• Title/Summary/Keyword: impact breaking wave pressure

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Numerical investigation of solitary wave interaction with a row of vertical slotted piles on a sloping beach

  • Jiang, Changbo;Liu, Xiaojian;Yao, Yu;Deng, Bin
    • International Journal of Naval Architecture and Ocean Engineering
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    • v.11 no.1
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    • pp.530-541
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    • 2019
  • To improve our current understanding of tsunami-like solitary waves interacting with a row of vertical slotted piles on a sloping beach, a 3D numerical wave tank based on the CFD tool $OpenFOAM^{(R)}$ was developed in this study. The Navier-Stokes equations were employed to solve the two-phase incompressible flow, combining with an improved VOF method to track the free surface and a LES model to resolve the turbulence. The numerical model was firstly validated by our laboratory measurements of wave, flow and dynamic pressure around both a row of piles and a single pile on a slope subjected to solitary waves. Subsequently, a series of numerical experiments were conducted to analyze the breaking wave force in view of varying incident wave heights, offshore water depths, spaces between adjacent piles and beach slopes. Finally, a slamming coefficient was discussed to account for the breaking wave force impacting on the piles.

Prediction of Bow Flare Impact Pressure and Its Application to Ship Structure Design - Container Ship and PCC - (선수 플레어 충격압력 추정과 구조설계에의 응용 - 콘테이너선과 자동차 운반선 -)

  • 김용직;신기석;신찬호;강점문;김만수;김성찬;오수관;임채환;김대헌
    • Journal of the Society of Naval Architects of Korea
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    • v.40 no.3
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    • pp.29-36
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    • 2003
  • In rough seas, bow-flare regions of the fine ships (container ship and PCC) are subject to high impact pressures due to the bow-flare slamming. And many ships suffer structural damages in that region, even though they were built under the bow structure strengthening rules of the ship classes. So, a new design method for bow-flare structure is highly required. In this paper, a new prediction method of the bow-flare impact pressure (in terms of equivalent static pressure) acting on the fine ships' bow is presented. This method is based on the 11 fine ships' damage analysis and the mechanisms of water entry impact and breaking wave impact. Calculation results of the bow-flare impact pressure and the shell plate thickness are shown and discussed. Through the example calculations, it was found that the present method is useful for the structure design of the fine ships' bow.

Experimental Study for Downfall Pressure on the Floor behind Rubble-Mound Structure by Wave Overtopping: Non-Breaking Condition (월파에 의한 경사식구조물 배후면에 작용하는 낙하파압에 대한 실험적 연구: 비쇄파조건)

  • Lee, Jong-In;Moon, Gang Il;Kim, Young Il
    • Journal of Korean Society of Coastal and Ocean Engineers
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    • v.34 no.2
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    • pp.27-36
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    • 2022
  • The large uprush could be occurred when the waves hit the coastal structure and this uprush by wave could make the overtopping. The downfall of the wave overtopping water over the structure brought about the vertical impact loads. The vertical impact loads should be evaluated in order to design the pavement behind the crown wall however these loads were still unclear. In this study, the hydraulic model tests for the downfall impact loads by wave overtopping were performed and the various conditions were applied to the tests. The effect of the incident wave condition, the freeboard, the armour crest height and the height of the parapet were investigated. The test results showed that the parapet on the crown wall could reduce the wave overtopping however the inclusion of parapet could lead to the increased downfall wave pressures behind the crown wall. The empirical formulae were proposed for evaluating the maximum downfall pressures behind the crown wall of rubble mound structure.

CFD simulation of compressible two-phase sloshing flow in a LNG tank

  • Chen, Hamn-Ching
    • Ocean Systems Engineering
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    • v.1 no.1
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    • pp.31-57
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    • 2011
  • Impact pressure due to sloshing is of great concern for the ship owners, designers and builders of the LNG carriers regarding the safety of LNG containment system and hull structure. Sloshing of LNG in partially filled tank has been an active area of research with numerous experimental and numerical investigations over the past decade. In order to accurately predict the sloshing impact load, a new numerical method was developed for accurate resolution of violent sloshing flow inside a three-dimensional LNG tank including wave breaking, jet formation, gas entrapping and liquid-gas interaction. The sloshing flow inside a membrane-type LNG tank is simulated numerically using the Finite-Analytic Navier-Stokes (FANS) method. The governing equations for two-phase air and water flows are formulated in curvilinear coordinate system and discretized using the finite-analytic method on a non-staggered grid. Simulations were performed for LNG tank in transverse and longitudinal motions including horizontal, vertical, and rotational motions. The predicted impact pressures were compared with the corresponding experimental data. The validation results clearly illustrate the capability of the present two-phase FANS method for accurate prediction of impact pressure in sloshing LNG tank including violent free surface motion, three-dimensional instability and air trapping effects.

A Study on the Numerical Simulation Method of Two-dimensional Incompressible Fluid Flows using ISPH Method (ISPH법을 이용한 2차원 비압축성 유체 유동의 수치시뮬레이션 기법 연구)

  • Kim, Cheol-Ho;Lee, Young-Gill;Jeong, Kwang-Leol
    • Journal of the Society of Naval Architects of Korea
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    • v.48 no.6
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    • pp.560-568
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    • 2011
  • In SPH(Smoothed Particle Hydrodynamics) method, the fluid has been assumed that it is weakly compressible to solve the basic equations composed of Navier-Stokes equations and continuity equation. That leads to some drawbacks such as non-physical pressure fluctuations and a restriction as like small time steps in computation. In this study, to improve these problems we assume that the fluid is incompressible and the velocity-pressure coupling problem is solved by a projection method(that is, by ISPH method). The two-dimensional computation results of dam breaking and gravitational wave generation are respectively compared with the results of finite volume method and analytical method to confirm the accuracy of the present numerical computation technique. And, the agreements are comparatively acceptable. Subsequently, the green water simulations of a two-dimensional fixed barge are carried out to inspect the possibility of practical application to ship hydrodynamics, those correspond to one of the violent free surface motions with impact loads. The agreement between the experimental data and the present computational results is also comparatively good.

Structural Analysis of a Breakwater in Wave and Seismic Loads (파랑하중과 지진하중하의 방파제 구조해석)

  • Cho, Kyu-Nam
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.22 no.1
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    • pp.45-52
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    • 2009
  • In this paper, a guideline for designing breakwater in wave loads and in seismic loads is proposed. A simple model structure in breaking wave zone is examined using Morison equation in consideration with the effect of an impact load, for evaluation of the wave loads. As the impact load effect is not significant, pressure distributions according to Goda are applied for evaluation of wave loads on breakwater. Structural behavior of breakwater in wave loads can be obtained using the Goda method, as well. For seismic analysis, Ofunato and Hachinohe models, as well as an artificial seismic acceleration loads model, are adopted. Soil-structure interaction analysis is carried out to find the seismic load effect. It is found that, in certain cases, structural deformation in wave loads is in the same level as deformation that in seismic loads. Thus, it is our recommendation that these two loads are considered at the same level in breakwater design.