A time‐domain numerical model for the acoustic scattering from rigid or elastic targets

1999 ◽  
Vol 105 (2) ◽  
pp. 1225-1225
Author(s):  
Ahmed El‐Ghaouty ◽  
Bertrand Dubus ◽  
Antoine Lavie
Keyword(s):  
Numerical Model ◽  
Time Domain ◽  
Acoustic Scattering

Calibration of a Time-Domain Hydrodynamic Model for A 12 MW Semi-Submersible Floating Wind Turbine

2021 ◽  
Author(s):  
Carlos Eduardo Silva de Souza ◽  
Nuno Fonseca ◽  
Petter Andreas Berthelsen ◽  
Maxime Thys
Keyword(s):  
Numerical Model ◽  
Wind Turbine ◽  
Time Domain ◽  
Quadratic Model ◽  
Wave Loads ◽  
Frequency Wave ◽  
Load Models ◽  
Wave Drift ◽  
Floating Wind Turbine ◽  
Decay Tests

Abstract Design optimization of mooring systems is an important step towards the reduction of costs for the floating wind turbine (FWT) industry. Accurate prediction of slowly-varying horizontal motions is needed, but there are still questions regarding the most adequate models for low-frequency wave excitation, and damping, for typical FWT concepts. To fill this gap, it is fundamental to compare existing load models against model tests results. This paper describes a calibration procedure for a three-columns semi-submersible FWT, based on adjustment of a time-domain numerical model to experimental results in decay tests, and tests in waves. First, the numerical model and underlying assumptions are introduced. The model is then validated against experimental data, such that the adequate load models are chosen and adjusted. In this step, Newman’s approximation is adopted for the second-order wave loads, using wave drift coefficients obtained from the experiments. Calm-water viscous damping is represented as a linear and quadratic model, and adjusted based on decay tests. Additional damping from waves is then adjusted for each sea state, consisting of a combination of a wave drift damping component, and one component with viscous nature. Finally, a parameterization procedure is proposed for generalizing the results to sea states not considered in the tests.

Experimentally calibrated simplified time-domain numerical model for a multi-chamber OWC device

2015 ◽  
pp. 463-469
Author(s):  
A Iturrioz ◽  
J Sarmiento ◽  
J Armesto ◽  
R Guanche ◽  
C Vidal ◽  
...  
Keyword(s):  
Numerical Model ◽  
Time Domain

Numerical Model of Towing Line in Sea Transport

2014 ◽  
Author(s):  
Ivan Ćatipović ◽  
Nastia Degiuli ◽  
Andreja Werner ◽  
Većeslav Čorić ◽  
Jadranka Radanović
Keyword(s):  
Numerical Model ◽  
Time Domain ◽  
Degrees Of Freedom ◽  
Vertical Plane ◽  
Cost Effective ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Sea Transport ◽  
Nonlinear Properties ◽  
Wave Induced

Towing as a specific type of sea transport is often used for installing objects for drilling and exploitation of underwater gas and oil wells. Also, towing proved to be a cost-effective solution for the installation of the offshore wind turbine electric generators at sea locations. Because of the mass of these objects the need for towing increases progressively. Time domain numerical model for the wave-induced motions of a towed ship and the towline tension in regular head seas is presented in this paper. For the sake of simplicity, one end of the towing line is attached to ship’s bow and another end has prescribed straight line motion. All considerations are done in the vertical plane so the ship is modeled as a rigid body with three degrees of freedom. Hydrodynamic loadings due to waves are taken into account along with added mass and damping. Dynamics of the towing line is described by finite elements. Due to the nonlinear properties of the problem calculations are done in time domain. Comparison of the obtained numerical results is made with previously published results.

Broadband monostatic acoustic scattering simulations of underwater unexploded ordnance using time-domain spectral-elements

2019 ◽  
Vol 146 (4) ◽  
pp. 3005-3005
Author(s):  
Alexis Bottero ◽  
Earl G. Williams ◽  
William A. Kuperman ◽  
Sandrine Rakotonarivo
Keyword(s):  
Time Domain ◽  
Acoustic Scattering ◽  
Spectral Elements ◽  
Unexploded Ordnance
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