Analytical prediction of reflection coefficients for wave absorbing layers in flow simulations of regular free-surface waves

Perić, Robinson; Abdel‐Maksoud, Moustafa

doi:10.1016/j.oceaneng.2017.10.009

Cited by 44 publications

(24 citation statements)

References 39 publications

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“…Furthermore, reflection analysis demonstrates the transparency of the wavemaker region and the ability of the numerical beach to achieve arbitrarily low reflection. In the future, the work of [26] will allow setting the ideal beach parameters without the need to run parameter or calibration studies.…”

Section: Discussionmentioning

confidence: 99%

“…Perić and Abdel-Maksoud [26] recently published a method based on analytical theory to find the ideal magnitude of the damping parameter sand for monochromatic waves. In the future, it will thus be possible to set the ideal damping parameters prior to each simulation.…”

Section: Calibration Of the Numerical Beachmentioning

confidence: 99%

“…Perić and Abdel-Maksoud [26] recently derived an analytical solution describing the ideal setting for sand and validated the method in a numerical experiment, removing the need for parameter studies in the future.…”

mentioning

confidence: 99%

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The Efficient Application of an Impulse Source Wavemaker to CFD Simulations

Schmitt

Windt

Davidson

et al. 2019

JMSE

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Computational Fluid Dynamics (CFD) simulations, based on Reynolds-AveragedNavier–Stokes (RANS) models, are a useful tool for a wide range of coastal and offshore applications,providing a high fidelity representation of the underlying hydrodynamic processes. Generating inputwaves in the CFD simulation is performed by a Numerical Wavemaker (NWM), with a variety ofdifferent NWM methods existing for this task. While NWMs, based on impulse source methods, havebeen widely applied for wave generation in depth averaged, shallow water models, they have notseen the same level of adoption in the more general RANS-based CFD simulations, due to difficultiesin relating the required impulse source function to the resulting free surface elevation for non-shallowwater cases. This paper presents an implementation of an impulse source wavemaker, which is ableto self-calibrate the impulse source function to produce a desired wave series in deep or shallowwater at a specific point in time and space. Example applications are presented, for a NumericalWave Tank (NWT), based on the open-source CFD software OpenFOAM, for wave packets in deepand shallow water, highlighting the correct calibration of phase and amplitude. Furthermore, thesuitability for cases requiring very low reflection from NWT boundaries is demonstrated. Possibleissues in the use of the method are discussed, and guidance for accurate application is given.

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Section: Discussionmentioning

confidence: 99%

Section: Calibration Of the Numerical Beachmentioning

confidence: 99%

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The Efficient Application of an Impulse Source Wavemaker to CFD Simulations

Schmitt

Windt

Davidson

et al. 2019

JMSE

View full text Add to dashboard Cite

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“…Numerical beaches at both ends of the wave tank minimised internal reflections. A suitable distribution of the variable sand over a length of approximately one wavelength effectively dissipates wave energy as has been shown by [20,31]. Peric et al provides an analytical solution for the ideal settings depending on wave period and discusses the method in detail [31] .…”

Section: Numerical Experimentsmentioning

confidence: 99%

“…A suitable distribution of the variable sand over a length of approximately one wavelength effectively dissipates wave energy as has been shown by [20,31]. Peric et al provides an analytical solution for the ideal settings depending on wave period and discusses the method in detail [31] . Values for the current simulations were based on a previous study [20] and shown to reduce internal reflection to less than 0.5%.…”

Section: Numerical Experimentsmentioning

confidence: 99%

Obtaining Reflection Coefficients from a Single Point Velocity Measurement

McKee

Elsäßer

Schmitt

2018

JMSE

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The quantification of the reflection of water waves is of paramount importance in coastal and marine engineering. Reflected waves are produced as a result of an incident wave meeting a reflective boundary e.g., in a wave basin. While reflection can be seen as an undesirable disturbance, for example in experimental tests performed in confined tanks, it can also have a useful purpose such as being directed towards wave energy converters (WECs). Whether useful or not, reflection needs to be accurately quantified. For cases effected by directional spreading such as WECs, the wave height of a reflected wave will be spatially variable. The majority of quantification methods are based on frequency domain analysis of surface elevation data at more than one discrete location over approximately one wavelength. Thus, a method which requires a single point measurement is desirable. This paper presents a novel method derived from Linear Wave theory to quantify reflection coefficients using orbital velocity measurements at one discrete location. An additional advantage of this method is it only requires data over a single wave cycle and thus will be particularly suitable for numerical simulations. In the present form the method is only applicable to monochromatic waves. The theoretical background of the method is explained in detail. An application is demonstrated through a comparison to reflections quantified using surface elevation measurements in Computational Fluid Dynamics (CFD) numerical simulations. It is found that the results of the new proposed method compare to surface elevation methods within the levels of experimental accuracy.

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An efficient quasi‐Newton method for two‐dimensional steady free surface flow

Demeester

Brummelen

Degroote

2020

Numerical Methods in Fluids

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Steady free surface flows are of interest in the fields of marine and hydraulic engineering. Fitting methods are generally used to represent the free surface position with a deforming grid. Existing fitting methods tend to use time-stepping schemes, which is inefficient for steady flows. There also exists a steady iterative method, but that one needs to be implemented with a dedicated solver.Therefore a new method is proposed to efficiently simulate two-dimensional (2D) steady free surface flows, suitable for use in conjunction with black-box flow solvers. The free surface position is calculated with a quasi-Newton method, where the approximate Jacobian is constructed in a novel way by combining data from past iterations with an analytical model based on a perturbation analysis of a potential flow. The method is tested on two 2D cases: the flow over a bottom topography and the flow over a hydrofoil. For all simulations the new method converges exponentially and in few iterations. Furthermore, convergence is independent of the free surface mesh size for all tests. K E Y W O R D Sfitting method, free surface flow, perturbation analysis, quasi-Newton INTRODUCTIONThis paper considers the numerical simulation of steady free surface flow of incompressible, immiscible fluids with a large density difference, typically water and air. This type of flow is often encountered in the fields of marine and hydraulic engineering, for example to calculate ship hull resistance, analyze ship-wall interactions in narrow straight canals and study flow behavior in river confluences. These flows are governed by the incompressible Navier-Stokes equations, which are typically solved with computational fluid dynamics (CFD). The free surface causes additional difficulties for the flow computations: its position is unknown a priori, and needs to be determined as a component of the solution during the computation. Two classes of methods exist to represent the free surface, namely, surface capturing and surface fitting methods. * In surface capturing approaches, the computational mesh is not aligned with the interface, and the interface can intersect the mesh in an in principle arbitrary manner. Capturing methods are versatile in that they can handle complex phenomena such as wave breaking. Examples are the marker-and-cell method, 2 the volume-of-fluid method, 3 and the level-set method. 4 *Classification and terminology of these methods tends to be inconsistent in the literature; terminology is adopted from Wackers et al. 1Int J Numer Meth Fluids. 2020;92:785-801.wileyonlinelibrary.com/journal/fld

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Analytical prediction of reflection coefficients for wave absorbing layers in flow simulations of regular free-surface waves

Cited by 44 publications

References 39 publications

The Efficient Application of an Impulse Source Wavemaker to CFD Simulations

The Efficient Application of an Impulse Source Wavemaker to CFD Simulations

Obtaining Reflection Coefficients from a Single Point Velocity Measurement

An efficient quasi‐Newton method for two‐dimensional steady free surface flow

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