Flexcom: Simulation software evolving in harmony with the offshore energy industry

The advancement of offshore field developments to deeper waters and more challenging environments, coupled with increasingly stringent safety requirements, has led to the need for high quality software to support the engineering design process.

With nearly 40 years of global experience, Wood’s proprietary software, Flexcom, is a simulator for dynamic offshore structures and has provided advanced engineering solutions to major operators, EPC contractors, equipment suppliers and engineering consulting companies. This comprehensive software is suitable for a variety of scenarios, ranging from FEED studies, detailed engineering design, fatigue life assessment, structural installation and decommissioning. It is highly versatile and easily lends itself to applications in growing sectors such as marine renewables and floating offshore wind.

The name Flexcom derives from its origins as comsimulation software flexible risers, suitable for emerging North Sea oil production technology in the early 1980s. In contrast, the most recent edition has been developed to focus on floating offshore wind. The Tool Evolution is a classic example of an innovative solutions provider adapting to ever-changing industry requirements. From humble beginnings with a single customer in 1983, Flexcom now has over 300 users worldwide.

So what makes Flexcom unique? Basically, Flexcom is a Finite Element Analysis (FEA) tool that uses an industry-proven finite element formulation widely recognized as best in class. Offshore structures experience significant motion when subjected to ocean waves. Therefore, unlike some other FEA solvers, Flexcom uses a convected coordinate technique to respond to large-scale displacements. Each element of the finite element discretization is associated with a local axis system, which realigns with the element as it moves in space and time. This allows small elastic deformations inducing stresses from large rigid body motions to be accurately identified. This technique makes Flexcom particularly well suited to modeling structures that have large movements, such as the highly dynamic inter-array cables between floating offshore wind turbines.

Given the growing importance of offshore wind in the decarbonization strategy of many countries, and in particular the predicted exponential future growth of floating wind, the need for validated numerical modeling tools to support engineering design detail is now more important than ever. Wood established an independent technical advisory group in 2016, alongside some key players in floating offshore wind, which helped shape a new product known as Flexcom Wind. This tool provides state-of-the-art aerodynamic modeling delivered through a fully integrated coupling with industry-recognized OpenFAST software, while detailed structural analysis of underwater components, such as mooring lines and dynamic cables, is provided by Flexcom itself.

Wood has won several contracts for floating wind projects, supported by Flexcom Wind. An example was for a wind farm project located off the west coast of Ireland, an ambitious project targeting up to 1.35 GW of wind energy. In concrete terms, this wind farm has the potential to power up to 1,145,000 homes by harnessing the power of the North Atlantic wind. However, this location represents a harsh environment with severe sea states and high winds, which poses significant challenges for the design of dynamic mooring systems and power cables, including long-term fatigue performance and cable integrity. A truss element has recently been introduced in Flexcom, specifically designed to model structures with low structural bending stiffness, such as mooring chains. The new functionality provides a very efficient solution, with faster calculation times compared to a traditional beam element.

The continuous development of technologies and solutions to meet changing industry requirements is a key focus area for Wood. A typical 1 GW floating offshore wind farm will have over 120 dynamic cables, and the sheer volume of cables required for floating wind provides a unique opportunity to use digital twin and machine learning technologies to aid in management of integrity.

Wood is actively developing an “undersea cable digital twin”. This digital twin takes into account both mechanical fatigue and electrically induced thermal damage, the former being based on near real-time FEA, where Flexcom is expected to play a key role. This will accompany Flexcom’s sister product, Layercom, a simulation tool that provides additional fatigue information at a localized section level, including armor wires and cable strands in dynamic cable. The benefit of a digital twin approach is that an integrated and maintained picture of cable condition can be developed, giving the owner confidence in integrity and real-time performance. The approach has been well validated by cable thermal monitoring and cable fatigue damage assessments for many operational cable assets in the North Sea. Wood’s long-term vision is to provide specialized software that meets current and future industry requirements, where large-scale deployments of floating wind turbines become a commercial reality.

Originally published in Global Underwater Hub Magazine (page 14)

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