Spectral Analysis of Irregular Wave Impact on the Structure in Splash Zone

2002 ◽  
Author(s):  
Bing Ren ◽  
Yongxue Wang
Keyword(s):  
Spectral Analysis ◽  
Wave Height ◽  
Incident Wave ◽  
Impact Pressure ◽  
Splash Zone ◽  
Spectral Moment ◽  
Wave Impact ◽  
Large Wave ◽  
Irregular Wave ◽  
The Impact

The spectral analysis from experimental data of irregular wave impact on the structures with large dimension in the splash zone is presented. The experiments were conducted in the large wave-current tank in the State Key Laboratory of Coastal and Offshore Engineering, Dalian University of Technology. In the experiment, the target spectrum is JONSWAP spectrum, the significant wave height H1/3 is in the range from 0.1m to 0.3m, and the peak period of spectrum Tp in the range from 1.0s to 2.0s. The ratio of s/H1/3, which refers to the clearance of the subface of the structure above still water level (s) to the incident wave height, is between −0.1 and 0.4. The spectral analysis results of the irregular wave impact pressure on the subface of the structure under various case studies are presented. The distribution of spectral moment of the impact pressure on the structure along the subface is given. And the influence of different incident wave parameters and relative clearance s/H1/3 on the average spectral moment of impact pressure are discussed.

Numerical Simulations of Regular Wave Impact on Horizontal Plate Based on SPH Methods

2013 ◽  
Vol 353-356 ◽  
pp. 3531-3536
Author(s):  
Kun Zheng ◽  
Zhao Chen Sun ◽  
Chang Ping Chen ◽  
Feng Zhou
Keyword(s):  
Estimation Method ◽  
Impact Pressure ◽  
Horizontal Plate ◽  
Regular Waves ◽  
Wave Impact ◽  
Numerical Wave Flume ◽  
Wave Flume ◽  
Particle Hydrodynamics ◽  
Smoothed Particle ◽  
The Impact

The numerical wave flume was established for simulating the impact effects of regular waves on horizontal plate by adopting the method of Smoothed Particle Hydrodynamics (SPH).The impact process of regular waves on horizontal plate was analyzed, and the impact pressure-time curves were gotten using a new estimation method. The comparison of numerical results and experimental results shows that the new estimation method can predict the peak impact pressure more accurately.

scholarly journals A numerical study of tsunami wave impact and run-up on coastal cliffs using a CIP-based model

2017 ◽  
Vol 17 (5) ◽  
pp. 641-655 ◽  
Author(s):  
Xizeng Zhao ◽  
Yong Chen ◽  
Zhenhua Huang ◽  
Zijun Hu ◽  
Yangyang Gao
Keyword(s):  
Incident Wave ◽  
Tsunami Wave ◽  
Critical Value ◽  
Tsunami Source ◽  
Solid Boundary ◽  
Wave Impact ◽  
Submarine Slope ◽  
Coastal Cliffs ◽  
Run Up ◽  
The Impact

Abstract. There is a general lack of understanding of tsunami wave interaction with complex geographies, especially the process of inundation. Numerical simulations are performed to understand the effects of several factors on tsunami wave impact and run-up in the presence of gentle submarine slopes and coastal cliffs, using an in-house code, a constrained interpolation profile (CIP)-based model. The model employs a high-order finite difference method, the CIP method, as the flow solver; utilizes a VOF-type method, the tangent of hyperbola for interface capturing/slope weighting (THINC/SW) scheme, to capture the free surface; and treats the solid boundary by an immersed boundary method. A series of incident waves are arranged to interact with varying coastal geographies. Numerical results are compared with experimental data and good agreement is obtained. The influences of gentle submarine slope, coastal cliff and incident wave height are discussed. It is found that the tsunami amplification factor varying with incident wave is affected by gradient of cliff slope, and the critical value is about 45°. The run-up on a toe-erosion cliff is smaller than that on a normal cliff. The run-up is also related to the length of a gentle submarine slope with a critical value of about 2.292 m in the present model for most cases. The impact pressure on the cliff is extremely large and concentrated, and the backflow effect is non-negligible. Results of our work are highly precise and helpful in inverting tsunami source and forecasting disaster.

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 ANALYSIS OF FLUID FLOW IMPACT OSCILLATORY PRESSURES WITH AIR ENTRAPMENT AT STRUCTURES

2017 ◽  
pp. 31 ◽  
Author(s):  
Robert Brian Mayon ◽  
Zoheir Sabeur ◽  
Mingyi Tan ◽  
Kamal Djidjeli
Keyword(s):  
Fluid Flow ◽  
Numerical Model ◽  
Air Entrainment ◽  
Pressure Effects ◽  
Impact Pressure ◽  
Wave Loading ◽  
Air Entrapment ◽  
Wave Impact ◽  
Hydrodynamic Wave ◽  
The Impact

Hydrodynamic wave loading at coastal structures is a complex phenomenon to quantify. The chaotic nature of the fluid flow field as waves break against such structures has presented many challenges to Scientists and Engineers for the design of coastal defences. The provision of installations such as breakwaters to resist wave loading and protect coastal areas has evolved predominantly through empirical and experimental observations. This is due to the challenging understanding and quantification of wave impact energy transfer processes with air entrainment at these structures. This paper presents a numerical investigation on wave loading at porous formations including the effects of air entrapment. Porous morphologies generated from cubic packed spheres with varying characteristics representing a breakwater structure are incorporated into the numerical model at the impact interface and the effect on the pressure field is investigated as the wave breaks. We focus on analysing the impulse impact pressure as a surging flow front impacts a porous wall. Thereafter we investigate the multi-modal oscillatory wave impact pressure signals which result from a transient plunging breaker wave impinging upon a modelled porous coastal protective structure. The high frequency oscillatory pressure effects resulting from air entrapment are clearly observed in the simulations. A frequency domain analysis of the impact pressure responses is undertaken. We show that the structural morphology of the porous assembly influences the pressure response signal recorded during the impact event. The findings provide good confidence on the robustness of our numerical model particularly for investigating the air bubbles formation and their mechanics at impact with porous walls.

scholarly journals The Downscaling Study for Typhoon-Induced Coastal Inundation

Water ◽  
2020 ◽  
Vol 12 (4) ◽  
pp. 1103 ◽  
Author(s):  
Dongmin Jang ◽  
Wonkyun Joo ◽  
Chang-Hoo Jeong ◽  
Wonsu Kim ◽  
Sung Park ◽  
...  
Keyword(s):  
South Korea ◽  
Wave Height ◽  
Coastal Area ◽  
Numerical Models ◽  
High Tide ◽  
Storm Tide ◽  
Coastal Inundation ◽  
Irregular Wave ◽  
Coastal Cities ◽  
The Impact

Typhoons can often cause inundation in lower coastal cities by inducing strong surges and waves. Being affected by typhoon annually, the coastal cities in South Korea are very vulnerable to typhoons. In 2016, a typhoon ‘CHABA’, with a maximum 10 min sustained wind speed of about 50 m/s and a minimum central pressure of 905 hPa, hit South Korea, suffering tremendous damage. In particular, ‘CHABA’-induced coastal inundation resulted in serious damage to the coastal area of Busan where a lot of high-rise buildings and residential areas are concentrated, and was caused by the combined effect of tide, surge, and wave. The typhoon-induced surge raised sea levels during high tide, and the strong wave with a long period of more than 10 s eventually led to the coastal inundation at the same time. The present research focuses a numerical downscaling considering the effects of tide, surge and wave for coastal inundation induced by Typhoon ‘CHABA’. This downscaling approach applied several numerical models, which are the Weather Research and Forecasting model (WRF) for typhoon simulation, the Finite Volume Community Ocean Model (FVCOM) for tide and surge simulation, and the Simulating WAve Nearshore (SWAN) for wave simulation. In a domain covering the Korean Peninsula, typhoon-induced surges and waves were simulated applying the results simulated by WRF as meteorological conditions. In the downscaled domain ranged near the coastal area of Busan, the coastal inundation was simulated blending a storm tide height and an irregular wave height obtained from the domain, in which each height has 1 s interval. The irregular wave height was calculated using the significant wave height and peak period. Through this downscaling study, the impact of storm tide and wave on coastal inundation was estimated.

Underdeck Wave Slamming Model Tests for a Drilling Semi-Submersible Unit

2021 ◽  
Author(s):  
Lixin Xu ◽  
Xiaoqing Teng ◽  
Jinguang Wang ◽  
Sing-Kwan Lee ◽  
Jiancheng Liu ◽  
...  
Keyword(s):  
Wave Height ◽  
Significant Wave Height ◽  
Impact Pressure ◽  
Wave Impact ◽  
Significant Wave ◽  
Wave Basin ◽  
Slamming Load ◽  
Wave Slamming ◽  
Order Of Magnitude ◽  
Vertical Impact

Abstract Negative air gap and wave slamming load on the deck box of drilling semi-submersible units in severe storm have received a great deal of attention, due to the COSL Innovator accident in 2015. Equally important is vertical slamming load on the MODU underdeck, which is less reported in the literature. The present paper attempts to derive characteristic vertical slamming pressure on the deck bottom, based on an extensive model test program for a drilling semi-submersible unit, CM-SD1000. A total of 96 3-hour wave impact tests were conducted including 4 sea states selected along the DNV steepness criterion curve in 3 wave headings. Two critical sea states were identified and each was tested with 16 random realizations in both the head and the beam waves. 8 force panels were installed on the under-deck to capture vertical wave impact events. It is found that the peak slamming pressures obtained can be fitted well with both Weibull and Gumbel probability function. The extreme vertical impact pressure predicted are of the same order of magnitude as the extreme horizontal impact pressure. The present study also shows that rise velocities of the wave surface relative to the deck bottom have a remarkable correlation with the wave slamming pressure in terms of probability distribution. The relative rise velocities can be properly derived from wave probe measurements. This offers an alternative approach to estimate the vertical impact pressure without resort to force panels. In contrast to horizontal wave slamming, the magnitude and frequency of vertical ones simply increases with significant wave height and wave steepness has much less effect. It is found that the extreme vertical impact pressure can be approximated well by a linear function of the significant wave height. The linear relationship, if validated by more tests, may help evaluate structural strength of the deck bottom before wave basin model testing.

Physical and Numerical Investigations on Wave Run-Up and Dissipation under Breakwater with Fence Revetment

2021 ◽  
Vol 9 (12) ◽  
pp. 1355
Author(s):  
Enjin Zhao ◽  
Lin Mu ◽  
Zhaoyang Hu ◽  
Xinqiang Wang ◽  
Junkai Sun ◽  
...  
Keyword(s):  
Wave Height ◽  
Water Depth ◽  
Significant Wave Height ◽  
Irregular Waves ◽  
Structure Stability ◽  
Wave Impact ◽  
Significant Wave ◽  
Tide Level ◽  
Run Up ◽  
The Impact

Revetment elements and protective facilities on a breakwater can effectively weaken the impact of waves. In order to resist storm surges, there is a plan to build a breakwater on the northern shore of Meizhou Bay in Putian City, China. To better design it, considering different environmental conditions, physical and numerical experiments were carried out to accurately study the effects of the breakwater and its auxiliary structures on wave propagation. In the experiments, the influence of the wave type, initial water depth, and the structure of the fence plate are considered. The wave run-up and dissipation, the wave overtopping volume, and the structure stability are analyzed. The results indicate that the breakwater can effectively resist the wave impact, reduce the wave run-up and overtopping, and protect the rear buildings. In addition, under the same still water depth and significant wave height, the amount of overtopped water under regular waves is larger than that under irregular waves. With the increase of the still water depth and significant wave height, the overtopped water increases, which means that when the storm surge occurs, damage on the breakwater under the high tide level is greater than that under the low tide level. Besides, the fence plate can effectively dissipate energy and reduce the overtopping volume by generating eddy current in the cavity. Considering the stability and the energy dissipation capacity of the fence plate, it is suggested that a gap ratio of 50% is reasonable.

Performance Analysis of a Semicircular Free Surface Ocean Structure under the Different Water Depths

2011 ◽  
Vol 90-93 ◽  
pp. 2782-2789
Author(s):  
Gang Jun Zhai ◽  
Zhe Ma ◽  
Hee Min Teh ◽  
Vengatesan Venugopal
Keyword(s):  
Free Surface ◽  
Wave Height ◽  
Incident Wave ◽  
Wave Attenuation ◽  
Hydrodynamic Characteristics ◽  
Irregular Wave ◽  
Surface Ocean ◽  
Semicircular Breakwater ◽  
Water Depths ◽  
Structure Width

The increasing importance of the sustainability challenge in o engineering has led to the development of free surface ocean structure of various configurations. In this study, the hydrodynamic characteristics of a perforated free surface, semicircular breakwater (SCB) are investigated for irregular wave conditions under the different water depths. The performance of the breakwaters was evaluated in the form of coefficients of transmission (CT), reflection (CR) and energy dissipation (CL). The measured wave modification in front of the structure and in the structure’s chamber were quantified and presented in the form of a ratio relative to the incident wave height, respectively, which are then presented as a function of the relative immersion depth (D/d) and the relative structure width (B/Lp), where D = the depth of immersion, d = the water depth, B = the structure width and Lp = the wavelength corresponding to the peak wave period. The measured wave modification in front of the structure and in the breakwater’s chamber were quantified and presented in the form of a ratio relative to the incident wave height, respectively. It is found that the wave attenuation ability of the SCB model improves with the increase of D/d and B/Lp. The SCB performs better as an energy dissipater than as a wave reflector.

scholarly journals A Phenomenological Study of Lab-Scale Tidal Turbine Loading under Combined Irregular Wave and Shear Flow Conditions

2021 ◽  
Vol 9 (6) ◽  
pp. 593
Author(s):  
Matthew Allmark ◽  
Rodrigo Martinez ◽  
Stephanie Ordonez-Sanchez ◽  
Catherine Lloyd ◽  
Tim O’Doherty ◽  
...  
Keyword(s):  
Shear Flow ◽  
Phenomenological Study ◽  
Spectral Characteristics ◽  
Irregular Waves ◽  
Flow Structures ◽  
Wave Impact ◽  
Power Extraction ◽  
Irregular Wave ◽  
Cross Covariance ◽  
The Impact

Tidal devices are likely to faced with shear flows and subjected to various wave climates. The paper presents an experimental study of the combined impacts of shear profile and irregular waves on the loading of a 1/20th scale device operating at peak power extraction. The experiments presented were conducted at various depths to facilitate analysis of the effects of the shear flow and wave impact on the device at various positions in the water column. The fluid field was measured at three different upstream positions and at three depths (top, middle and bottom of the rotor) for each experiment; in doing so, data from the device were captured three times. The fluid measurements were of a high quality and were analysed to present the structure flow upstream of the device, which contained velocity and turbulence profiles. The upstream measurement was utilised to understand the development of flow structures in the approach to the device, and the impact of the flow structures measured was confirmed via cross-covariance calculations. The long datasets gathered were used to produce full rotational probability density functions for the blade-root-bending moments for three blades. The spectral characteristics were also considered, and showed that rotor loading quantities are less reactive to smaller scale flow structures.

scholarly journals A Calculation Method for the Sloshing Impact Pressure Imposed on the Roof of a Passive Water Storage Tank of AP1000

2016 ◽  
Vol 2016 ◽  
pp. 1-8 ◽  
Author(s):  
Daogang Lu ◽  
Xiaojia Zeng ◽  
Junjie Dang ◽  
Yu Liu
Keyword(s):  
Wave Height ◽  
Storage Tank ◽  
Water Storage ◽  
Impact Pressure ◽  
Experimental Result ◽  
Extreme Condition ◽  
Nonlinear Phenomenon ◽  
Maximum Wave Height ◽  
Water Storage Tank ◽  
The Impact

There is a large water storage tank installed at the top of containment of AP1000, which can supply the passive cooling. In the extreme condition, sloshing of the free surface in the tank may impact on the roof under long-period earthquake. For the safety assessment of structure, it is necessary to calculate the impact pressure caused by water sloshing. Since the behavior of sloshing impacted on the roof is involved into a strong nonlinear phenomenon, it is a little difficult to calculate such pressure by theoretical or numerical method currently. But it is applicable to calculate the height of sloshing in a tank without roof. In the present paper, a simplified method was proposed to calculate the impact pressure using the sloshing wave height, in which we first marked the position of the height of roof, then produced sloshing in the tank without roof and recorded the maximum wave height, and finally regarded approximately the difference between maximum wave height and roof height as the impact pressure head. We also designed an experiment to verify this method. The experimental result showed that this method overpredicted the impact pressure with a certain error of no more than 35%. By the experiment, we conclude that this method is conservative and applicable for the engineering design.

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