scholarly journals Mathematical and Numerical Modelling of Wave Impact on Wave-Energy Buoys

2016 ◽  
Author(s):  
A. Kalogirou ◽  
O. Bokhove
Keyword(s):  
Numerical Modelling ◽  
Cross Sections ◽  
Wave Energy ◽  
Water Waves ◽  
Wave Equations ◽  
Rogue Waves ◽  
Scale Model ◽  
Wave Impact ◽  
Energy Device ◽  
Surface Deviation

We report on the mathematical and numerical modelling of amplified rogue waves driving a wave-energy device in a contraction. This wave-energy device consists of a floating buoy attached to an AC-induction motor and constrained to move upward only in a contraction, for which we have realised a working scale-model. A coupled Hamiltonian system is derived for the dynamics of water waves and moving wave-energy buoys. This nonlinear model consists of the classical water wave equations for the free surface deviation and velocity potential, coupled to a set of equations describing the dynamics of a wave-energy buoy. As a stepping stone, the model is solved numerically for the case of linear shallow water waves causing the motion of a simple buoy structure with V-shaped cross-sections, using a variational (dis)continuous Galerkin finite element method.

Characteristics of solitary waves, quasiperiodic solutions, homoclinic breather solutions and rogue waves in the generalized variable-coefficient forced Kadomtsev–Petviashvili equation

2017 ◽  
Vol 31 (36) ◽  
pp. 1750350 ◽  
Author(s):  
Xue-Wei Yan ◽  
Shou-Fu Tian ◽  
Min-Jie Dong ◽  
Li Zou
Keyword(s):  
Solitary Waves ◽  
Water Waves ◽  
Variable Coefficient ◽  
Wave Equations ◽  
Direct Method ◽  
Dynamical Behavior ◽  
Rogue Waves ◽  
Nonlinear Wave Equations ◽  
Quasiperiodic Solutions ◽  
Petviashvili Equation

In this paper, the generalized variable-coefficient forced Kadomtsev–Petviashvili (gvcfKP) equation is investigated, which can be used to characterize the water waves of long wavelength relating to nonlinear restoring forces. Using a dependent variable transformation and combining the Bell’s polynomials, we accurately derive the bilinear expression for the gvcfKP equation. By virtue of bilinear expression, its solitary waves are computed in a very direct method. By using the Riemann theta function, we derive the quasiperiodic solutions for the equation under some limitation factors. Besides, an effective way can be used to calculate its homoclinic breather waves and rogue waves, respectively, by using an extended homoclinic test function. We hope that our results can help enrich the dynamical behavior of the nonlinear wave equations with variable-coefficient.

Numerical modelling and wave tank testing of a self-reacting two-body wave energy device

2019 ◽  
Vol 14 (sup1) ◽  
pp. 344-356 ◽  
Author(s):  
Adi Kurniawan ◽  
Matthias Grassow ◽  
Francesco Ferri
Keyword(s):  
Numerical Modelling ◽  
Wave Energy ◽  
Body Wave ◽  
Energy Device ◽  
Wave Tank

Rogue-wave-energy: wave-to-wire mathematical modelling

2020 ◽  
Author(s):  
Onno Bokhove
Keyword(s):  
Wave Energy ◽  
Water Waves ◽  
Variational Principles ◽  
Rogue Wave ◽  
Cylindrical Tube ◽  
Wave Climate ◽  
Symplectic Integrators ◽  
Energy Device ◽  
Electro Magnetic ◽  
Magnetic Generator

<p>A novel wave-energy device design [1,2] will be presented based on the following features: (i) an electro-magnetic generator based on cylindrical magnets moving through induction wires around a cylindrical tube, like in the IP wave-buoy, (ii) a convergence in a breakwater to amplify the incoming waves, like in the TapChan device, and (iii) a wave-activated buoy with magnets attached, like in the Berkeley wedge, constrained to move in a slight arc or in a rectilinear manner. Its workings will be demonstrated in a first, operating proof-of-principle. A monolithic mathematical model is established by coupling the three variational principles for the hydro-dynamic wave motion, using the potential-flow approximation, the constrained wave-activated buoy motion, and the electro-magnetic generator together into one grand variational principle. The resistive losses in the electrical circuit and the energy harvested in the (parallel LED) loads are subsequently added to the dynamics. After linearisation of the resulting full 3D nonlinear model around a state of rest and application of the shallow-water approximation, we discretize the linear dynamics in a compatible, i.e. geometrically consistent, manner using a finite-element approach in space and symplectic integrators in time. Preliminary numerical modelling and simple optimization will be shown and these are promising. Finally, further optimisation of the device for different geometries and for a given wave-climate as well as alternative designs will be discussed.<br><br></p><p><strong>References<br></strong>[1] O. Bokhove, A. Kalogirou, W. Zweers 2019: From bore-soliton-splash to a new wave-to-wire wave-energy model. Water Waves<strong> 1</strong>.<br>[2] O. Bokhove, A. Kalgirou, D. Henry, G. Thomas 2019: A novel rogue-wave-energy device with wave amplification and induction actuator. In: 13th European Wave and Tidal Energy Conference 2019, Napoli, Italy.</p>

Wave Loading on a Moored OWC Wave Energy Device

2004 ◽  
Author(s):  
Timothy Finnigan
Keyword(s):  
Wave Energy ◽  
Scale Model ◽  
Mooring Line ◽  
Energy Device ◽  
Mooring Lines ◽  
Response Characteristics ◽  
Chamber Model ◽  
Design Requirements ◽  
Scale Design ◽  
The Waves

This paper describes results from wave tank testing on a 1/25 scale model of a moored oscillating water column (OWC) wave energy device. The device incorporates a piece-wise linear parabolic wall to focus the waves onto a three-sided OWC chamber. Model tests were conducted to determine the mooring line loads and associated structure motions in both a taut-moored floating configuration and a semi-fixed configuration. All six degrees of motion were recorded continuously along with forces in twelve mooring lines. Tests were conducted for a range of wave conditions and angles of incidence. For a device with a 35m wide parabolic wall (prototype scale), peak mooring line forces below 350Te were measured. In extreme conditions, heave motions were found to exceed design requirements in the floating configuration but this was rectified in the semi-fixed configuration. The paper presents a summary of the average results found and some of the dynamic response characteristics of the structure in various sea conditions. Implications for full-scale design and operation of the device are also discussed.

scholarly journals A novel wave-energy device with enhanced wave amplification and induction actuator

2020 ◽  
Vol 3 (1) ◽  
pp. 37-44
Author(s):  
Onno Bokhove ◽  
Anna Kalogirou ◽  
David Henry ◽  
Gareth P. Thomas
Keyword(s):  
Variational Principle ◽  
Numerical Model ◽  
Energy Conversion ◽  
Wave Energy ◽  
Electrical Power ◽  
Rogue Waves ◽  
Energy Device ◽  
Wave Amplification ◽  
Energy Devices ◽  
New Device

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.

Experimental Study on the Dynamic Response of a Moored Floating Wave Energy Device

2003 ◽  
Author(s):  
E. Vijayakrishna Rapaka ◽  
R. Natarajan ◽  
S. Neelamani
Keyword(s):  
Wave Energy ◽  
Damping Ratio ◽  
Wave Length ◽  
Scale Model ◽  
Mooring Line ◽  
Ocean Engineering ◽  
Energy Device ◽  
Mooring Lines ◽  
Wave Flume ◽  
Engineering Department

A detailed experimental investigation conducted on a moored Oscillating Water Column (OWC) wave energy device has been reported in this paper. The experiments were conducted on 1:20 scale model of the wave energy device, which was moored to the bed using 6 mooring lines in a 2m wide (deep and shallow water) wave flume at Ocean Engineering Department, IITM, Chennai. A range of hydrodynamic parameters with different damping ratio of the OWC chamber at scope 4 (length of the mooring line/depth of water) for a constant water depth was used. The effect of non-dimensionalized parameters like non-dimensionlized wave frequency parameter (ω2B/2g) and device breadth to wave length ratio (B/L) on the mooring force and on the efficiency of the wave energy device has been studied. The motion responses and mooring forces were measured and the test results are analysed and presented with discussions in this paper.

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