Session: 07-04-01 Structures in Ice

Submission Number: 157494

A Co-Simulation Framework for Ice-Floating Wind Turbine Interaction 

With the growing demand for deploying floating offshore wind turbines (FOWTs) in ice-prone waters, this study presents a co-simulation framework for ice-FOWT interaction assessments. The framework integrates Abaqus and OrcaFlex for two-way coupled simulations, enabling detailed analyses of the complex interplay between ice mechanics and FOWT dynamics. Ice mechanical behaviour, including failure mechanisms, is modelled in Abaqus through a user-defined material model developed as a Fortran subroutine. This subroutine incorporates a nonlinear viscoelastic constitutive model with progressive damage evolution based on microstructural changes and phase transition in ice under compressive stress state. The flexural failure of ice is modelled using the cohesive zone method. The ice model has been validated against experimental data from physical indentation tests on conical ice samples and triaxial creep tests on cylindrical ice specimens. Additionally, the model has been applied to simulate concurrent flexural and crushing failures of level ice interacting with an ice-breaking cone of a jacket structure in the Bohai Sea, demonstrating good agreement with field measurements.

The FOWT system in OrcaFlex is modelled according to the NREL 5-MW baseline wind turbine installed on the OC3 Hywind spar floater. The turbine features a conventional three-bladed rotor, incorporating variable blade-pitch and variable-speed control, implemented via Python-scripted external functions. Aerodynamic loads are calculated using the blade element momentum (BEM) method. The spar platform is modelled as a six-degree-of-freedom rigid floating body and is anchored by a three-line catenary mooring system.

The FOWT responses under ice-free and level ice conditions are compared to provide insights into the influence of ice loads on system dynamics and internal loads. This co-simulation framework with a high-fidelity ice model may serve as a foundation for validating future numerical studies based on simplified ice models developed for enhanced computational efficiency.

Presenting Author: Mojtaba Mokhtari NTNU

Presenting Author Biography: Mojtaba Mokhtari is an Associate Professor at the Department of Marine Technology, Norwegian University of Science and Technology (NTNU). His research is centered on the multidisciplinary design, monitoring, and analysis of offshore renewable energy systems, using multiphysics and multiscale simulations, shape sensing, and smart materials.

He serves as an Associate Editor for the Journal of OMAE and is a member of the Materials and Fabrications Committee for the International Ship and Offshore Structures Congress (ISSC).

His accolades include the Onsager Fellowship, the Outstanding Academic Fellowship, the 2022 Moan-Faltinsen Best Paper Award, the 2018 Postgraduate Research Prize from the University of Newcastle, and recognition as a Global Talent by the Australian government.