Ian Masters

• PhD
• Professor at Swansea University

The presence of Tidal Stream Turbines (TST) for tidal power production, leads to changes in the local physical environment that could affect fish. While other work has considered the implications with respect to conventional hydroelectric devices (i.e. hydroelectric dams), including studies such as physical impact with the rotors and pressure varia...

Wave energy resources are intermittent and variable over both spatial and temporal scales. This is of concern when considering the supply of power to the electricity grid. This paper investigates whether deploying arrays of devices across multiple spatially separated sites can reduce intermittency of supply and step changes in generated power, ther...

Efficient numerical simulation of renewable energy wind and tidal turbines is important for the layout of devices in farms. Computational Fluid Dynamics (CFD) approaches using blade geometry resolved models are computationally expensive. Therefore, most array models use source term representations of rotors, normally actuator disk, actuator line or...

Tidal energy is one of promising solutions for reducing greenhouse gas emissions and it is estimated that 100 TWh of electricity could be produced every year from suitable sites around the world. Although premature gearbox failures have plagued the wind turbine industry, and considerable research efforts continue to address this challenge, tidal tu...

Simulating fully resolved Horizontal Axis Tidal Turbine (HATT) geometry for a time period great enough to resolve a fully developed wake, and accurately predict power and thrust characteristics, is computationally very expensive. The BEM-CFD method is an enhanced actuator disk and is able to reduce the computational cost by simulating a time averag...

Flexible materials are integral to modern applications due to their unique properties, particularly their ability to stretch and resilience to fracture. However, predicting the fracture behaviour of these materials through simulations remains challenging, primarily due to the lack of numerical robustness. This study proposes a rate-independent phas...

Ground-mounted photovoltaics are established as a form of renewable energy conversion. However, limitations on land coverage hinders their development, particularly in urban environments. As a solution, Floating PhotoVoltaics (FPV) technology has been developed for lakes and marine environments. This design can make a significant contribution to an...

Natural Rubber are typically subjected to high cyclic loading conditions during their service lives necessitating the importance of developing multifunctional rubbers with appropriate performance under alternating loading. Carbon Nanotubes (CNTs) were extensively used to tailor mechanical properties of rubbers while their performances are severely...

Traditional Acoustic Doppler Current Profiler (ADCP) instruments measure marine flow velocities along diverging acoustic beams. This allows estimation of approximate mean velocity and turbulence at a point between the beams. Alternatively, a converging beam instrument can measure velocity components at a single point and hence provide a higher qual...

This study presents the results of a collaborative effort between academia and industry aimed at further enhancing the benefits provided by Vortex Generators and Gurney Flaps. To achieve this objective, an integrated approach was employed, involving wind tunnel experiments, on-site measurements, and computational simulations to design devices tailo...

In recent years, there has been a notable increase in interest towards Flexible Wave Energy Converters (FlexWECs). These flexible energy harvesters solve structural design challenges faced by rigid-body WECs by responding to external loading by changing shapes. Typically, the structures are made from rubber-like materials which pose few challenges...

Accurate assessment of marine currents is critical for meaningful planning of tidal stream energy deployments. Methods for assessing mean flow speed are well-established, but the issue of assessing phenomena that vary over much shorter time scales than the semidiurnal tide (principally turbulence and waves) is not as settled. This is in part due to...

This paper presents the first blind prediction stage of the Tidal Turbine Benchmarking Project being conducted and funded by the UK's EPSRC and Supergen ORE Hub. In this first stage, only steady flow conditions, at low and elevated turbulence (3.1%) levels, were considered. Prior to the blind prediction stage, a large laboratory scale experiment wa...

There were huge discrepancies in the existing literature for biaxial tests in terms of sample configuration (square or cruciform specimens), dimension, and test setups such as strain rate, pre-loading, equi-biaxial or unequi-biaxial. In addition, there exist limited works on the biaxial characterization of soft polymers, thus making it difficult to...

Natural rubber used in wave energy converters requires higher fatigue life and better energy harvesting efficiency to make it inexpensive compared to other renewable energy resources. Carbon nanotubes (CNTs) were extensively used to enhance the mechanical properties of natural rubber, however, its performance in a double-bonded shear condition was...

Mechanical characterizations of natural rubber filled with carbon-based nanomaterials were extensively studied in tensile and tear modes whereas fewer attempts have been conducted on a dynamic shear condition using a double-bonded shear test piece. This is of importance since natural rubbers are widely used as flexible membranes for wave energy har...

The transient response of elastomeric polymers is dependent on polymer composition, temperature and the loading history. In particular, hysteresis, dissipation and creep are significant in the choice of material for elastomer membrane wave energy converters. Natural rubber is a good candidate when looking for material for a wave energy harvester si...

CFD models of marine turbines often assumes constant depth. However, the presence of seabed bathymetry creates a significantly complex flow environment. In this paper, the bathymetry of a potential tidal deployment site is used in the development of a CFD model. Both URANS and DES turbulence approach for simulating marine currents around tidal ener...

A system for generating renewable energy from fast flowing rivers has been designed in a previous project. It uses a purely mechanical system to pump pressurised water to shore. Here we describe the development of a 0.9m version of this system, designed for installation in a tidal estuary. The system is fully instrumented to allow power take off an...

Wave Energy Converter (WEC) performance is generally sensitive to the wave direction. So, it is important to include the effect of multi-directional waves in numerical modelling. A realistic representation of ocean waves should account for wave height and directional spreading parameters specific to the WEC deployment location. A high quality gener...

Marine renewable energy site and resource characterisation, in particular tidal stream energy, require detailed flow measurements which often rely on high-cost in situ instrumentation which is limited in spatial extent. We hypothesise uncrewed aerial vehicles (UAV) offer a low-cost and low-risk data collection method for tidal stream environments,...

Resource quantification is vital in developing a tidal stream energy site but challenging in high energy areas. Drone-based large-scale particle image velocimetry (LSPIV) may provide a novel, low cost, low risk approach that improves spatial coverage compared to ADCP methods. For the first time, this study quantifies performance of the technique fo...

Coupled blade element momentum-computational fluid dynamic (BEM-CFD) approaches have been extensively used to study tidal stream turbine performance and wake development. These approaches have shown to be accurate when compared to tests conducted in tow-tanks or in regulated flumes with uniform flows across the turbine. Whilst such studies can be v...

Wave Energy Converters (WECs) have not yet proven their competitiveness in the mainstream energy market. Research and development of this technology are necessary to find optimal solutions in terms both of energy produced and reduced cost. A WEC farm is expected to have reduced Levelized Cost of Energy (LCoE) compared to individual devices due to s...

Axial flow hydro-kinetic turbines convert the kinetic energy of a flowing fluid into electrical energy, and can be designed for deployment in a wide range of locations. As relatively recent technology, these designs are often high in cost, complex, and require specialist maintenance and materials. This is not viable for many communities in developi...

Numerical models are used for design and evaluation of tidal energy converters, helping to increase their appeal as significant contributors in the generation of low carbon energy. In this study, we quantify the improvement in predicted structural load variability achieved by incorporating more detailed consideration of foil shape and Reynolds effe...

Acoustic Doppler current profilers (ADCPs) are the standard tool for measuring tidal currents at tidal stream energy sites; they are used to estimate several parameters, including turbulent kinetic energy (TKE). However, estimates of TKE from ADCPs are often swamped by wave action. We surmise that this bias can be detected as a data mode: to test t...

A generalised actuator disk-computational fluid dynamics (GAD-CFD) model is used to conduct simulations on a 14-turbine array arranged in two different configurations. Firstly, simulations of a regular (staggered) and modified (dual) configurations are conducted in straight flow conditions to understand the hydrodynamics around devices and evaluate...

Tidal energy converters have the potential to become significant contributors in the generation of low carbon energy. Operational cost, driven mostly by planned and unplanned maintenance, is one of the most significant barrier limiting their widespread adoption. Accurate numerical models can be used to predict structural loads and help improve thei...

This research aims to implement a three-dimensional regional scale numerical model within a region of the Irish Sea (between 52.808˚N and 53.842˚N) that is suitable for turbine array implementation and impact assessment. This research is based on a three-dimensional wave-current-sediment fully coupled oceanographic model (FVCOM), and modifications...

We present a new combined method for separation of wave and turbulence effects in Acoustic Doppler Current Profiler (ADCP) measurements of Turbulent Kinetic Energy (TKE). TKE is conventionally calculated from ADCP measurements using the variance method, but a straightforward application of this method attributes all velocity variance, including tha...

With a growing range of floating tidal energy converters being developed, tested and deployed the SURFTEC project aimed to measure and model the motion of this type of device. Part of this work included the design and development of a relatively low cost data logging and motion sensing system, deployed on a test device at two sites between 2017 and...

Whenever considering new tidal stream sites; information on current characteristics is of paramount importance. This contribution describes a methodology to measure surface currents at tidal stream sites using drones and provides initial validation of the approach against velocities measured by GPS surface drifters. Drones have the potential to mea...

The small area of the United Kingdom relative to weather systems makes renewable energy sources variable on short time scales. Short term variability is therefore a growing concern with increasing amounts of renewable energy integration. In this work, we address how tidal energy can contribute to reducing medium-term variability in the future UK en...

In the last decade, there has been a growing trend towards flexible body wave energy converters (WECs) enabled by rubber-like elastomeric composite membrane structures that can simplify all aspects of WEC design. Currently, there are few literature studies detailing the implementations of membranes into WEC design. This paper aims to overcome this...

The development of tidal energy converters, and particularly floating tidal energy converters, is an area of increased development in recent years. Testing of a floating tidal energy device over winter 2017/18 led to an opportunity to record and examine strain of a full scale composite turbine blade under operational conditions, with comparison of...

A computational model has been used to explore characteristics of the barotropic tide around the Welsh coast in detail for the first time. Proper understanding of tidal characteristics is vital for the sustainable use of marine resources; particularly for industries such as marine energy extraction, aggregate mining, aquaculture, as well as regulat...

Optimisation of Wave Energy Converters (WECs) is a very important topic to obtain competitive devices in the energy market. Wave energy is a renewable resource that could contribute significantly to a future sustainable world. Research is on-going to reduce costs and increase the amount of energy captured. This work aims to optimise a WaveSub devic...

Coastal dunes have global importance as ecological habitats, recreational areas, and vital natural coastal protection. Dunes evolve due to variations in the supply and removal of sediment via both wind and waves, and on stabilization through vegetation colonization and growth. One aspect of dune evolution that is poorly understood is the longshore...

Cost, driven mostly by planned and unplanned maintenance, is the most significant barrier limiting widespread adoption of TECs. Accurate numerical models can be used to predict the structural loads on TECs and help improve their reliability. BEMT offers an efficient method for predicting the performance of TECs. A robust but unoptimized BEMT code,...

The paper presents results from the Collaborative Computational Project in Wave Structure Interaction (CCP-WSI) Blind Test Series 2. Without prior access to the physical data, participants, with numerical methods ranging from low-fidelity linear models to fully nonlinear Navier-Stokes (NS) solvers, simulate the interaction between focused wave even...

A submerged wave device generates energy from the relative motion of floating bodies. In WaveSub, three floats are joined to a reactor; each connected to a spring and generator. Electricity generated damps the orbital movements of the floats. The forces are non-linear and each float interacts with the others. Tuning to the wave climate is achieved...

Numerical modelling of wave–structure interactions is a cost-effective alternative to physical models in understanding of marine energy device system behaviours and performance, though it is important to establish the reliability of the numerical model first. In this paper, experimental studies in which two surface-piercing floating buoys were subj...

Better understanding of the global wave climate is required to inform wave energy device design and large-scale deployment. Spatial variability in the global wave climate is analysed here to provide a range of characteristic design wave climates. K-means clustering was used to split the global wave resource into 6 classes in a device agnostic, data...

Turbulence is a crucial flow phenomenon for tidal energy converters (TECs), as it influences both the peak loads they experience and their fatigue life. To best mitigate its effects we must understand both turbulence itself and how it induces loads on TECs. To that end, this paper presents the results of blade element momentum theory (BEMT) simulat...

Wave Energy Converters (WECs) are very often simulated in bi-dimensional waves but a more accurate simulation that represents a more realistic sea state should account for multi-directional waves. In a first approximation directional distribution can be expressed as a Gaussian spreading model. Here we show a simulation of the WaveSub device in mult...

Flexible working devices take many forms. In this paper, we have proposed a methodology for classification based on the working surface. Three operational classifications have been devised based on the developments to date: Membrane Cell, Bulge Wave and Membrane Carpet. Additional operational classifications may be added following the same methodol...

As part of ongoing work to develop and validate a combined model for the behaviour and potential power generation of a floating tidal energy converter, the motion of a prototype device has been recorded over a two month testing period. The inputs from several types of sensor have been combined with GPS position information to improve accuracy of th...

Tidal turbine reliability is strongly affected by fluctuating loads induced by turbulence and waves at tidal energy sites. Turbulence is most often characterised through its intensity, which is the turbulent kinetic energy (TKE) scaled by the mean flow speed. The most common instrument for measuring TKE is the acoustic Doppler current profiler; how...

Temporal variability in renewable energy presents a major challenge for electrical grid systems. Tides are considered predictable due to their regular periodicity; however, the persistence and quality of tidal-stream generated electricity is unknown. This paper is the first study that attempts to address this knowledge gap through direct measuremen...

Proceedings of the 7th Oxford Tidal Energy Workshop 8 - 9 April 2019, Oxford, UK Workshop Organisers: Richard H. J. Willden (Chairman) University of Oxford Christopher R. Vogel (Co-Chairman) University of Oxford Scientific Committee Members: T. A. A. Adcock (University of Oxford) J. Thake (SIMEC Atlantis Energy) G. T. Houlsby (University of Oxford)...

Blue Growth is the creation of economic activity and jobs at sea, while multiple use of space makes efficient use of the available sea area by combining industries. Clearly there are many combinations and many value propositions. However, most technologies to date are considered blue sky concepts, with little robust techno-economic analysis demonst...

As anthropogenic use of the coastal zone diversifies, for example marine energy extraction, the coastal environments of interest to coastal engineers and managers is becoming more varied. Increasingly, the morphodynamics of geomorphologically complex, mixed sediment and geologically constrained beaches are important. Even in areas where erosion and...

The Severn Estuary (west coast of UK) is a highly dynamic environment and thus understanding of sediment transport under both natural and man-made changes is vital to the sustainable use of the coastal area in this region. The area is likely to be the site of the world’s first tidal energy lagoon. The construction and operation of the lagoon will r...

The optimization of Wave Energy Converters (WECs) is a current topic related to the development of the ocean wave energy sector. Competition between developers is based mainly on the minimization of the Levelized Cost Of Energy (LCOE). A particular numerical methodology is adopted. Nemoh is used for hydrodynamic computation and the standard linear...

Tidal energy is one of the most predictable forms of renewable energy. Although there has been much commercial and R&D progress in tidal stream energy, tidal range is a more mature technology, with tidal range power plants having a history that extends back over 50 years. With the 2017 publication of the "Hendry Review" that examined the feasibilit...

Tidal energy is one of the most predictable forms of renewable energy. Although there has been much commercial and R&D progress in tidal stream energy, tidal range is a more mature technology, with tidal range power plants having a history that extends back over 50 years. With the 2017 publication of the "Hendry Review" that examined the feasibilit...

Coastal and Marine Tourism & Leisure (T&L) is one of the Blue Economy (BE) sectors that can help unlock the potential of multi-use of space at sea by engaging with Blue Growth (BG) sectors such as Aquaculture and Marine Renewable Energy among others. BG aims to exploit opportunities in the offshore areas, coastal T&L is mainly based onshore with ve...

Extraction of energy from tidal streams has the potential to impact on the morphodynamics of areas such as sub-tidal sandbanks via alteration of hydrodynamics. Marine sediment transport is forced by both wave and tidal currents. Past work on tidal stream turbine impacts has largely ignored the contribution of waves. Here, a fully coupled hydrodynam...

Link to full pdf: https://www.riverpublishers.com/pdf/ebook/RP9788793609259.pdf Free ebook http://bit.ly/BlueGrowthBook Throughout the world there is evidence of mounting interest in marine resources and new maritime industries to create jobs, economic growth and to help in the provision of energy and food security. Expanding populations, insecu...

Acoustic Doppler current profilers (ADCPs) are commonly used to assess mean currents and turbulence at energetic sites. Since 2014, five-beam ADCP configurations have become more common, but conventional analysis of turbulence properties is still based on the four-beam Janus configuration. We use measurements from a single site to investigate impro...

The intermittent, irregular and variable nature of the wave energy resource has implications for the supply of wave-generated electricity into the grid; intermittency of renewable power may lead to frequency and voltage fluctuations in the transmission and distribution networks. This study analyses the wave resource over different spatial scales to...

The future growth of maritime activities may be limited due to competition for space as coastal areas become overcrowded. This has led to interest in promoting more efficient and sustainable use of the sea and its resources through the sharing of space. The MARIBE (MARine Investment for the Blue Economy) project investigated the potential of combin...

This study focuses on a comparison of model results from a blade element momentum computational fluid dynamics (BEM-CFD) steady state RANS model, and a BEMT model that accounts for the wake generated from upstream turbines using analytic expressions. Rotor forces are calculated using 3D hydrofoil profile data. Both techniques are validated against...

Field measurement of turbulence in strong tidal currents is difficult and expensive, but the tidal energy industry needs to accurately quantify turbulence for adequate resource characterisation and device design. Models that can predict such turbulence could reduce measurement costs. We compare a Regional Ocean Modelling System (ROMS) simulation wi...

This work aims to correlate a Blade Element Momentum CFD model with experimental results using a 0.28m diameter HATT rotor in a laboratory flume at Lehigh University. This study highlights the key issues with using this type of model for turbine prediction, and discusses the lessons learnt. The initial results show that the correlation fails to pre...

To meet the growing requirements of the tidal stream renewable energy sector, investment in improving current tidal stream power extraction knowledge and technology is necessary. This can be achieved through the study of practical experiment, or numerical and analytical modelling. The ability to capture and understand the flow characteristics of a...

This paper provides an assessment of the wave climate in South Wales, UK, focussing on buoy data. Additionally model results are used to provide information on spatial patterns in the resource. The main findings are mean wave power at the LCRI Waverider site is 18.1kW/m, 21.8kW/m at the West Pembrokeshire buoy and 17kW/m at the Turbot bank site. Th...

The main function of a marine renewable energy device is to remove energy from a marine environment and transform it into (generally) electrical energy for further use. This has potential for environmental benefits in the form of reducing global carbon emissions, but also has the potential for impact on the local ecology. Using computer models and...