Multiphysics analysis of a flexible oscillating water column wave energy converter with dielectric elastomer membrane

• A multiphysics framework was developed for flexible wave energy converter analysis. • Electric field activation reduces membrane stiffness and alters deformation modes. • Voltage-induced stress increase is highest at membrane centre and edge regions. • Output power grows quadratically with increasing initial voltage. • The proposed model offers insights for energy harvesting and design optimization. Flexible wave energy converters (FlexWECs) have emerged as a promising solution to address the limitations of conventional rigid devices in harsh marine environments. Among them, oscillating water column (OWC) systems integrated with dielectric elastomer generators (DEGs) offer simplified architectures, enhanced adaptability, and direct wave-to-electric energy conversion. However, the complex multiphysics interactions between fluid, structure, and electric fields remain poorly understood, hindering design optimization and performance prediction. This study develops a high-fidelity computational framework to simulate the coupled fluid-structure-electric behaviour of a flexible OWC wave energy converter (WEC) with a DEG membrane. The framework is first validated against experimental data, demonstrating good agreement in capturing the deformation of the flexible membrane induced by the coupled electrostatic and hydrodynamic forces. Subsequently, the model is applied to investigate how electric field influences the WEC system behaviour under regular wave excitation. Results show that applying an electric field reduces the effective stiffness of the membrane, leading to increased deformation. Additionally, it does raise overall structural stress levels, especially near the membrane centre and edge regions, where the maximum stresses are observed. Notably, electric excitation induces a secondary deformation mode in the membrane during the near-flat phase. These effects become more pronounced with increasing initial voltage, which also leads to an approximately quadratic increase in output power. The insights gained from this study provide a deeper understanding of fluid-structure-electricity (FSE) interactions in flexible OWC WECs and offer design guidance for enhancing energy harvesting efficiency in next-generation WEC devices.