scholarly journals Reduction of Wave Overtopping and Force Impact at Harbor Quays Due to Very Oblique Waves

2020 ◽  
Vol 8 (8) ◽  
pp. 598
Author(s):  
Sebastian Dan ◽  
Corrado Altomare ◽  
Tomohiro Suzuki ◽  
Tim Spiesschaert ◽  
Toon Verwaest
Keyword(s):  
Experimental Tests ◽  
Wave Impact ◽  
Wave Overtopping ◽  
Oblique Waves ◽  
Quay Wall ◽  
Force Impact ◽  
Force Reduction ◽  
Wave Induced ◽  
Best Fit ◽  
Sea Dike

Physical model experiments were conducted in a wave tank at Flanders Hydraulics Research, Antwerp, Belgium, to characterize the wave overtopping and impact force on vertical quay walls and sloping sea dike (1:2.5) under very oblique wave attack (angle between 45° and 80°). This study was triggered by the scarce scientific literature on the overtopping and force reduction due to very oblique waves since large reduction is expected for both when compared with the perpendicular wave attack. The study aimed to compare the results from the experimental tests with formulas derived from previous experiments and applicable to a Belgian harbor generic case. The influence of storm return walls and crest berm width on top of the dikes has been analyzed in combination with the wave obliqueness. The results indicate significant reduction of the overtopping due to very oblique waves and new reduction coefficients were proposed. When compared with formulas from previous studies the proposed coefficients indicate the best fit for the overtopping reduction. Position of the storm return wall respect to the quay edge rather than its height was found to be more important for preventing wave induced overtopping. The force reduction is up to approximately 50% for the oblique waves with respect to the perpendicular wave impact and reduction coefficients were proposed for two different configurations a sea dike and vertical quay wall, respectively.

A Theoretical Model for Ship–Wave Impact Generated Sea Spray

2020 ◽  
Vol 143 (4) ◽  
Author(s):  
Shafiul Mintu ◽  
David Molyneux ◽  
Bruce Colbourne
Keyword(s):  
Theoretical Model ◽  
Field Measurements ◽  
Operating Conditions ◽  
Ship Motions ◽  
Wave Impact ◽  
Fishing Vessels ◽  
Semi Empirical ◽  
Wave Induced ◽  
Analytical Expressions ◽  
Ship Speed

Abstract Spray generated by ships traveling in cold oceans often leads to topside icing, which can be dangerous to vessels. Estimation of the spray flux is a first step in predicting icing accumulation. The amount of spray water, the duration of exposure to the spray, and the frequency at which the spray is generated are all important parameters in estimating the spray flux. Most existing spray flux formulae are based on field observations from small fishing vessels. They consider meteorological and oceanographic parameters but neglect the vessel behavior. Ship heave and pitch motions, together with ship speed, determine the frequency of spray events. Thus, the existing formulae are not generally applicable to different sizes and types of vessels. This paper develops simple methods to quantify spray properties in terms that can be applied to vessels of any size or type. Formulae to estimate water content and spray duration are derived based on principles of energy conservation and dimensional analysis. To estimate spray frequency considering ship motions, a theoretical model is proposed. The model inputs are restricted to ship’s principal particulars, operating conditions, and environmental conditions. Wave-induced motions are estimated using semi-empirical analytical expressions. A novel spray threshold is developed to separate deck wetness frequency from spray frequency. Spray flux estimates are validated against full-scale field measurements available in the open literature with reasonable agreement.

Ship-Wave Impact Generated Sea Spray: Part 2 — Formulating Spray Frequency

2020 ◽  
Author(s):  
Shafiul A. Mintu ◽  
David Molyneux ◽  
Bruce Colbourne
Keyword(s):  
Field Measurements ◽  
Operating Conditions ◽  
Sea Spray ◽  
Ship Motions ◽  
Empirical Formulas ◽  
Wave Impact ◽  
Quick Estimate ◽  
Semi Empirical ◽  
Wave Induced ◽  
Analytical Expressions

Abstract In certain, but not all, circumstances a cloud of spray forms after a wave impacts a ship. The frequency of spray events affects the icing process. Previous spray frequency formulas are derived empirically from field observations considering only the ship’s forward speed and oceanographic conditions. The significance of various degrees of ship motions on the spray frequency is ignored. However in reality, the interrelationships of heave and pitch motions under wave actions together with surge motion determine the number of spray events that a ship may experience in a given period of time. This paper introduces a theoretical model for estimating the frequency of sea spray considering ship motions. Ship motions can be easily estimated by strip/panel methods. However, in this work, the aim was to develop a simple framework for a quick estimate of spray frequency. The model inputs are, therefore, restricted to ship’s principal particulars, its operating conditions, and the environmental conditions. The wave-induced motions are estimated by semi empirical analytical expressions. A novel spray threshold is developed to keep the deck wetness frequency separated from the spray frequency. The proposed spray frequency formula is validated against available full-scale field measurements from a Russian fishing vessel, MFV Narva, and reasonable agreement is found. Limitations of previous empirical formulas are also discussed.

Experimental Observations and Numerical Simulations of Wave Impact Forces on Recurved Parapets Mounted Above a Vertical Wall

2009 ◽  
Author(s):  
David Newborn ◽  
Nels Sultan ◽  
Pierre Beynet ◽  
Tim Maddux ◽  
Sungwon Shin ◽  
...  
Keyword(s):  
Numerical Model ◽  
Numerical Simulations ◽  
Shear Force ◽  
Experimental Testing ◽  
Vertical Wall ◽  
Experimental Tests ◽  
Vertical Force ◽  
Base Shear ◽  
Wave Impact ◽  
Overturning Moment

Large-scale hydraulic model tests and detail numerical model investigations were conducted on recurved wave deflecting structures to aid in the design of wave overtopping mitigation for vertical walls in shallow water. The incident wave and storm surge conditions were characteristic return period events for an offshore island on the North Slope of Alaska. During large storm events, despite depth-limited wave heights, a proposed vertical wall extension was susceptible to wave overtopping, which could potentially cause damage to equipment. Numeric calculations were conducted prior to the experimental tests and were used to establish the relative effectiveness of several recurved parapet concepts. The numerical simulations utilized the COrnell BReaking waves and Structures (COBRAS) fluid modeling program, which is a Volume-of-Fluid (VOF) model based on Reynolds Averaged Navier-Stokes equations [1] [2]. The experimental testing was conducted in the Large Wave Flume (LWF) at Oregon State University, O.H. Hinsdale Wave Research Laboratory. The experimental test directly measured the base shear force, vertical force, and overturning moment applied to the recurved parapets due to wave forcing. Wave impact pressure on the parapet and water particle velocities seaward of the wall were also measured. Results from the experimental testing include probability of exceedance curves for the base shear force, vertical force, and overturning moment for each storm condition. Qualitative comparisons between the experimental tests and the COBRAS simulations show that the numerical model provides realistic flow on and over the parapet.

scholarly journals Surface Wave Impact When Simulating Midlatitude Storm Development

2017 ◽  
Vol 34 (1) ◽  
pp. 233-248 ◽  
Author(s):  
Lichuan Wu ◽  
David Sproson ◽  
Erik Sahlée ◽  
Anna Rutgersson
Keyword(s):  
Time Resolution ◽  
Roughness Length ◽  
Coupled Model ◽  
Horizontal Resolution ◽  
Wave Impact ◽  
Storm Intensity ◽  
Dynamic Roughness ◽  
Induced Stress ◽  
Coupling Time ◽  
Wave Induced

AbstractSurface gravity waves, present at the air–sea interface, can affect the momentum flux and heat fluxes by modifying turbulence in the lower layers of the atmosphere. How to incorporate wave impacts into model parameterizations is still an open issue. In this study, the influence of a dynamic roughness length (considering instantaneous wave-induced stress), horizontal resolution, and the coupling time resolution between waves and the atmosphere on storm simulations are investigated using sensitivity experiments. Based on the simulations of six midlatitude storms using both an atmosphere–wave coupled model and an atmospheric stand-alone model, the impacts are investigated. Adding the wave-induced stress weakens the storm intensity. Applying a roughness length tuned to an average friction velocity is not enough to capture the simulation results from “true” wave-related roughness length. High-horizontal-resolution models intensify the simulation of storms, which is valid for both coupled and uncoupled models. Compared with the atmospheric stand-alone model, the coupled model (considering the influence of dynamic roughness length) is more sensitive to the model horizontal resolution. During reasonable ranges, the coupling time resolution does not have a significant impact on the storm intensity based on the limited experiments used in this study. It is concluded that the dynamic wave influence (instantaneous wave influence) and the model resolution should be taken into account during the development of forecast and climate models.

Numerical simulation of irregular wave overtopping against a smooth sea dike

2012 ◽  
Vol 26 (1) ◽  
pp. 153-166 ◽  
Author(s):  
Xiao-yu Guo ◽  
Ben-long Wang ◽  
Hua Liu
Keyword(s):  
Numerical Simulation ◽  
Wave Overtopping ◽  
Irregular Wave ◽  
Sea Dike

scholarly journals Regression Analysis of Bond Parameters between Corroded Rebar and Concrete Based on Reported Test Data

2018 ◽  
Vol 2018 ◽  
pp. 1-18 ◽  
Author(s):  
H. J. Zhou ◽  
Y. F. Zhou ◽  
Y. N. Xu ◽  
Z. Y. Lin ◽  
F. Xing ◽  
...  
Keyword(s):  
Regression Analysis ◽  
Bond Strength ◽  
Crack Width ◽  
Experimental Tests ◽  
Test Results ◽  
Bond Slip ◽  
Regression Effect ◽  
Pull Out ◽  
Maximum Crack ◽  
Best Fit

Reinforcement corrosion is a major cause of degradation in reinforced concrete structures. The fragile rust layer and cracking and spalling of the cover caused by splitting stress due to rust expansion can alter bond behaviors significantly. Despite extensive experimental tests, no stochastic model has yet incorporated randomness into the bond parameters model. This paper gathered published experimental data on the bond-slip parameters of pull-out specimens and beam-end specimens. Regression analysis was carried out to identify the best fit of bond strength and the corresponding slip value in the context of different corrosion levels from the recollected test results. An F-test confirmed the regression effect to be significant. Residual data were also analyzed and found to be well described by a normal distribution. Crack width data of the tested specimens were also collected. A regression analysis of the bond strength and maximum crack width was carried out given the comparative simplicity of measuring crack width versus rebar area loss. Results indicate that maximum crack width can also be used to predict bond strength degradation with similar variation magnitude.

scholarly journals Smoothed Particle Hydrodynamics Simulation of Wave Overtopping Characteristics for Different Coastal Structures

2012 ◽  
Vol 2012 ◽  
pp. 1-10 ◽  
Author(s):  
Jaan Hui Pu ◽  
Songdong Shao
Keyword(s):  
Porous Material ◽  
Smoothed Particle Hydrodynamics ◽  
Free Particle ◽  
Fluid Pressure ◽  
Wave Structure ◽  
Wave Impact ◽  
Wave Overtopping ◽  
Coastal Structure ◽  
Particle Hydrodynamics ◽  
Smoothed Particle

This research paper presents an incompressible smoothed particle hydrodynamics (ISPH) technique to investigate a regular wave overtopping on the coastal structure of different types. The SPH method is a mesh-free particle modeling approach that can efficiently treat the large deformation of free surface. The incompressible SPH approach employs a true hydrodynamic formulation to solve the fluid pressure that has less pressure fluctuations. The generation of flow turbulence during the wave breaking and overtopping is modeled by a subparticle scale (SPS) turbulence model. Here the ISPH model is used to investigate the wave overtopping over a coastal structure with and without the porous material. The computations disclosed the features of flow velocity, turbulence, and pressure distributions for different structure types and indicated that the existence of a layer of porous material can effectively reduce the wave impact pressure and overtopping rate. The proposed numerical model is expected to provide a promising practical tool to investigate the complicated wave-structure interactions.

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