Numerical Simulation and Analysis of Phase Focused Breaking and Non-Breaking Wave Impact on Fixed Offshore Platform Deck

2019 ◽  
Author(s):  
Rameeza Moideen ◽  
Manasa Ranjan Behera ◽  
Arun Kamath ◽  
Hans Bihs
Keyword(s):  
Impact Force ◽  
Experimental Results ◽  
Breaking Wave ◽  
Numerical Wave Tank ◽  
Wave Impact ◽  
Wave Heights ◽  
Numerical Wave ◽  
Focused Wave ◽  
The Impact ◽  
Vertical Impact

Abstract Extreme wave impact due to tsunamis and storm surge create large wave heights causing destruction to coastal and offshore structures. These extreme waves are represented by focused waves in the present study and the impact on offshore deck is studied. Numerical wave tank used is modelled using open-source software REE3D, where the level set method is used to capture the air-water interface. Vertical impact force on offshore deck is computed and compared with the experimental results to validate the numerical model. Focused wave is generated by phase focusing a group of waves at a particular position and time. The nonlinearity of focused wave and its effect on the vertical impact force is quantified for different airgap and increasing wave heights. The steepness of this focused wave is increased to initiate phase focused breaking in the numerical wave tank, which is validated with experimental results of Ghadirian et al., 2016. The main purpose of this paper is to examine breaking focused wave group loads on the offshore deck and to study the impact on deck at different breaking locations. The positioning of the deck with respect to breaker location have shown that the maximum horizontal impact force due to breaking wave occurs when the plunging crest hits the deck side.

scholarly journals Effect of Girder Spacing and Depth on the Solitary Wave Impact on Coastal Bridge Deck for Different Airgaps

2019 ◽  
Vol 7 (5) ◽  
pp. 140 ◽  
Author(s):  
Rameeza Moideen ◽  
Manasa Ranjan Behera ◽  
Arun Kamath ◽  
Hans Bihs
Keyword(s):  
Solitary Wave ◽  
Bridge Deck ◽  
Impact Force ◽  
Storm Surges ◽  
Wave Impact ◽  
Wave Condition ◽  
Bridge Damage ◽  
Wave Heights ◽  
The Impact ◽  
Vertical Impact

Coastal bridge damage has become a severe issue of concern in the recent past with the destruction of a considerable number of bridges under the impact of waves during tsunami and storm surges. These events have become more frequent, with waves reaching the bridge deck and causing upliftment and destruction. Past studies have demonstrated the establishment of various theoretical equations which works well for the submerged deck and regular wave types but show much scatter and uncertainty in case of a deck that is above still water level (SWL). The present study aims to generate a solitary wave to represent an extreme wave condition like a tsunami in the numerical wave tank modeled using the open source computational fluid dynamics (CFD) model REEF3D and to study the vertical impact force on the coastal bridge deck. A parametric study is carried out for increasing wave heights, girders spacing and depth for varying airgaps to analyze the effect of these parameters on the peak vertical impact force. It is observed that increasing the girder spacing and girder depth is effective in reducing the peak vertical impact force for the cases considered.

Numerical Simulation and Analysis of Phase-Focused Breaking and Non-Breaking Wave Impact on a Fixed Offshore Platform Deck

2020 ◽  
Vol 142 (5) ◽  
Author(s):  
Rameeza Moideen ◽  
Manasa Ranjan Behera ◽  
Arun Kamath ◽  
Hans Bihs
Keyword(s):  
Open Source Software ◽  
Impact Force ◽  
Offshore Structures ◽  
Breaking Wave ◽  
Wave Impact ◽  
Large Wave ◽  
Air Water Interface ◽  
Wave Heights ◽  
Fixed Offshore Platform ◽  
Vertical Impact

Abstract Extreme wave impact due to tsunamis and storm surge create large wave heights that cause destruction to coastal and offshore structures. Focused waves have been used to represent such extreme waves, and in the present study, its impact on offshore deck has been studied numerically. Numerical modeling has been carried out using open-source software reef3d, with the level set method to capture the air–water interface. Focused waves are generated by phase focusing a group of waves at a particular position and time. The nonlinearity of focused waves and its effect on the vertical impact force has been quantified for different airgaps and increasing wave heights. The wave steepness was increased to initiate phase-focused breaking in the numerical wave tank, which was then validated with the experimental results. This breaking-focused wave impact on offshore deck is then studied at different breaking locations. The results for different positionings of the deck with respect to breaker location show that the maximum horizontal impact force on the deck occurs when the plunging crest hits the deck side.

Numerical Investigation of Focused Waves and Their Interaction With a Vertical Cylinder Using REEF3D

2017 ◽  
Vol 139 (4) ◽  
Author(s):  
Hans Bihs ◽  
Mayilvahanan Alagan Chella ◽  
Arun Kamath ◽  
Øivind Asgeir Arntsen
Keyword(s):  
Free Surface ◽  
Stokes Equations ◽  
Free Surface Flows ◽  
Surface Elevation ◽  
Numerical Wave Tank ◽  
Free Surface Elevation ◽  
Wave Tank ◽  
Numerical Wave ◽  
Focused Wave ◽  
The Impact

For the stability of offshore structures, such as offshore wind foundations, extreme wave conditions need to be taken into account. Waves from extreme events are critical from the design perspective. In a numerical wave tank, extreme waves can be modeled using focused waves. Here, linear waves are generated from a wave spectrum. The wave crests of the generated waves coincide at a preselected location and time. Focused wave generation is implemented in the numerical wave tank module of REEF3D, which has been extensively and successfully tested for various wave hydrodynamics and wave–structure interaction problems in particular and for free surface flows in general. The open-source computational fluid dynamics (CFD) code REEF3D solves the three-dimensional Navier–Stokes equations on a staggered Cartesian grid. Higher order numerical schemes are used for time and spatial discretization. For the interface capturing, the level set method is selected. In order to test the generated waves, the time series of the free surface elevation are compared with experimental benchmark cases. The numerically simulated free surface elevation shows good agreement with experimental data. In further computations, the impact of the focused waves on a vertical circular cylinder is investigated. A breaking focused wave is simulated and the associated kinematics is investigated. Free surface flow features during the interaction of nonbreaking focused waves with a cylinder and during the breaking process of a focused wave are also investigated along with the numerically captured free surface.

A Numerical Study of a Focused Wave Packet Near the Surf Zone

2012 ◽  
Author(s):  
Csaba Pakozdi ◽  
Timothy E. Kendon ◽  
Carl-Trygve Stansberg
Keyword(s):  
Wave Packet ◽  
Model Test ◽  
Surf Zone ◽  
Breaking Wave ◽  
Numerical Wave Tank ◽  
Wave Tank ◽  
Numerical Reconstruction ◽  
Numerical Wave ◽  
Focused Wave ◽  
Sloping Bottom

In this paper the numerical modeling of breaking waves propagating on a gently sloping bottom in shallow water is investigated. As more and more countries look to install offshore wind farms in their coastal waters, the breaking wave impact force on wind turbine foundations has been an area of increased research. For meaningful comparisons between measurement and simulation, the numerical reconstruction of the model test breaking wave event must be fairly exact. The combination of numerical reconstruction of model tests using computational fluid dynamics has proved a valuable tool to provide insight into the physics of the breaking wave phenomenon in deep water ([1]). To refine the technique of numerically reconstructing the breaking wave in shallow water, comparisons to a series of model tests with breaking wave events near the surf zone are made. The sloping bottom is modeled with a ramp with a gradient of 2.8 degrees in a wave tank. This paper describes the numerical reproduction of a focused wave packet, for studying its shoaling and breaking. The commercial CFD tool Star-CCM+ has been used to reproduce a measured focused wave packet train in a numerical wave tank. Its RANSE physical model with VOF technique is applied for this investigation. The numerical wave generation is based on the technique presented in [1], where the measured angle of the wave makers flap and the measured free surface elevation at the flap has been used to define a transient inlet condition for the simulation. In this paper, the numerically simulated wave elevation around the breaking point is compared with the measured time series. Promising results are obtained. The numerical model reproduces, at the same location and time, the breaking events as it was observed during the model test. One conclusion from this particular case is that the time step is critical; it should be very small during the breaking events which may result in a very long simulation time. Further work is suggested to meet this challenge, as well as for more refined studies to improve the complete numerical wave tank model.

scholarly journals Influence of the Spatial Pressure Distribution of Breaking Wave Loading on the Dynamic Response of Wolf Rock Lighthouse

2021 ◽  
Vol 9 (1) ◽  
pp. 55
Author(s):  
Darshana T. Dassanayake ◽  
Alessandro Antonini ◽  
Athanasios Pappas ◽  
Alison Raby ◽  
James Mark William Brownjohn ◽  
...  
Keyword(s):  
Dynamic Response ◽  
Pressure Distribution ◽  
Distinct Element ◽  
Breaking Waves ◽  
Breaking Wave ◽  
Wave Loading ◽  
Wave Impact ◽  
Pressure Distributions ◽  
Impact Area ◽  
The Impact

The survivability analysis of offshore rock lighthouses requires several assumptions of the pressure distribution due to the breaking wave loading (Raby et al. (2019), Antonini et al. (2019). Due to the peculiar bathymetries and topographies of rock pinnacles, there is no dedicated formula to properly quantify the loads induced by the breaking waves on offshore rock lighthouses. Wienke’s formula (Wienke and Oumeraci (2005) was used in this study to estimate the loads, even though it was not derived for breaking waves on offshore rock lighthouses, but rather for the breaking wave loading on offshore monopiles. However, a thorough sensitivity analysis of the effects of the assumed pressure distribution has never been performed. In this paper, by means of the Wolf Rock lighthouse distinct element model, we quantified the influence of the pressure distributions on the dynamic response of the lighthouse structure. Different pressure distributions were tested, while keeping the initial wave impact area and pressure integrated force unchanged, in order to quantify the effect of different pressure distribution patterns. The pressure distributions considered in this paper showed subtle differences in the overall dynamic structure responses; however, pressure distribution #3, based on published experimental data such as Tanimoto et al. (1986) and Zhou et al. (1991) gave the largest displacements. This scenario has a triangular pressure distribution with a peak at the centroid of the impact area, which then linearly decreases to zero at the top and bottom boundaries of the impact area. The azimuthal horizontal distribution was adopted from Wienke and Oumeraci’s work (2005). The main findings of this study will be of interest not only for the assessment of rock lighthouses but also for all the cylindrical structures built on rock pinnacles or rocky coastlines (with steep foreshore slopes) and exposed to harsh breaking wave loading.

scholarly journals Research and Improvement of the Hydraulic Suspension System for a Heavy Hydraulic Transport Vehicle

2020 ◽  
Vol 10 (15) ◽  
pp. 5220 ◽  
Author(s):  
Jianjun Wang ◽  
Jingyi Zhao ◽  
Wenlei Li ◽  
Xing Jia ◽  
Peng Wei
Keyword(s):  
Mathematical Model ◽  
Nonlinear System ◽  
Ride Comfort ◽  
Impact Force ◽  
Suspension System ◽  
Experimental Results ◽  
Hydraulic Transport ◽  
Transport Vehicle ◽  
Set Up ◽  
The Impact

In order to ensure the ride comfort of a hydraulic transport vehicle in transportation, it is important to account for the effects of the suspension system. In this paper, an improved hydraulic suspension system based on a reasonable setting of the accumulator was proposed for a heavy hydraulic transport vehicle. The hydraulic transport vehicle was a multi-degree nonlinear system, and the establishment of an appropriate vehicle dynamical model was the basis for the improvement of the hydraulic suspension system. The hydraulic suspension system was analyzed, and a mathematical model of the hydraulic suspension system with accumulator established and then analyzed. The results revealed that installing the appropriate accumulator can absorb the impact pressure on the vehicle, while a hydraulic suspension system with an accumulator can be designed. Further, it was proved that a reasonable setting for the accumulator can reduce the impact force on the transport vehicle through simulation, and the optimal accumulator parameters can be obtained. Finally, an experiment in the field was set up and carried out, and the experimental results presented to prove the viability of the proposed method.

Simulation of Wave Slamming on Open-Piled Structures Based on FLUENT

2012 ◽  
Vol 256-259 ◽  
pp. 1960-1964
Author(s):  
Feng Jin
Keyword(s):  
Experimental Data ◽  
Wave Height ◽  
Impact Pressure ◽  
Two Dimensional ◽  
Numerical Wave Tank ◽  
Regular Wave ◽  
Wave Impact ◽  
Wave Tank ◽  
Wave Slamming ◽  
Numerical Wave

In order to study the specialties of wave slamming on open-piled structures, a two-dimensional regular wave tank was established based on commercial CFD software FLUENT. Three typical cases of regular wave slamming on the open-piled structures were reproduced by using the numerical wave tank and compared with the experimental data available. Good agreements were obtained between the numerical and experimental results and the average of peak impact pressure was chosen as the characteristic impact pressure. Then regular wave impact pressure on the open-piled structures under various wave height, period and over height were simulated. The influences of the three parameters on the distribution of impact pressure were analyzed.

scholarly journals IMPULSIVE BREAKING WAVE FORCES ON AN INCLINED PILE EXERTED BI RANDOM WAVES

1986 ◽  
Vol 1 (20) ◽  
pp. 168 ◽  
Author(s):  
K. Tanimoto ◽  
S. Takahashi ◽  
T. Kaneko ◽  
K. Shiota
Keyword(s):  
Time History ◽  
Experimental Results ◽  
Wave Crest ◽  
Wave Forces ◽  
Breaking Wave ◽  
Force Parameter ◽  
Breaking Force ◽  
Large Wave ◽  
The Impact ◽  
Breaking Wave Forces

A calculation method of the impulsive breaking wave forces on piles is proposed in this paper. It is derived on the basis of experimental results with some theoretical considerations. Wave forces on a cylinder caused by both regular and irregular trains of waves are measured in a large wave flume. The experimental results are compared with the values predicted by both Wagner and Karman. In the proposed method, it is assumed that the impulsive force acts on the upper half of the pile between the still water level and the wave crest, and that the force distribution along the pile is triangular shape. The peak value in the distribution is expressed by the function of both the breaking force parameter and the inclination angle of the cylinder. The breaking force parameter is the ratio of the bottom slope to wave steepness. The time history of the impact force is given as a triangular pulse with a vertical rise. The duration time is determined as half of the value predicted by Karman's theory.

Size Effects in the Impact of Carbon Fiber Reinforced Composite Structures

2018 ◽  
Vol 789 ◽  
pp. 155-160
Author(s):  
Yi Ou Shen ◽  
Yan Li
Keyword(s):  
Size Effects ◽  
Composite Structures ◽  
Impact Force ◽  
Flexural Rigidity ◽  
Experimental Results ◽  
Target Size ◽  
Mass Model ◽  
Energy Impact ◽  
Maximum Impact Force ◽  
The Impact

In this study, target size effects in the low energy impact response of plain CFRP plateswere investigated. It was found that increase the target size leads to a reduction in the maximumimpact force recorded during the test. This is due to the reduction on flexural rigidity of the largerpanels. The experimental results indicated that at energies above the first failure threshold, themaximum impact force does not coincidence with the predicting value. Two mathematical modelswere used to predict the maximum impact force including single degree of freedom (SDOF)spring-mass model and Energy-Balance (E-B) model. The predicting results were then comparedwith the experimental results, and both of the two models show good agreement with theexperimental results in elastic deformation region. In addition, the level of agreement between thepredictions and the experimental results indicate that both models are capable of modelling theimpact response of these CFRP panels at elastic regime.

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