Renewable Energy, Sustainability and the Environment, Mechanical Engineering
139
Scopus Publications
Scopus Publications
Dispersive Wave Focusing in Shoaling Water With Currents Y. Watanabe, T. Davey, D. M. Ingram Journal of Geophysical Research Oceans, 2026 A methodology creating dispersive focusing waves on constant depth, originally proposed by Rapp and Melville (1990), https://doi.org/10.1098/rsta.1990.0098 , has provided a wide range of applications studying nonlinear waves, wave breaking, and rogue waves in the open ocean. When the wave focusing is considered in coastal regions, generally having depth variations and coastal currents, effects of shoaling on beaches and interactions with currents must be included for predicting wave growth. Here we present the general form of a chirp frequency achieving complete wave‐energy focusing in arbitrary depth variations and currents. The proposed method has been validated through wave experiments in a wave flume with sloped beach and opposing currents. It was found that the current velocity significantly contributes to wave growth, achieving a maximum crest height 6.1 times higher than the incident wave in the strongest current considered. The dual effects of shoaling and radiation stress, intensified by the opposing current, contribute to the rapid growth of the wave energy density near the focusing point. Nonlinearity develops once waves are highly amplified, causing spectrum energy spread from the primary frequency band to wider frequencies depending on the current velocity. Whereas the nonlinear energy spread disappears after focusing when divergent waves travel in constant depth, the effects of shoaling and radiation stress maintain the nonlinear features of the waves behind the focus location on a beach. The proposed method achieving dispersive focusing will help in further understanding of nonlinear behaviors of breathers and wave breaking in arbitrary current and coastal geometry.
Redefining fatigue predictions: A multi-sea state HPC framework for FOWTs Prokopios Vlachogiannis, Christophe Peyrard, Ajit C. Pillai, David Ingram, Pierre Bousseau, Maurizio Collu Ocean Engineering, 2025 Offshore wind is essential in the global transition to Net Zero carbon emission goals. As the industry pushes into deeper waters, fixed offshore wind solutions are no longer viable, increasing the reliance on floating alternatives. During their operational lifespan of at least 25 years, floating wind turbines are exposed to stochastic winds, waves, currents and the non-linear coupled loads, making fatigue assessment critical in their design and maintenance planning. The industry standard approach is to group similar conditions together into bins, each with a corresponding probability of occurrence based on historical data. However, by assuming all bin members are equivalent, this binning approach results in a loss of information, leading to inaccuracies. Here we propose a more detailed approach, called Numerical Prototype approach, where every individual sea state is considered, produces in turn fatigue estimates expected to be closer to reality since less information is lost due to binning. This paper studies the UMaine VolturnUS-S semi-submersible platform with the IEA 15 MW turbine for with a modified tower for an Atlantic site on the west of France. For the turbine tower, the Numerical Prototype results indicate lower cumulative fatigue estimations by 24 % for the principal direction of fatigue than those calculated using the classical binning method, while for the mooring line fairleads fatigue estimations are up to 14 % lower. These findings suggest that a more discretised calculation and more detailed representation of met-ocean loads lead to lower fatigue predictions, revealing the conservative nature of existing industrial methods. The binning methods currently used in industry result in conservative designs with increased material use and increased costs of floating wind turbines. The present results indicate for the first time a detailed methodology for fatigue estimation that allows optimised designs to reduce structural weight with consequent savings in both installation and material costs. Although the proposed methodology is computationally expensive, the potential savings offer significant benefits for project developers.
OPTIMIZING FATIGUE LIFE PREDICTIONS FOR FLOATING OFFSHORE WIND TURBINES: IMPACT OF BINNING AND DATA DURATION Prokopios Vlachogiannis, Christophe Peyrard, Ajit C. Pillai, David Ingram, Maurizio Collu Proceedings of the International Conference on Offshore Mechanics and Arctic Engineering OMAE, 2025 Floating Offshore Wind Turbines (FOWTs) experience dynamic environmental loads over their lifetime, making accurate fatigue assessment crucial for structural reliability and optimised design. Binning methods simplify metocean conditions by grouping environmental inputs into representative cases, reducing computational complexity. However, uncertainties arise from bin size and the length of input data, particularly in long-term fatigue predictions. This study investigates the impact of binning strategies on fatigue life predictions over a 25-year design life, focusing on the effect of metocean input data duration. Using 30 years of the ANEMOC3 hindcast as reference, subsets of 5-, 10- and 15-year data were analyzed. Fatigue damage at key components, such as the tower base and mooring line fairleads of the VolturnUS/IEA 15MW semi-submersible, was calculated. Results show that with 15 years of data, relative errors in tower base fatigue predictions remain below 6%, while heavily loaded mooring lines exhibit errors under 3%. Even with 10 years of data, tower base errors stay within 10%, and mooring line errors below 4%. For the first time, these findings demonstrate that accurate fatigue predictions are achievable without extensive datasets, enabling faster project development in data-scarce regions. This study supports cost reductions and accelerates offshore wind expansion to meet net-zero targets.
[FREEFORM-ADCP] An open toolbox for the design and operation of arbitrary geometry mono-static ultrasonic velocity profiling systems Marilou Jourdain de Thieulloy, Brian G. Sellar, David M. Ingram Softwarex, 2024 FREEFORM-ADCP is a MATLAB-based toolbox developed to support the design and operation of mono-static ultrasonic velocity profiling systems of arbitrary geometry. The toolbox enables: (1) Acoustic beam orientation definition and internal transducer parameter tuning as function of a target focal point , (2) Acoustic beam and bin mapping, and (3) Transformation of multi-beam velocities to 3D velocity. This toolbox applies to mono-static ultrasonic profiling systems (which measure velocity via the acoustic Doppler technique) of arbitrary geometry, with parameters such as the number of transducers, transducer location, orientation, and geometrically convergent or divergent configuration. Thanks to its universality, this toolbox applies to the use of standard diverging-beam Acoustic Doppler Current Profilers (D-ADCPs), stand-alone or distributed, along with novel systems including converging-beam ADCPs (C-ADCPs), fixed or actuated. This toolbox has been used to advance the design and operation of novel sensor techniques for flow characterisation, and is intended to support further development.
Sensitivity of turbulence parameters to tidal energy converter loads in BEM simulations Alyona Naberezhnykh, David Ingram, Ian Ashton, Calum Miller Journal of Ocean Engineering and Marine Energy, 2024 Renewable energy is playing an increasingly central role in the global energy supply due to decarbonisation and energy security aims. A vital aspect of renewable energy systems will be the predictability of the energy source, something that tidal stream energy can provide. The tidal sites suitable for energy extraction are by their nature turbulent, creating variations in the tidal energy converter (TEC) loads and affecting device durability. Developers use Blade Element Momentum (BEM) models to predict loading and improve designs of TECs. To simulate turbulence effects within these models, a synthetic flow field is generated using a combination of measured and assumed parameters. Inaccuracies in these parameters can lead to uncertainties in the simulated loads. This study investigates the sensitivity of turbulence characteristics to loads using a commercial BEM software. Variability in parameters shows a profound impact on the loads. Varying turbulence intensity resulted in a $$90\\%$$ 90 % change in fatigue loads for intensities ranging 2–24%. Length-scales showed a $$49\\%$$ 49 % decrease in loads across the range tested (5–70 m). A coherent flow field increased loads by $$45\\%$$ 45 % compared to a non-coherent flow. Hub-bending loads varied by $$30\\%$$ 30 % between different shear profiles, however varying the standard deviation profiles did not show notable effects. The results from this study emphasise the necessity for accurate turbulence parameter inputs to reduce uncertainty in device load modelling. It also highlights the importance of using realistic shear profiles as well as appropriate coherence models.
Implications of wave–current interaction on the dynamic responses of a floating offshore wind turbine Mujahid Elobeid, Ajit C. Pillai, Longbin Tao, David Ingram, Jan Erik Hanssen, Pedro Mayorga Ocean Engineering, 2024 This study investigates the implications of wave–current interaction on the dynamic responses of the W2Power semisubmersible platform for floating offshore wind turbines under operational and extreme conditions. Firstly, two analytical models based on Airy wave theory are developed to analyse the effects of current interaction with regular and irregular waves. Then, these models are integrated with the well-known engineering tool OrcaFlex for the coupled aero-hydro-servo-elastic analysis. The presence of current was found to significantly modify the wave profiles and influence the static equilibrium, mooring system, and motion dynamics of the FOWT. The results reveal that the translational motion responses, such as surge and heave, are affected by wave–current interaction, with mean and maximum values decreasing under a following current and increasing under an opposing current. However, rotational motion responses are minimally affected. Wave–current interaction also notably affects maximum mooring tensions, with variations of up to ±22% depending on the current direction and mooring layout. Furthermore, reductions in maximum longitudinal acceleration are observed due to such interaction. Incorporating wave–current interaction in simulations enhances our understanding of FOWT dynamics and allows for more reliable estimations of system behaviour, emphasising the importance of ensuring safe operating conditions, particularly in sites with opposing currents.
Floating offshore wind – an overview of marine spatial planning and the needs of the industry O Dvorak, G Bohan, A Incecik, D Ingram, I Ashton, D Konovessis Journal of Physics Conference Series, 2024 The International Energy Agency (IEA) Wind Task 49 aims to accelerate the commercialisation of floating wind. Work package 4 of the task analyses and incorporates the views of key stakeholders to ensure the Task is aligned with industrial needs. Work package 4 is broadly split into innovation management and marine spatial planning (MSP). The innovation management section evaluates the potential social, environmental and economic impact of floating wind innovations by surveying a multidisciplinary group of stakeholders to ask them to compare the potential impact of identified innovations. The survey results will inform a scored ranking of floating wind innovations, and the future research directions for the Task. In the MSP section representatives from partner countries are interviewed to assess their domestic offshore wind sector and discuss the approach the country has taken to MSP, with a focus on floating wind. The other explored parameters include MSP regulations, offshore wind policy and targets, supply chain capabilities, and environmental and fisheries impact assessments. A synthesis of what stakeholders perceive as impactful innovation, and an understanding of the direction of the industry and policy can be built from the two parts. This paper describes the methodology used to create this synthesis and findings from the first year of work are shared.
Wavelet applications for turbulence characterisation of real tidal flows measured with an ADCP Alyona Naberezhnykh, David Ingram, Ian Ashton Ocean Engineering, 2023 Understanding turbulence is crucial to the design of tidal energy converters as it influences loads, fatigue life and power production. Acoustic Doppler Current Profilers (ADCPs) are normally employed in measurement campaigns to analyse turbulence at a particular location. Coherent turbulent structures are known to lead to the highest turbulence-induced stresses and are typically analysed by Fourier transform. However, this method can only yield parameters which are averaged over the signal length or the analysing window, and hence may not fully represent real flow turbulence, which is often non-stationary. This study applies wavelet time–frequency analysis to ADCP data from an active tidal test site to examine the turbulence spectrum and coherence characteristics of the flow, comparing these to Fourier methods. Results show that the average quantities from wavelet analysis agree favourably with Fourier analysis. Moreover, wavelet analysis yields instantaneous spectra and coherence, which show that at this site, high energy bursts occur at frequencies known to be significant for TEC loading and have turbulence intensities up to 80% higher than the average. We show that these intermittent, coherent bursts are obscured by the averages associated with Fourier analysis, highlighting the need for methods such as wavelets to understand interactions between fluid flow and TEC.
Hydrodynamic loads on a restrained ROV under waves and current Roman Gabl, Thomas Davey, Yu Cao, Qian Li, Boyang Li, Kyle L. Walker, Francesco Giorgio-Serchi, Simona Aracri, Aristides Kiprakis, Adam A. Stokes, David M. Ingram Ocean Engineering, 2021
Experimental measurement of the loads on tidal turbines using conditions derived from field measurements Proceedings of the European Wave and Tidal Energy Conference, 2021
Constructive and destructive interference locations of waves in a circular wave basin-study of velocity component perpendicular to wave direction- Proceedings of the International Offshore and Polar Engineering Conference, 2021
Torque control of a laboratory scale variable speed hydrokinetic tidal turbine: Cfd simulation and validation Proceedings of the International Conference on Offshore Mechanics and Arctic Engineering OMAE, 2020
Numerical recreation of the draupner wave in crossing wave systems using smoothed particle hydrodynamics Proceedings of the International Conference on Offshore Mechanics and Arctic Engineering OMAE, 2020
Applying site-specific resource assessment: Emulation of representative EMEC seas in the FloWave facility Proceedings of the International Offshore and Polar Engineering Conference, 2015
Vertical mixing layer development Adam Robinson, Jean-Baptiste Richon, Ian Bryden, Tom Bruce, David Ingram European Journal of Mechanics B Fluids, 2014
The all-waters test facility - The role of a new facility in physical modelling for marine and coastal engineering Coasts Marine Structures and Breakwaters 2013 from Sea to Shore Meeting the Challenges of the Sea, 2014
Discussion on paper B5.2 (Patterson): Author's reply Coasts Marine Structures and Breakwaters Adapting to Change Proceedings of the 9th International Conference, 2010
Wave Interaction with a Sea Dike Using a VOF Finite-Volume Method Proceedings of the International Offshore and Polar Engineering Conference, 2003
Numerical and experimental predictions of overtopping volumes for violent overtopping events Coastal Structures 2003 Proceedings of the Conference, 2003
On the validity of the shallow water equations for violent wave overtopping Proceedings of the International Symposium on Ocean Wave Measurement and Analysis, 2001
Numerically simulating seawall overtopping Coastal Engineering 2000 Proceedings of the 27th International Conference on Coastal Engineering Icce 2000, 2000
A comparison of high resolution schemes for transcritical shallow water flow Coastal Engineering and Marina Developments Proceedings of the 4th International Conference on Computer Modelling of Seas and Coastal Regions Lemnos May 1999, 1999
Numerical modelling of impulsive wave over-topping of coastal structures Coastal Engineering and Marina Developments Proceedings of the 4th International Conference on Computer Modelling of Seas and Coastal Regions Lemnos May 1999, 1999
