Numerical investigation of harbor oscillations induced by focused transient wave groups

2020 ◽  
Vol 158 ◽  
pp. 103670 ◽  
Author(s):  
Junliang Gao ◽  
Xiaozhou Ma ◽  
Jun Zang ◽  
Guohai Dong ◽  
Xiaojian Ma ◽  
...  
2021 ◽  
Vol 911 ◽  
Author(s):  
L.F. Chen ◽  
P.H. Taylor ◽  
D.Z. Ning ◽  
P.W. Cong ◽  
H. Wolgamot ◽  
...  
Keyword(s):  

Abstract


2020 ◽  
pp. 103838
Author(s):  
Zhenjun Zheng ◽  
Xiaozhou Ma ◽  
Yuxiang Ma ◽  
Marc Perlin ◽  
Guohai Dong

2017 ◽  
Vol 125 ◽  
pp. 119-131 ◽  
Author(s):  
Junliang Gao ◽  
Chunyan Ji ◽  
Oleg Gaidai ◽  
Yingyi Liu ◽  
Xiaojian Ma

Author(s):  
O̸ystein Lande ◽  
Thomas B. Johannessen

Analysis of wave structure interaction problems are increasingly handled by employing CFD methods such as the well known Volume-of-Fluid (VoF) method. In particular for the problem of deck impact on fixed structures with slender substructures, CFD methods have been used extensively in the last few years. For this case, the initial conditions have usually been treated as regular waves in an undisturbed wave field which may be given accurately as input. As CFD analyses become more widely available and are used for more complex problems it is also necessary to consider the problem of irregular waves in a CFD context. Irregular waves provide a closer description of the sea surface than regular waves and are also the chief source of statistical variability in the wave induced loading level. In general, it is not feasible to run a long simulation of an irregular seastate in a CFD analysis today since this would require very long simulation times and also a very large computational domain and sophisticated absorbing boundary conditions to avoid build-up of reflections in the domain. The present paper is concerned with the use of a single transient wave group to represent a large event in an irregular wave group. It is well known that the autocovariance function of the wave spectrum is proportional to the mean shape of a large wave in a Gaussian wave field. The transient nature of such a wave ensures that a relatively small wave is generated at the upwave boundary and dissipated at the downwave boundary compared with the wave in the centre of the domain. Furthermore, a transient wave may be embedded in a random background if it is believed that the random background is important for the load level. The present paper describes the method of generating transient wave groups in a CFD analysis of wave in deck impact. The evolution of transient wave groups is first studied and compared with experimental measurements in order to verify that nonlinear transient waves can be calculated accurately using the present CFD code. Vertical wave induced loads on a large deck is then investigated for different undisturbed wave velocities and deck inundations.


Author(s):  
Christian Schmittner ◽  
Joris Brouwer ◽  
Janou Hennig

For hydrodynamic model testing different types of model waves are applied, where the most common ones are regular (monochromatic) and irregular (multichromatic) waves. In addition to these wave types the application of focusing wave groups, which are also often denoted as wave packages or transient wave packets, can give insight into aspects that cannot be assessed by the conventional model waves. This paper describes the different applications of focusing wave groups for hydrodynamic model testing. The paper starts with the historical background, followed by a theoretical description and the generation procedure. The main part of the paper is dedicated to the practical application of focusing wave groups in the basin. Items that will be described are a) the derivation of transfer functions for floating structures and for anti-roll tanks b) the determination of hydraulic and electrical transfer function of wave makers c) the verification of position and calibration of wave probes in the basin d) the generation of extreme wave events e) the assessment of reflection coefficient of beaches f) the investigation of non-linear aspects of transfer functions. Finally, characteristics of the analysis of focusing waves are introduced and compared to conventional methods based on regular and irregular waves.


2020 ◽  
Vol 70 (6) ◽  
pp. 845-845
Author(s):  
Xiaozhou Ma ◽  
Zhenjun Zheng ◽  
Xiang Zhang ◽  
Guohai Dong

Author(s):  
Hongchao Wang ◽  
Scott Draper ◽  
Wenhua Zhao ◽  
Hugh Wolgamot ◽  
Liang Cheng

This paper addresses the process of establishing a numerical model to accurately reproduce experimental results presented by Zhao et al. (2017) of three-dimensional (3D) gap resonance between two fixed ship-shaped boxes. The ship-shaped boxes were arranged in a side-by-side configuration to represent FLNG offloading and were subjected to NewWave-type transient wave groups. To develop the numerical model we employ the open-source Computational Fluid Dynamics (CFD) package OpenFOAM and systematically optimize mesh topology and size, domain size and boundary conditions. CFD is necessary for this problem to accurately reproduce the viscous losses and non-linear free surface effects that are observed in the experiments. The incident transient wave group used in the experiment is regenerated using various iterative schemes. The results show satisfactory agreements between the target and regenerated waves.


2019 ◽  
Vol 70 (1) ◽  
pp. 1-19 ◽  
Author(s):  
Xiouzhou Ma ◽  
Zhenjun Zheng ◽  
Xiang Zhang ◽  
Guohai Dong

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