An integrated hydrodynamic module of FOWTs using accelerated BEM solver and modified Morison coefficients

Abstract

Hydrodynamics is critical to the stability and safety of floating offshore wind turbines (FOWTs). To improve computational efficiency in the preliminary design stage, frequency-to-time domain potential flow method combined with the Morison equation are commonly used. However, this method lack systematic validation and require multiple tools, leading to complex workflows and inefficient data transfer. To address these challenges, an integrated hydrodynamic module named Zwave is presented in this study, aiming to streamline wave generation, meshing, potential flow analysis, and viscous force calculation. It incorporates advanced features such as parameterized meshing, an accelerated boundary element solver, and amplitude- and frequency-dependent Morison coefficients. Component-level verification shows that Zwave accurately reproduces target wave spectra, and its hydrodynamic results align well with WAMIT in the frequency domain and Orcaflex in the time domain. Furthermore, with corrected Morison coefficients, Zwave successfully captures the resonance responses observed in wave basin tests. Building upon this, system-level validation is performed using field measurements from the Fukushima 2 MW FOWT, demonstrating good agreement in tower base and top bending moments under various sea states.