Electromagnetic acoustic transducers (EMATs) are increasingly used in industries due to their attractive features of being non-contact, cost-effective and the fact that a variety of wave modes can be generated, etc. There are two major EMATs coupling mechanisms: the Lorentz force mechanism for conductive materials and the magnetostriction mechanism for ferromagnetic materials; EMATs operated on Lorentz force mechanism are the focus of this study. This work aims to investigate novel efficient modelling techniques for EMATs, in order to gain further knowledge and understanding of EMATs wave pattern, how design parameters affect its wave pattern and based on above propose and optimise novel sensor structures. In this study, two novel modelling methods were proposed: one is the method combining the analytical method for EM simulation and the finite-difference time-domain (FDTD) method for US simulation for studying the Rayleigh waves' properties on the vertical plane of the material; the other one is the method utilizing a wholly analytical model to explore the directivity of surface waves. Both simulations models have been validated experimentally. The wholly analytical model generates the radiation pattern of surface waves, which lays a solid foundation for the optimum design of such sensors. The beam directivity of surface waves was investigated experimentally, and results showed the length of wires has a significant effect on the beam directivity of Rayleigh waves. A novel configuration of EMATs, variable-length meander-line-coil (VLMLC), was proposed and designed. The beam directivity of surface waves generated by such novel EMATs were analytically investigated. Experiments were conducted to validate such novel EMATs models, and results indicated that such EMATs are capable of supressing side lobes, and therefore resulting in a more concentrated surface waves in the desired direction. Further, another two novel configuration of EMATs, the four-directional meander-line-coil (FDMLC) and the six-directional meander-line-coil (SDMLC), were proposed and designed; results showed these EMATs are capable of generating Rayleigh waves in multiple directions and at the same time suppressing side lobes.

In this thesis, a model has been developed to analyze the behavior of wave energy converter arrays in the frequency domain. This development serves the purpose of establishing an in-house model tool for array modelling for CorPower Ocean. A literature review has been conducted to compare various modelling approaches and prior studies on different configurations of wave energy converter arrays have been examined. The literature review is followed by theory that includes linear wave theory and the equation of motion. Following this, the model is introduced, accompanied by behavior validation in comparison to similar models. The selected case studies for this thesis are divided into two parts. Firstly, the investigation of different layout configurations with 16 Wave Energy Converters: 1) Circular configuration, 2) Double Circular configuration, 3) Double Row configuration (2x8), 4) Square Grid configuration (4x4), and 5) Randomized layout. The second chosen study case involves investigating layout 3) Double Row configuration (2x8) with four different distances between each Wave Energy Converter, 50, 100, 150, and 200 meters. The results demonstrate the presence of interactions within the wave energy converter arrays. The Double row layout exhibits the largest power outputs but power drops at certain waveperiods were also observed. Additionally, the results of different distances between the Wave Energy Converters demonstrate that larger spacings result in reduced interactions.