UWA Researchers Develop Model to Predict Green Water Loading on FPSOs

Researchers at The University of Western Australia have developed a novel model to accurately predict green water loading, where water washes onto an offshore facility's deck during extreme waves. Developed for floating production, storage and offloading facilities, the model draws on Newton's 300-year-old conservation of momentum principles applied to hydrodynamics for the first time. The breakthrough enables faster, more precise estimates of green water loads, supporting the design of safer and more cost-effective offshore facilities.

 

Understanding Green Water Loading

 

The research addresses a specific offshore hazard. Green water refers to water washing onto a facility's deck. This occurs during extreme wave conditions at sea. It can impact equipment and structures on the deck. Predicting these forces is essential for safe design.

The phenomenon poses particular challenges for FPSO facilities. These facilities house essential hydrocarbon processing components. These include separation systems and gas compression equipment. Power generation, control rooms and living spaces are also present. Protecting this equipment from green water is a key design concern.

 

The Research Approach

 

The research was conducted through physical and computational testing. Researchers used the university's wave flume for the work. They deployed scale models of an FPSO and its topside modules. These recreated extreme wave events under controlled conditions. This allowed them to measure how water overtops the vessel.

The testing generated detailed data on green water forces. The experiments measured how water impacts the deck structures. This identified the largest green water forces that occur. Advanced computational fluid dynamics complemented the physical tests. Together these investigated loading on different shaped structures.

 

The Newtonian Breakthrough

 

The key advance came from an unexpected source. A researcher found a simpler method based on Newton's principles. This drew on conservation of momentum principles. The method can accurately predict forces from shallow, high-speed flows. Green water overtopping is exactly such a flow.

The application of this theory was historically novel. Newtonian momentum theory was written more than 300 years ago. It had proven useful in hypersonic aerodynamics. However, it had not been successfully applied to hydrodynamics. This research marked its first successful application in this field.

 

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Practical Benefits for Design

 

The model offers significant practical advantages. It enables accurate estimation of loads on topside structures. This requires only information on the undisturbed on-deck flow. The estimate holds regardless of where components are placed. This flexibility makes the model widely applicable.

These capabilities support better offshore design. The model allows faster and easier estimates of green water loads. Industry partners can iterate and optimise hull size and layouts. Previous analytical methods were only approximate. The new method is more precise, supporting safer and more cost-effective facilities.

 

Significance and Wider Applications

 

The research directly addresses industry design challenges. Partners wanted to optimise hull size without compromising safety. Reducing hull size must not reduce structural reliability. The research materially improved understanding of green water loading. This understanding can now be explored for inclusion in industry standards.

The applications extend beyond offshore facilities. The research has potential benefits for coastal structures. It could help understand damage during tropical storms. This broadens the relevance of the findings considerably. The close industry-research relationship was credited with enabling these outcomes.