Wave energy convertors (WECs) offer opportunities for niche (powering aquaculture and offshore stations) and grid-scale applications. However, disruptive innovation is essential to unlock the potential of wave energy, achieve step change reduction in cost of energy, and prove competitiveness against other renewable energy options. Here we investigate the opportunity to transform the development of WEC systems by utilising intelligent design concepts that exploit novel use of deformable materials. WECs based on deformable materials may offer improved performance, survivability, reliability, and reduced cost compared with steel or concrete alternatives for the following reasons: 1. To achieve a given resonant frequency, a flexible fabric device can be smaller and lighter. 2. Hydrodynamic characteristics of such a device can be modified by controlling its internal fluid pressure, enabling it to be tuned to suit incident wave conditions. These adjustments can be made by an on-board intelligent responsive system. 3. Controlled non-linear changes of geometry would enable a deformable fabric structure to accommodate or shed high loads without reaching critical stress concentrations, improving survivability and reducing installation and lifetime costs. 4. Flexibility opens up the possibility to use a range of PTOs, such as novel distributed embedded energy converters (DEECs) utilising distributed bellows action, electro active polymers, electric double layer capacitors or micro-hydraulic displacement machines. 5. A lightweight flexible structure with largely elastic polymer construction is unlikely to cause collision damage, and so is therefore a low risk option for niche applications, such as co-location with offshore wind devices. The performance of flexible responsive systems in wave energy, their optimisation in operating conditions, and their ability to survive storm waves, will be assessed through a programme of wave basin experiments and numerical modelling of different flexible WEC concepts. Survivability is a critical hurdle for all WEC concepts as by their nature they need to respond in energetic sea states while avoiding critical stresses in extreme seas. For a flexible responsive structure, this means avoiding concentration of stress (naturally avoided by collapse/folding) or of strain (avoided by use of a distributed PTO during operational conditions). Numerical models will be developed that account for complex interactions between wave action, deforming membrane structure, and internal fluid. The models will be informed, calibrated, and validated using results from materials testing and fundamental hydro-elastic experiments. Advantages and disadvantages of rubber-based, polyurethane and other reinforced polymer materials will be assessed in terms of manufacturing cost, join, bonding, and fatigue performance in the marine environment. The research will draw on origami theory and the technology of deployable structures to avoid problems with wrinkling, folding, or aneurysm formation, and an entirely new design may emerge through this innovative approach. We aim to demonstrate a pathway to cost reduction for flexible fabric WECs optimising for performance, structural design and manufacture for both utility scale and niche applications.

The proposed new CCP-WSI+ builds on the impact generated by the Collaborative Computational Project in Wave Structure Interaction (CCP-WSI) and extends it to connect together previously separate communities in computational fluid dynamics (CFD) and computational structural mechanics (CSM). The new CCP-WSI+ collaboration builds on the NWT, will accelerate the development of Fully Coupled Wave Structure Interaction (FCWSI) modelling suitable for dealing with the latest challenges in offshore and coastal engineering. Since being established in 2015, CCP-WSI has provided strategic leadership for the WSI community, and has been successful in generating impact in: Strategy setting, Contributions to knowledge, and Strategic software development and support. The existing CCP-WSI network has identified priorities for WSI code development through industry focus group workshops; it has advanced understanding of the applicability and reliability of WSI through an internationally recognised Blind Test series; and supported collaborative code development. Acceleration of the offshore renewable energy sector and protection of coastal communities are strategic priorities for the UK and involve complex WSI challenges. Designers need computational tools that can deal with complex environmental load conditions and complex structures with confidence in their reliability and appropriate use. Computational tools are essential for design and assessment within these priority areas and there is a need for continued support of their development, appropriate utilisation and implementation to take advantage of recent advances in HPC architecture. Both the CFD and CSM communities have similar challenges in needing computationally efficient code development suitable for simulations of design cases of greater and greater complexity and scale. Many different codes are available commercially and are developed in academia, but there remains considerable uncertainty in the reliability of their use in different applications and of independent qualitative measures of the quality of a simulation. One of the novelties of this CCP is that in addition to considering the interface between fluids and structures from a computational perspective, we propose to bring together the two UK expert communities who are leading developments in those respective fields. The motivation is to develop FCWSI software, which couples the best in class CFD tools with the most recent innovations in computational solid mechanics. Due to the complexity of both fields, this would not be achievable without interdisciplinary collaboration and co-design of FCWSI software. The CCP-WSI+ will bring the CFD and CSM communities together through a series of networking events and industry workshops designed to share good practice and exchange advances across disciplines and to develop the roadmap for the next generation of FCWSI tools. Training and workshops will support the co-creation of code coupling methodologies and libraries to support the range of CFD codes used in an open source environment for community use and to aid parallel implementation. The CCP-WSI+ will carry out a software audit on WSI codes and the data repository and website will be extended and enhanced with database visualisation and archiving to allow for contributions from the expanded community. Code developments will be supported through provision and management of the code repository, user support and training in software engineering and best practice for coupling and parallelisation. By bringing together two communities of researchers who are independently investigating new computational methods for fluids and structures, we believe we will be able to co-design the next generation of FCWSI tools with realism both in the flow physics and the structural response, and in this way, will unlock new complex applications in ocean and coastal engineering