Risk and uncertainties in prediction of scour around offshore wind farm foundations
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This is a project within the multi-disciplinary EPSRC and ESRC Centre for Doctoral Training (CDT) on Quantification and Management of Risk & Uncertainty in Complex Systems & Environments, within the Institute for Risk and Uncertainty. The studentship is granted for 4 years and includes, in the first year, a Master in Decision Making under Risk & Uncertainty. The project includes extensive collaboration with prime industry to build an optimal basis for employability.
There has been a rapid growth in offshore wind energy in recent years in European waters. The European Wind Energy Association 2013 report estimates an eight times increase in capacity by the end of 2020.
A range of different foundation designs for wind turbine generators have been proposed in recent years to reduce costs and develop more efficient structures. To date, monopile foundations dominate built or currently planned wind farms. Dependent on site conditions scour protection measures may be required around the foundation to prevent or significantly reduce structural failure. However, there is a lack of numerical tools capable to design such protections. The existing understanding of complex flow-structure-seabed interactions is still very limited, and leads to large uncertainties in predicting scour process around foundations, including effects of secondary/edge scour around the armouring layer (Whitehouse et al., 2011).
More recently, a modelling study based on detailed CFD simulation of sand-flow-structure interactions has shown the potential in predicting scour initiation and development around horizontal pipelines and vertical monopiles with uniform sand size (Li et al., 2015). Extending the code to operate with a mixture of rock and sand particles of very different sizes, would enable the approach to be applied to assessing the performance of scour protection placed on a granular seabed. Development of such a tool through the extension of the modelling approach would provide a unique model that could be used to improve the design of scour countermeasures with relevance for offshore renewables and oil and gas developments and could potentially produce a step-change in scour protection design.
This project focuses on detailed modelling of flow-sediment-structure interactions around offshore structures, and wind farm foundations with emphasis on scour protection measures. This project aims to assess risk and uncertainties associated with scour development at offshore foundations through the development of new methods for modelling hydrodynamics and sediment transport around the foundation including the presence of scour protection; quantify uncertainties in scour development around protections; and quantify the risk level based on typical offshore wave-current conditions around designated UK offshore wind farm sites. The project will develop a new method to simulate the flow and sediment transport around a vertical cylinder using a particle based approach. Scour protection will be represented through larger elements with different behavioural characteristics to those of the background granular seabed sediment. Available laboratory data will be analysed to identify the key processes that influence the scour and will be used to calibrate and validate the model’s prediction. Published and unpublished data on morphological and process changes around existing offshore wind farm sites will be used to validate hydrodynamic modules and scour predictions. The model will be driven by typical offshore wave-current conditions for offshore wind farm sites in European waters including a number of different scour protection solutions. By testing different situations, the modelling will be able to identify the effects of these protection structures on the scour development process. The predictability and uncertainty in the model outputs will be assessed. The effects of different degrees of alteration on erosion and sediment flux, scouring and structure instability will be modelled as will the effectiveness of the protection methods.
The project will involve placements for up to 6 months with the partner, HR Wallingford. Applicants should have a background in Mathematics, Engineering (preferably Civil or Environmental) and Environmental Sciences (Oceanography, Geology or Environmental Sciences). The project requires a strong numerical background and a keen interest to work at the interface of engineering, environmental, modelling and oceanographic scientists. To be eligible for funding, you must either be a U.K. citizen or a European Union national. The project, as well developing skills applicable in an academic setting, will deliver excellent training in the knowledge required to work in a wide variety of environmentally-facing careers, including those with the EA, Natural England or DEFRA, as well as Environmental and Civil Engineering Consultancies.
The PhD Studentship (Tuition fees + stipend of £ 13,726 annually over 4 years) is available for Home/EU students. In addition, a budget for use in own responsibility will be provided.