Parametrising wakes for oceanographic models

Project Description:

This PhD scholarship is offered by the EPSRC CDT in Offshore Wind Energy Sustainability and Resilience; a partnership between the Universities of Durham, Hull, Loughborough and Sheffield. The project is sponsored by industry partner, the Centre for Environment, Fisheries and Aquaculture Science (CEFAS). The successful applicant will undertake six-month of training with the rest of the CDT cohort at the University of Hull before continuing their PhD research at Loughborough University. The project is part of a Research Cluster focussing on Predicting Offshore Wind wake interactions for Energy and the enviRonment (POWER).

The offshore wind sector is rapidly expanding to meet net-zero energy demands. Individual turbines and farms are getting larger and further from shore, with individual turbines spanning 240 m in diameter and farms reaching 600 km2. Forced by spatial constraints, but enabled by floating technology, farms are now developing in deeper waters, occupying increasingly vast areas.

Oceanographic flow processes are highly sensitive to sea surface boundary conditions (Christiansen et al., 2022), which are in turn critically dependent on atmospheric forcing. Atmospheric flows past offshore wind turbines produce highly turbulent and extensive wakes. These wakes are a necessary result of energy extraction from the wind. They are a key motivation for spatial planning of offshore wind farms where turbine placement is optimised for maximal energy extraction with minimised costs associated to infrastructure and spatial footprint (Giebel et al., 2016). The turbulent wakes propagate downstream, leading to wake-wake interactions and farm-scale atmospheric flow processes with a significantly reduced wind speed in the lee of an offshore wind farm (Platis et al., 2018).

It has been recently shown that such large-scale atmospheric interactions can have a significant effect on sea-surface conditions, realised through a locally reduced wind shear stress (Christiansen et al., 2022). Large-scale deployment of offshore wind farms in shelf seas therefore poses an emerging oceanographic problem; shelf seas are vital for life on and below water through their control on the vertical transport of nutrients, and are a key component of the biogeochemical cycle (van Berkel et al., 2020). These are crucially dependent on general circulation and water column structure, which are both highly sensitive to conditions at the sea surface (Dorrell et al., 2022). Yet the impact of offshore wind expansion on sea surface conditions and subsequent regional scale effects is poorly understood and has only recently gained research interest. While wake parameterisations for atmospheric models have received significant interest over the last decade, the current state of the art oceanographic models make sweeping assumptions regarding the form of sea-surface forcing, particularly concerning wake-wake interactions, spatial variability, and turbulent modifications (Christiansen et al., 2022). These limitations must be overcome for accurate model predictions of oceanographic response to offshore wind expansion.

This project aims to advance sea-surface parameterisations of atmospheric offshore wind farm wakes for use in oceanographic models, directly supported by the National Oceanography Centre, using the North-West European Shelf FVCOM model. This aim will be realised through the following objectives:

• Explore literature and gather/generate datasets required for model validation
• Develop and validate wake parameterisations
• Explore the influence of solution sensitivity to model parameters
• Explore the potential impacts of future offshore wind development on North Sea oceanography

Completion of these objectives will deliver a functional oceanographic model for future research into impacts of offshore wind deployment to inform marine spatial planning.

Training & Skills

You will benefit from a taught programme, giving you a broad understanding of the breadth and depth of current and emerging offshore wind sector needs. This begins with an intensive six-month programme at the University of Hull for the new student intake, drawing on the expertise and facilities of all four academic partners. It is supplemented by Continuing Professional Development (CPD), which is embedded throughout your 4-year research scholarship.

You will undertake two three-week placements at NOC during the PhD programme to provide support with FVCOM. The first placement will occur at the start of year 2 where the basics of FVCOM will be taught. The second placement will occur at the start of year 3 to learn how to set up and validate FVCOM simulations, and implement parameterisations.  Beyond academia, this PhD project will open pathways to a career in physical oceanography, the wind energy sector, or more broadly a career using computational fluid dynamics or data science.

Entry requirements

If you have received a First-class Honours degree, or a 2:1 Honours degree and a Masters, or a Distinction at Masters level with any undergraduate degree (or the international equivalents) in engineering, environmental science, mathematics and statistics or physics, we would like to hear from you. The ideal candidate for this project will have studied fluid mechanics/physical oceanography to a high level as part of their undergraduate degree.

If your first language is not English, or you require Tier 4 student visa to study, you will be required to provide evidence of your English language proficiency level that meets the requirements of the CDT’s academic partners. This course requires academic IELTS 7.0 overall, with no less than 6.0 in each skill.

If you have any queries about this project, please contact Prof Rob Dorrell via auracdt@hull.ac.uk

Project Sponsor & Industry Supervision

In-kind support & Industry Supervision

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Funding

The CDT is funded by the EPSRC, allowing us to provide scholarships that cover fees plus a stipend set at the UKRI nationally agreed rates. These are currently circa £19,795 per annum at 2025/26 rates and will increase in line with the EPSRC guidelines for the subsequent years (subject to progress).

Eligibility

Research Council funding for postgraduate research has residence requirements. Our CDT scholarships are available to Home (UK) Students. To be considered a Home student, and therefore eligible for a full award, a student must have no restrictions on how long they can stay in the UK and have been ordinarily resident in the UK for at least 3 years prior to the start of the scholarship (with some further constraint regarding residence for education). For full eligibility information, please refer to the EPSRC website.

We also allocate a number of scholarships for International Students per cohort.

References

• van Berkel J., Burchard H., Christensen A., Mortensen L.O., Petersen O.S. and Thomsen F., 2020. The effects of offshore wind farms on hydrodynamics and implications for fishes. Oceanography 33(4), pp.108-117.
• Dorrell R.M., Lloyd C.J., Lincoln B.J., Rippeth T.P., Taylor J.R., Caulfield C.C.P., Sharples J., Polton J.A., Scannell B.D., Greaves D.M. and Hall R.A., 2022. Anthropogenic mixing in seasonally stratified shelf seas by offshore wind farm infrastructure. Frontiers in Marine Science (9), pp.830927.
• Platis, A., Siedersleben, S. K., Bange, J., Lampert, A., Bärfuss, K., Hankers, R., … & Emeis, S. (2018). First in situ evidence of wakes in the far field behind offshore wind farms. Scientific reports, 8(1), 2163
• Giebel, G., & Hasager, C. B. (2016). An overview of offshore wind farm design. MARE-WINT: New materials and reliability in offshore wind turbine technology, 337-346.
• Christiansen N., Daewel U., Djath B., Schrum C., 2022, Emergence of Large-Scale Hydrodynamic Structures Due to atmospheric Offshore Wind Farm Wakes, Frontiers in Marine Science (9)