (EP/V050079/1), we aim to establish a fast and accurate engineering model for predicting nonlinear wave loading on monopiles such as are typically used for fixed offshore wind turbine foundations. We create a ‘Stokes-type’ force model (Tang et al., 2024), relating the amplitude of each of the higher harmonics of force to the linear force time series raised to integer powers scaled by amplitude and phase coefficients.
• We re-analyse previous experimental data & perform new extensive physical and numerical experiments
• Establish a force coefficients database for engineering applications.
• Use new Stokes-Gaussian Process (Stokes-GP) Machine Learning model to interpolate coefficients.
• Provides confidence intervals for prediction uncertainty and reflects model reliability.
• Fast to compute, and all the important higher-order load components are included.
• Improves the accuracy of wave load prediction for the design of monopile foundations.
