Second-order wavemaker theory for irregular waves

Schäffer, Hemming A.

doi:10.1016/0029-8018(95)00013-b

Cited by 230 publications

(212 citation statements)

References 15 publications

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“…In shallow water conditions, it is well known that Stokes theory over predicts the magnitude of the second-order components. Schäffer (1996) introduced the nonlinearity parameter S; a value of S = 1 corresponding to the 'limiting' case where second-order Stokes theory predicts secondary peaks in the trough of the primary wave. As a result, for S > 1 the theory fails to predict the correct second-order content.…”

Section: Experimental Investigationmentioning

confidence: 99%

“…As a result, for S > 1 the theory fails to predict the correct second-order content. With the force-feedback model outlined in part I utilizing the wave field solution derived by Schäffer (1996), the nonlinearity factor S will also be applied herein. For a regular wave with angular frequency ω = 2πf , wavenumber k and wave height H, the nonlinearity factor S is given by …”

Section: Experimental Investigationmentioning

confidence: 99%

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Second-order wave maker theory using force-feedback control. Part II: An experimental verification of regular wave generation

Spinneken

Swan

2009

Ocean Engineering

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Section: Experimental Investigationmentioning

confidence: 99%

Section: Experimental Investigationmentioning

confidence: 99%

Second-order wave maker theory using force-feedback control. Part II: An experimental verification of regular wave generation

Spinneken

Swan

2009

Ocean Engineering

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“…This has been discussed extensively (Flick & Guza (1980), Sulisz & Hudspeth (1993), van Leeuwen & Klopman (1996), Schäffer (1996) and Zaman & Mak (2007)) and will not be repeated herein. Indeed, throughout this paper the notation and solution as presented by Schäffer (1996) will be adopted. With the wave field known, the wave-induced force acting on the paddle can be derived, representing part of the input to the paddle controller.…”

Section: Hydrodynamic Feedbackmentioning

confidence: 99%

“…In addition, Flick & Guza (1980) and Sulisz & Hudspeth (1993) addressed the effects of spurious superharmonic waves. In seeking an explanation of these effects, Schäffer (1996) derived a complete mathematical model for position-controlled wave makers including the sub-and superharmonic effects arising at second-order. With advances in laboratory wave generation techniques, wave makers are increasingly required to provide active absorption in order to avoid spurious reflection and reduce the flume or basin stilling time.…”

Section: Introductionmentioning

confidence: 99%

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Second-order wave maker theory using force-feedback control. Part I: A new theory for regular wave generation

Spinneken

Swan

2009

Ocean Engineering

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Second-order wave maker theory has long been established; the most extensive and detailed approach given by Schäffer (1996). However, all existing theories assume the wave paddle is driven by a positionfeedback motion controller. Early research in the wave power field led to the design of a force-controlled absorbing wave machine (Salter 1982). In addition to operating as an excellent absorber, this machine seemed to introduce very little spurious harmonic content when driven with a first-order command signal. The present paper provides a mathematical model for the operation of wave makers using force-feedback control and seeks to explain this apparent advantage. The model is developed to second-order so that a command signal compensating for the remaining spurious wave is also provided. Due to the complexity of the problem, the model has been limited to flap-type wave machines and the generation of regular waves. A variety of numerical tests in force-control mode have been conducted, indicating that the spurious wave content is greatly reduced when compared to the position-control mode. A separate experimental study validating the theory is presented in a part II paper by the same authors.

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Performance of dual‐chamber oscillating water column device under irregular incident waves using Reynolds averaged Navier–Stokes model

Koley,

Krishnan,

Ray

et al. 2024

Engineering Reports

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The purpose of this study is to analyze the hydrodynamic performance and efficiency of a dual‐chamber oscillating water column (OWC) device. For the Joint North Sea Wave Project (JONSWAP) incident waves spectrum, a two dimensional numerical wave tank is employed with nonlinear Reynolds averaged Navier–Stokes equations model along with the standard turbulence model. The free surface elevation is measured using the volume of fluid method. The numerical simulation demonstrates the streamline and velocity vector profiles throughout an entire pressure fluctuation cycle inside the chambers of the given OWC device. Further, investigation is carried out to analyze the impact of pressure drop and air flow rate through the orifice of the dual‐chamber OWC device on the power generation. Moreover, the power spectral density analysis of the free surface elevation is provided to know the variation of the parameters in the frequency domain. These results demonstrate that the effectiveness of the dual‐chamber OWC device is more near the significant wave height m.

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Second-order wavemaker theory for irregular waves

Cited by 230 publications

References 15 publications

Second-order wave maker theory using force-feedback control. Part II: An experimental verification of regular wave generation

Second-order wave maker theory using force-feedback control. Part II: An experimental verification of regular wave generation

Second-order wave maker theory using force-feedback control. Part I: A new theory for regular wave generation

Performance of dual‐chamber oscillating water column device under irregular incident waves using Reynolds averaged Navier–Stokes model

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