Weakly nonlinear theory for oscillating wave surge converters in a channel

Michele, Simone; Sammarco, Paolo; d’Errico, Michele

doi:10.1017/jfm.2017.724

Cited by 30 publications

(25 citation statements)

References 45 publications

(59 reference statements)

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“…Physically, trapped modes of a gate barrier are described by unforced, self-sustained fluid oscillations that decay exponentially from the gates and that do not lose energy through wave radiation (Mei et al 2005). We remark that the wave trapping phenomenon is of considerable interest in several applications such as acoustic resonance in pipes (Hein & Koch 2008), gratings (Porter & Evans 1999), thin elastic plates (Porter 2007), waveguides (Linton & Ratcliffe 2004;Callan et al 1991), open channels , cylinders in a channel (Evans & Porter 1997;Utsunomya & Taylor 1997), edge waves (Blondeaux & Vittori 1995;Li 2007), Venice gates (Li & Mei 2003;Sammarco et al 2013), internal waves (Nazarov & Videman 2009;Kuznetsov 1993) and wave energy conversion Michele et al (2018b).…”

Section: Introductionmentioning

confidence: 94%

Weakly nonlinear theory for a gate-type curved array in waves

2019

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We analyse the effect of gate surface curvature on the nonlinear behaviour of an array of gates in a semi-infinite channel. Using a perturbation-harmonic expansion, we show the occurrence of new detuning and damping terms in the Ginzburg–Landau evolution equation, which are not present in the case of flat gates. Unlike the case of linearised theories, synchronous excitation of trapped modes is now possible because of interactions between the wave field and the curved boundaries at higher orders. Finally, we apply the theory to the case of surging wave energy converters (WECs) with curved geometry and show that the effects of nonlinear synchronous resonance are substantial for design purposes. Conversely, in the case of subharmonic resonance we show that the effects of surface curvature are not always beneficial as previously thought.

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Section: Introductionmentioning

confidence: 94%

Weakly nonlinear theory for a gate-type curved array in waves

2019

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“…Note also that the maxima are located in correspondence to the first eigenfrequencies of the system, i.e., ω i = 0.99, 1.55, 2.24, 2.77, 3.66, 5.06 Rad s −1 . As in the case of oscillating wave surge converters and oscillating water columns [17,18,[20][21][22][23][24], resonance of natural modes is beneficial in terms of power extraction efficiency.…”

Section: Effects Of the Ptomentioning

confidence: 99%

Wave Energy Extraction by Flexible Floaters

et al. 2020

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We present a novel mathematical model to investigate the extraction of wave power by flexible floaters. The model is based on the method of dry modes, coupled with a matched eigenfunction expansion. Our model results compare satisfactorily with preliminary data obtained from a demonstrator device, developed at the University of Groningen. We show that the role of elasticity is to increase the number of resonant frequencies with respect to a rigid body, which has a positive effect on wave power output. The mathematical model is then extended to irregular incident waves, described by a JONSWAP spectrum. Our results show that the peak capture factors decrease in irregular waves, as compared to the monochromatic case. However, the system becomes more efficient at non-resonant frequencies. This work highlights the need to scale-up experimental investigations on flexible wave energy converters, which are still a small minority, compared to those on rigid converters.

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“…Analytical and semi-analytical theories have been used to model wave-OWSC interactions in linear and weakly nonlinear regimes (Renzi & Dias, 2012, 2013aRenzi et al, 2014a;Sarkar et al, 2014;Michele et al, 2015;Noad & Porter, 2015;Sarkar et al, 2016;Michele et al, 2016Michele et al, , 2018. Such theories are normally applied when the flap rotation is small, about 10 • from the vertical (Renzi & Dias, 2012).…”

Section: Experimental Pressure Time Seriesmentioning

confidence: 99%

The pressure impulse of wave slamming on an oscillating wave energy converter

Renzi

Wei

Dias

2018

Journal of Fluids and Structures

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Recent wave tank experiments on a flap-type wave energy converter showed the occurrence of extreme wave loads, corresponding to slamming events in highly energetic seas. In this paper, we analyse pressure-impulse values from available pressure measurements, for a series of experimental slamming tests. Then, we devise a pressure-impulse model of the slamming of a flapping plate, including the effects caused by air entrapment near the plate. Using a double conformal-mapping technique, we map the original domain into a semi-infinite channel, by means of Gauss' hypergeometric functions. This allows us to express the pressure impulse as a superimposition of orthogonal eigenfunctions in the transformed space. The mathematical model is validated against the experimental data. Parametric analysis shows that the system is much more sensitive to the impact angle than to the initial wetted portion of the flap. Furthermore, the presence of an aerated region determines the pressure-impulse values to increase significantly at all points on the flap surface.

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Weakly nonlinear theory for oscillating wave surge converters in a channel

Cited by 30 publications

References 45 publications

Weakly nonlinear theory for a gate-type curved array in waves

Weakly nonlinear theory for a gate-type curved array in waves

Wave Energy Extraction by Flexible Floaters

The pressure impulse of wave slamming on an oscillating wave energy converter

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