Application of Boundary Element Method for Determination of the Wavemaker Driving Signal

2018 ◽  
Author(s):  
Anatoliy Khait ◽  
Lev Shemer
Keyword(s):  
Boundary Element Method ◽  
Boundary Element ◽  
Wave Train ◽  
Amplitude Spectrum ◽  
Surface Elevation ◽  
Wave Tank ◽  
Amplitude Spectra ◽  
Wave Trains ◽  
Driving Signal ◽  
Element Method

Excitation of steep unidirectional broad-banded wave trains is studied numerically and experimentally. Iterative method is developed to adjust the driving signal of a paddle-type wavemaker to generate wave train with a prescribed free waves’ spectrum. Analytical post-processing procedure based on the Zakharov equation is applied to separate complex amplitude spectrum of the surface elevation into free and bound components, as required for the proposed method of the adjustment of the wavemaker driving signal. Numerical wave tank in the simulations was based on application of the Boundary Element Method. The results of numerical simulations were supported by measurements in a wave tank. The measured and the designed shapes of the surface elevation variation with time, as well as of the corresponding amplitude spectra were found to be in a good agreement.

Application of Boundary Element Method for Determination of the Wavemaker Driving Signal

2019 ◽  
Vol 141 (6) ◽  
Author(s):  
Anatoliy Khait ◽  
Lev Shemer
Keyword(s):  
Boundary Element Method ◽  
Boundary Element ◽  
Wave Train ◽  
Amplitude Spectrum ◽  
Second Order ◽  
Surface Elevation ◽  
Frequency Spectra ◽  
Wave Tank ◽  
Driving Signal ◽  
Element Method

A method for the generation of steep nonlinear broad-banded wave trains having an arbitrary prescribed shape is developed. It is shown that the second-order contributions to the velocity field are negligible in deep water, while the second-order bound components of the surface elevation are significant. This fact allows improvement of an iterative method of the wavemaker driving signal adjustment that increases the accuracy of excitation of wave train with the prescribed free waves’ spectrum. The decomposition of the complex amplitude spectrum of the surface elevation into free and bound components is based on the approach adopted in the derivation of the Zakharov model. The iterative adjustment of the driving signal is carried out using the numerical wave tank based on the boundary element method. It is demonstrated that accurate wave train excitation is attained for different values of the wave steepness. The method allows decreasing the number of iterations needed for the driving signal adjustment. The surface elevation values measured in the laboratory wave tank agree closely with those obtained in the numerical simulations. The measured and the simulated frequency spectra are in agreement as well.

scholarly journals 2-D Numerical Wave Tank by Boundary Element Method Using Different Numerical Techniques

2013 ◽  
Vol 1 (1) ◽  
Author(s):  
Farid Habashi Aliabadi ◽  
Parviz Ghadimi ◽  
Seyed Reza Djeddi ◽  
Abbas Dashtimanesh
Keyword(s):  
Boundary Element Method ◽  
Boundary Element ◽  
Numerical Wave Tank ◽  
Numerical Techniques ◽  
Wave Tank ◽  
Numerical Wave ◽  
Element Method

Green Water Loads on a Cruise Ship

2013 ◽  
Author(s):  
Jens Ley ◽  
Jan Oberhagemann ◽  
Christoph Amian ◽  
Markus Langer ◽  
Vladimir Shigunov ◽  
...  
Keyword(s):  
Boundary Element Method ◽  
Boundary Element ◽  
Bridge Deck ◽  
Green Water ◽  
Medium Size ◽  
Front Wall ◽  
Cruise Ship ◽  
Wave Trains ◽  
Element Method

A linear boundary-element method and a Reynolds-averaged Navier-Stokes (RANS) equations solver were combined to predict maximum green water loads on a typical cruise ship of medium size. For structural analysis, a one-way coupling mapped the hydrodynamic pressure from the finite-volume grid onto the computational structural dynamics finite element mesh. First, linear long-term maximum ship responses were determined by a boundary element method combined with long-term statistics based on spectral methods; transfer functions of these responses were used to define response-conditioned wave trains inducing the linear long-term maximum ship response. The investigated wave sequences were correlated to a dedicated probability level for a lifecycle time of 20 years in the North Atlantic environmental wave conditions and for a ship speed of six knots. Critical impact locations were found to include the weather deck in the foreship, the front wall of the superstructure and the overhanging bridge deck. Predicted loads were compared to experimental data obtained in conditioned wave trains and in extreme irregular sea states. Numerical and experimental results revealed significantly higher loads than design loads specified by classification society rules. Pressure peaks on the weather deck and the superstructure front wall were comparable to rule-based design pressures for breakwaters on containerships and exceeded pressure peaks on the bridge deck.

A BOUNDARY-ELEMENT METHOD FOR ATOMIZATION OF A FINITE LIQUID JET

1995 ◽  
Vol 5 (6) ◽  
pp. 621-638 ◽  
Author(s):  
J. H. Hilbing ◽  
Stephen D. Heister ◽  
C. A. Spangler
Keyword(s):  
Boundary Element Method ◽  
Boundary Element ◽  
Liquid Jet ◽  
Element Method

Application of the Boundary Element Method and Modal Analysis to Tire Acoustics Problems

1993 ◽  
Vol 21 (2) ◽  
pp. 66-90 ◽  
Author(s):  
Y. Nakajima ◽  
Y. Inoue ◽  
H. Ogawa
Keyword(s):  
Finite Element ◽  
Boundary Element Method ◽  
Boundary Element ◽  
Acoustic Radiation ◽  
Traffic Noise ◽  
Noise Prediction ◽  
Prediction System ◽  
Tire Noise ◽  
Acoustic Contribution ◽  
Element Method

Abstract Road traffic noise needs to be reduced, because traffic volume is increasing every year. The noise generated from a tire is becoming one of the dominant sources in the total traffic noise because the engine noise is constantly being reduced by the vehicle manufacturers. Although the acoustic intensity measurement technology has been enhanced by the recent developments in digital measurement techniques, repetitive measurements are necessary to find effective ways for noise control. Hence, a simulation method to predict generated noise is required to replace the time-consuming experiments. The boundary element method (BEM) is applied to predict the acoustic radiation caused by the vibration of a tire sidewall and a tire noise prediction system is developed. The BEM requires the geometry and the modal characteristics of a tire which are provided by an experiment or the finite element method (FEM). Since the finite element procedure is applied to the prediction of modal characteristics in a tire noise prediction system, the acoustic pressure can be predicted without any measurements. Furthermore, the acoustic contribution analysis obtained from the post-processing of the predicted results is very helpful to know where and how the design change affects the acoustic radiation. The predictability of this system is verified by measurements and the acoustic contribution analysis is applied to tire noise control.

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