scholarly journals An optimal controller of an irregular wave maker

2005 ◽  
Vol 29 (1) ◽  
pp. 55-63 ◽  
Author(s):  
Ming Li
Keyword(s):  
Optimal Controller ◽  
Irregular Wave ◽  
Wave Maker

scholarly journals WAVES INDUCED BY NON-PERMANENT PADDLE MOVEMENTS

1972 ◽  
Vol 1 (13) ◽  
pp. 35 ◽  
Author(s):  
C. Campos Moraes ◽  
F. Silveira Ramos ◽  
M. Mendes De Carvalho
Keyword(s):  
Experimental Study ◽  
Gain Function ◽  
Surface Motion ◽  
Irregular Wave ◽  
Input And Output ◽  
Wave Maker

In a flume equipped with an irregular wave maker the motion of the paddle and the resulting waves may be thought of respectively as input and output of a system which, if linear, is for some purposes described by the so-called gain function. A theoretical and experimental study of this function is carried out ma king use of paddle movements that produce transient surface motion.

A Wave Maker With Active Reflected Wave Compensation System

2002 ◽  
Author(s):  
Fa´bio Nascimento ◽  
Carlos Levi ◽  
Antonio C. Fernandes ◽  
Paulo de Tarso Esperanc¸a ◽  
Paulo Sergio Gomes
Keyword(s):  
Control System ◽  
Real Time ◽  
Critical Issue ◽  
Compensation System ◽  
Irregular Waves ◽  
Real Time Control ◽  
Incoming Wave ◽  
Reflected Waves ◽  
Irregular Wave ◽  
Wave Maker

Important aspects in the studies to assess the dynamic behavior of ocean vessels or structures, like ships or offshore oil platforms is the capability of generating gravity waves under strict laboratory control. Model test techniques are continuously improving and are very much dependent on the good quality waves that could be generated in a basin. Since ocean basins have finite dimensions, the waves reflected by the models, walls and even to some extent by the beaches, may become a critical issue if you need to guarantee accuracy and reliability for the tests. Besides the undesirable pattern of reflected waves within the test area of the basin, these waves come back onto the wave maker, affecting the correct properties of the wave to be generated. Modern wave generator apparatuses are now being equipped with real time control systems that enable them to generate an irregular wave pattern. At the same time they correct their flap motions to compensate re-reflection of waves from the wave-boards. The quality of such a system depends very much on the efficiency of the algorithm to be implemented in it. This paper discusses the development of an effective mathematical model of a control system used in an irregular wave maker–hinged flap type, featuring active wave reflection compensation. An efficient real time algorithm has been selected to run the control system device. The system is able to generate first order irregular waves and detect reflected waves that approach the wave maker by means of wave probes mounted on the face of the flap. The probe registers the input data to be used by the actuator to compensate the incoming wave by controlling the flap motion. Computer simulations obtained for a wave-maker in a flume are used to demonstrate the efficiency of each step of the theory and the overall accuracy of the compensation system.

Research of the Servo Motion Control of Wave Maker

2014 ◽  
Vol 541-542 ◽  
pp. 1243-1247
Author(s):  
Lin Fang Su ◽  
Ai Feng Zhang ◽  
Xiao Liang
Keyword(s):  
Motion Control ◽  
Practical Significance ◽  
Stable Operation ◽  
Wave System ◽  
Servo Motor ◽  
Irregular Wave ◽  
Wave Flume ◽  
Function Modules ◽  
Wave Maker ◽  
First Time

This paper expatiated a system that was irregular wave maker in wave flume. It was the first time to apply ROCKWELL companys products and motion control technology into the wave-maker system. Firstly, We designed a series of function modules for control system. Then gave the relevant programming flowchart. Secondly, we intruduced the ROCKWELLs softlogix5800 series controller and Ultra3000 series driver in the application of make-wave system. Finally, the system had been successfully applied to the test of scientific research.Compared with the method of simulation control , this servo motor-driven irregular wave machine system have high precision, stable operation, wiring simple. Generally speaking, it provides the practical significance with certain practical foundation and experience for future projects.

Computational Fluid Dynamics Reproduction of Nonlinear Loads on a Vertical Column During Extreme Irregular Wave Events

2018 ◽  
Vol 140 (6) ◽  
Author(s):  
Erin E. Bachynski ◽  
Csaba Pákozdi ◽  
Anders Östman ◽  
Carl Trygve Stansberg
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Vertical Cylinder ◽  
Test Case ◽  
Wave Loads ◽  
Reconstruction Procedure ◽  
Vertical Column ◽  
Irregular Wave ◽  
Wave Maker ◽  
The Waves

Recently, a method for numerical reproduction of measured irregular wave events has been developed. The measured motion of the wave maker flaps defines the wave kinematics at the boundary of the numerical simulation in order to generate the waves. When such data are not available, the control signal of the wave maker can, instead, be generated from a given free surface elevation following the same procedure as in model tests. This procedure is applied to a model test case with extreme irregular wave events and resulting nonlinear global wave loads on a vertical cylinder, focusing on higher-order ringing excitation. The purpose of the investigation is twofold: (1) to validate the wave reconstruction procedure and (2) to validate the resulting computational fluid dynamics (CFD) ringing loads with the given waves. In order to better understand the frequency content in the CFD-generated loads, wavelet analysis as well as the response of a single degree-of-freedom (SDOF) oscillator is examined and compared with the corresponding results for the third-order wave forcing based on the MacCamy–Fuchs (MF) and Faltinsen, Newman, Vinje (FNV) formulations. The results show generally good agreement between CFD and experiment both in the waves and in the loads; discrepancies found in the loads mainly originate from corresponding uncertainties in the wave reconstruction. Wave breaking may be one source of uncertainty. The MF + FNV formulation showed reasonable prediction of the maximum responses of an SDOF oscillator, but could not capture the loads well at all of the important frequencies.

CFD Reproduction of Model Test Generated Extreme Irregular Wave Events and Nonlinear Loads on a Vertical Column

2016 ◽  
Author(s):  
Csaba Pakozdi ◽  
Anders Östman ◽  
Erin E. Bachynski ◽  
Carl Trygve Stansberg
Keyword(s):  
Model Test ◽  
Vertical Cylinder ◽  
Control Signal ◽  
Test Case ◽  
Wave Loads ◽  
Reconstruction Procedure ◽  
Vertical Column ◽  
Irregular Wave ◽  
Wave Maker ◽  
The Waves

Recently, a method for numerical reproduction of measured irregular wave events has been developed. The measured motion of the wave maker flaps defines the wave kinematics at the boundary of the numerical simulation in order to generate the waves as described in (Pakozdi, Kendon, & Stansberg, 2011) and (Ostman, Pakozdi, Stansberg, Fagertun, & Vestbostad, 2015). When such data are not available, the control signal of the wave maker can, instead, be generated from a given free surface elevation following the same procedure as in model tests. Following this procedure automatically gives the possibility to subsequently reproduce the numerical wave experimentally using the obtained control signal. The latter procedure is applied to a model test case with extreme irregular wave events and resulting nonlinear global wave loads on a vertical cylinder (Stansberg, 1997), with the focus on higher-order ringing excitation. The purpose of the investigation is two-fold: 1) to validate the wave reconstruction procedure, and 2) to validate the resulting CFD ringing loads with the given waves. The results show generally good agreement both in the waves and in the loads; discrepancies found in the loads are considered to be mainly originating from corresponding uncertainties in the wave reconstruction. Wave breaking may be one source of uncertainty.

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