Abstract

A novel wave-energy device is presented. Both a preliminary proof-of-principle of a working, scaled laboratory version of the energy device is shown as well as the derivation and analysis of a comprehensive mathematical and numerical model of the new device. The wave-energy device includes a convergence in which the waves are amplified, a constrained wave buoy with a (curved) mast and direct energy conversion of the buoy motion into electrical power via an electro-magnetic generator. The device is designed for use in breakwaters and it is possible to be taken out of action during severe weather. The new design is a deconstruction of elements of existing wave-energy devices, such as the TapChan, IP wave-buoy and the Berkeley Wedge, put together in a different manner to enhance energy conversion and, hence, efficiency. The idea of wave-focusing in a contraction emerged from our work on creating and simulating rogue waves in crossing seas, including a "bore-soliton-splash". Such crossing seas have been recreated and modelled in the laboratory and in simulations by using a geometric channel convergence. The mathematical and numerical modelling is also novel. One monolithic variational principle governs the dynamics including the combined (potential-flow) hydrodynamics, the buoy motion and the power generation, to which the dissipative elements such as the electrical resistance of the circuits, coils and loads have been added a posteriori. The numerical model is a direct and consistent discretisation of this comprehensive variational principle. Preliminary numerical calculations are shown for the case of linearised dynamics; optimisation of efficiency is a target of future work.

Highlights

  • MOTIVATED by previous research on shallowwater and shallow-granular flows through contracting channels, and by water-wave impact against sea walls, a series of ad-hoc experiments have beenManuscript received 16 March; accepted 27 March; published 12 May, 2020

  • In the absence of the dissipative effects caused by the resistance of electrical circuits, induction coils and LED loads, the dynamics can be derived from a single variational principle (VP), detailed in Appendix A

  • Buoy motion and electro-magnetic currents are coupled through the connecting function G(Z) defined in (5), which appears in the equation (7f) for the vertical acceleration

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Summary

INTRODUCTION

MOTIVATED by previous research on shallowwater and shallow-granular flows through contracting channels, and by water-wave impact against sea walls, a series of ad-hoc experiments have been. Manuscript received 16 March; accepted 27 March; published 12 May, 2020. This article has been subject to single-blind peer review by a minimum of two reviewers. This is follow-up research that grew out of EPSRC grant EP/L025388/1 for O.

Kalogirou
MATHEMATICAL MODEL OF THE DEVICE
LINEARISATION AND DISCRETISATION
RESULTS
DISCUSSION

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