A New Control Method of Active Absorption Wave-Maker

2012 ◽  
Vol 591-593 ◽  
pp. 1748-1752
Author(s):  
Hong Wei Li ◽  
Yong Jie Pang ◽  
Guo Cheng Zhang
Keyword(s):  
Control Method ◽  
Wave Generation ◽  
Active Absorption ◽  
Reflected Waves ◽  
Wave Absorption ◽  
Numerical Wave Flume ◽  
Wave Flume ◽  
Wave Maker ◽  
Active Wave ◽  
Absorption Wave

The theory of 2D wave generation with active wave absorption is outlined. A new control method of active absorption wave-maker is established based on the S plane control (SPC) algorithm in this paper. Using SPC, a piston-type 2D numerical wave flume (NWF) simulation program for simultaneous wave generation and active wave absorption is developed with Boundary Element Method (BEM) and Mixed Eulerian-Lagrangian (MEL). The absorbing wave-making contrast simulation tests for regular wave are also carried out in NWF. Simulation results verify that the controller is robust and well effect for absorbing re-reflected wave is obtained in low reflect condition. Meanwhile, stable wave profile can be output by the absorbing wave-maker in a long time when acute reflected waves appear in the terminal of NWF.

A 3D Numerical Wave Tank for Coastal Engineering Studies

2017 ◽  
Vol 372 ◽  
pp. 1-10 ◽  
Author(s):  
Eric Didier ◽  
Paulo R.F. Teixeira ◽  
Maria Graça Neves
Keyword(s):  
Wave Tank ◽  
Active Absorption ◽  
Wave Flume ◽  
Long Time ◽  
Mean Water Level ◽  
Wave Maker ◽  
Numerical Beach ◽  
2D And 3D ◽  
3D Applications ◽  
Absorption Wave

This paper presents the validation of active and passive, made by a dissipation beach, numerical absorbing methods implemented in RANS-VOF FLUENT® code for modelling long time series of wave propagation interacting with coastal structures. Verification of both numerical techniques was performed in 2D – wave flume, and 3D – wave tank, this one using a multiple active absorption wave makers. The active absorption wave maker allows maintaining the incident wave generation and the mean water level along the time. Good results were obtained for 2D and 3D applications for active absorption wave maker at the generation boundary and both numerical beach and active absorption at the end of the flume/tank.

Numerical Study of Wave Slamming on a Rectangular Slab

2012 ◽  
Vol 204-208 ◽  
pp. 4971-4977
Author(s):  
Ya Mei Lan ◽  
Wen Hua Guo ◽  
Yong Guo Li
Keyword(s):  
Numerical Study ◽  
Navier Stokes ◽  
Governing Equations ◽  
Reflected Waves ◽  
Rans Equations ◽  
Numerical Wave Flume ◽  
Wave Flume ◽  
Wave Slamming ◽  
Numerical Wave ◽  
Rectangular Slab

The CFD software FLUENT was used as the foundation to develop the numerical wave flume, in which the governing equations are the Reynolds-averaged Navier-Stokes (RANS) equations and the standard k~ε turbulence model. The wave generating and absorbing were introduced into the RANS equations as the source terms using the relaxation approach. A new module of the wave generating and absorbing function, which is suitable for FLUENT based on the volume of fluid method (VOF), was established. Within the numerical wave flume, the reflected waves from the model within the computation domain can be absorbed effectively before second reflection appears due to the wave generating boundary. The computational results of the wave pressures on the bottom of the rectangular slab were validated for the different relative clearance by the experimental data. Good agreements were found.

Active Absorption of Random Waves in Wave Flume Using Artificial Neural Networks

2020 ◽  
Author(s):  
Áureo I. W. Ramos ◽  
Antonio C. Fernandes ◽  
Vanessa M. Thomaz
Keyword(s):  
Neural Networks ◽  
Artificial Neural Networks ◽  
Control Algorithm ◽  
Wave Generation ◽  
Reverse Direction ◽  
Small Scale ◽  
Wave Absorption ◽  
Wave Flume ◽  
Wave Channel ◽  
Artificial Neural

Abstract A wave flume is primarily intended to reproduce actual sea conditions in order to provide a reliable means of testing for small scale models. The realization of scaled tests is extremely important for the validation of a project in real scale, since, through the laws of similitude, such tests make it possible to predict the behavior of structures in the ocean as well as their performance during operation. This research aims to develop, test and validate an active control algorithm for wave absorption in a 2D wave channel — that is, when the waves propagate in only one direction — based on artificial neural networks (ANN). The ANN control algorithm relies on the linear wave theory and the principle of time reversal of wave propagation, i.e. the phenomenon of wave absorption corresponds to the wave generation when observed in the reverse direction of time. Through this principle, data from wave generation experiments, after proper manipulation, are used to train an ANN capable of generating the control signal used to move the wave generator device, this time as a wave absorber.

Experimental Validation of an Absorbing Wavemaker Controller

2009 ◽  
Author(s):  
Mario L. Carneiro ◽  
Pedro C. de Mello ◽  
Eduardo A. Tannuri ◽  
Alexandre N. Simos
Keyword(s):  
Evanescent Wave ◽  
Simulation Models ◽  
Calibration Procedure ◽  
Absorption Efficiency ◽  
Active Absorption ◽  
Reflected Waves ◽  
Original Algorithm ◽  
Wave Flume ◽  
High Frequency Oscillations ◽  
Implementation Problems

A new Active Absorption Basin (AAB) is under development, and will be used for the calibration of simulation models developed in the Numerical Offshore Tank of University of Sa˜o Paulo (TPN-USP). The AAB will be equipped with 148 independent flap-type wave makers arranged around its 14×14m rectangular section. Due to the small dimensions of the tank, it is necessary to use active absorption, in order to avoid the contamination of the wave field by the reflected waves, allowing the emulation of the infinite multi-directional ocean behavior. The wave maker actuation feedback control is based on the measurement of surface elevation at each flap, as proposed by [1]. The generation-absorption algorithm disregards the evanescent wave modes that are present in the sensor measurements. In the present paper, the absorption algorithm was tested in a 2D wave flume. A wave probe array installed in the middle of the flume was used to check the quality of the absorption algorithm. With this experiment, several implementation problems could then be identified and solved. High-frequency oscillations and drift of the flaps were observed using the original algorithm. Novel terms were then introduced, in order to reduce the overall gain of the controller, include the effect of the evanescent wave and eliminate the drift of position. The modified version of the algorithm was then used in an extensive calibration procedure for regular waves, in order to improve the absorption efficiency. Reflection coefficients smaller than 11% were obtained for waves up to 1,5Hz, proving the efficiency of the method.

scholarly journals Performance Assessment of Three Turbulence Models Validated through an Experimental Wave Flume under Different Scenarios of Wave Generation

2020 ◽  
Vol 8 (11) ◽  
pp. 881
Author(s):  
Lander Galera-Calero ◽  
Jesús María Blanco ◽  
Urko Izquierdo ◽  
Gustavo Adolfo Esteban
Keyword(s):  
Turbulence Model ◽  
Surface Displacement ◽  
Turbulence Models ◽  
Future Research ◽  
Reflected Waves ◽  
Numerical Wave Flume ◽  
Wave Flume ◽  
Free Surface Displacement ◽  
The Time Domain ◽  
The Waves

This study aimed to adjust the turbulence models to the real behavior of the numerical wave flume (NWF) and the future research that will be carried out on it, according to the turbulence model that best adjusts to each particular case study. The k-ε, k-ω and large-eddy simulation (LES) models, using the volume of fluid (VOF) method, were analyzed and compared respectively. The wavemaker theory was followed to faithfully reproduce the waves, which were measured in an experimental wave flume (EWF) and compared with the theory to validate each turbulence model. Besides, reflection was measured with the Mansard and Funke method, which has shown promising results when studying one of the most critical turbulent behaviors in the wave flume, called the breaking of the waves. The free surface displacement obtained with each turbulence model was compared with the recorded signals located at three points of the experimental wave flume, in the time domain of each run, respectively. Finally, the calculated reflection coefficients and the amplitudes of the reflected waves were compared, aiming to have a better understanding of the wave reflection process at the extinction zone. The research showed good agreement between all the experimental signals and the numerical outcomes for all the turbulence models analyzed.

Numerical Model of Wave Flume

2011 ◽  
Vol 138-139 ◽  
pp. 79-84
Author(s):  
Ya Mei Lan ◽  
Yong Guo Li ◽  
Wen Hua Guo
Keyword(s):  
Stokes Equations ◽  
Navier Stokes ◽  
Volume Of Fluid Method ◽  
Governing Equations ◽  
Navier Stokes Equations ◽  
Reflected Waves ◽  
Numerical Wave Flume ◽  
Wave Flume ◽  
Computation Efficiency ◽  
Volume Method

Based on the finite volume method, the Navier-Stokes equations was used as the governing equations to develop a new module of the wave generating and absorbing function. The wave generating was introduced as the man-made source terms into the momentum equations, which was suitable for the volume of fluid method (VOF). Within the numerical wave flume, the reflected waves from the construction could be absorbed effectively. The absorbing section arranged at the end of the wave flume was for absorbing the incident wave, which allows for random and effective working time within the reletively smaller computation domain. Consequently, the computation efficiency was greatly improved. Finally, the validity of the absorbing section arranged at the front and end of the wave flume was investigated individually.

Realistic wave generation and active wave absorption for Navier–Stokes models

2013 ◽  
Vol 71 ◽  
pp. 102-118 ◽  
Author(s):  
Pablo Higuera ◽  
Javier L. Lara ◽  
Inigo J. Losada
Keyword(s):  
Wave Generation ◽  
Navier Stokes ◽  
Wave Absorption ◽  
Active Wave

Experimental Wave Generation and Cancellation With a Cycloidal Wave Energy Converter

2011 ◽  
Author(s):  
Stefan G. Siegel ◽  
Marcus Ro¨mer ◽  
John Imamura ◽  
Casey Fagley ◽  
Thomas McLaughlin
Keyword(s):  
Wave Energy ◽  
Water Waves ◽  
Wave Generation ◽  
Wave Energy Converter ◽  
Design Parameters ◽  
Main Shaft ◽  
Energy Converter ◽  
Incoming Wave ◽  
Wave Flume ◽  
Wave Maker

We investigate a lift based wave energy converter (WEC), namely, a cycloidal turbine, as a wave termination device. A cycloidal turbine employs the same geometry as the well established Cycloidal or Voith-Schneider Propeller. The main shaft is aligned parallel to the wave crests and fully submerged at a fixed depth. We show that the geometry of the Cycloidal WEC is suitable for single sided wave generation as well as wave termination of straight crested waves using feedback control.The cycloidal WEC consists of a shaft and one or more hydrofoils that are attached eccentrically to the main shaft. An experimental investigation into the wave generation capabilities of the WEC are presented in this paper, along with initial wave cancellation results for deep water waves. The experiments are conducted in a small 2D wave flume equipped with a flap type wave maker as well as a 1:4 sloped beach. The operation of the Cycloidal WEC both as a wave generator as well as a wave energy converter interacting with a linear Airy wave is demonstrated. The influence that design parameters radius and submergence depth on the performance of the WEC have is shown. For wave cancellation, the incoming wave is reduced in amplitude by ≈ 80% in these experiments. In this case wave termination efficiencies of up to 95% of the incoming wave energy with neglegible harmonic waves generated are achieved by synchronizing the rotational rate and phase of the Cycloidal WEC to the incoming wave.

Wave-based active vibration control of a membrane structure

2021 ◽  
pp. 107754632110429
Author(s):  
Xiang Liu ◽  
Liangliang Lv ◽  
Fujun Peng ◽  
Guoping Cai
Keyword(s):  
Vibration Control ◽  
Membrane Structure ◽  
Control Method ◽  
Active Vibration Control ◽  
Standing Waves ◽  
Vibration Modes ◽  
Control Laws ◽  
Reflected Waves ◽  
Active Vibration ◽  
Active Wave

Wave-based active vibration control of a membrane structure by using the Active Sink Method is studied in this paper. Unlike the modal-based vibration control method which attempts to suppress several vibration modes that have already been excited, wave-based active controller can keep vibration modes inactive by stopping the formation of standing waves in the structure. First, the wave transfer matrix is deduced to characterize the wave transmission in the membrane structure. Then, feedforward wave control laws are derived analytically to absorb reflected waves or eliminate transmitted waves. The validity of the proposed active wave controllers is verified through numerical simulations. Simulation results show that by using the active wave controllers no standing waves will be produced in the structure, and the vibration of the membrane structure is suppressed significantly.

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