• Journal of Korean Society of Coastal and Ocean Engineers
• /
• v.24 no.3
• /
• pp.228-234
• /
• 2012

Two-dimensional hydraulic experiments for wave overtopping under non-breaking wave condition are conducted. The wave overtopping formula for vertical structure is suggested and the results are compared with EurOtop (2007). The relative water depth coefficient (${\gamma}_{kh}$) shows that almost the same coefficient is obtained for certain range (kh > 1.55) regardless of relative water depth, that is, although the relative water depth becomes larger, the relative water depth coefficient is almost same. When the wave steepness becomes larger the wave steepness coefficient decreases. The overtopping formula are expressed by relative freeboard(R) and non-dimensional wave overtopping rate(Q) and this formula has the form of exponential function. In this formula, the effects of wave period on wave overtopping are quantitatively investigated and suggested through the relative water depth coefficient(${\gamma}_{kh}$) and wave steepness coefficient(${\gamma}_s$).

• Journal of Korean Society of Coastal and Ocean Engineers
• /
• v.22 no.3
• /
• pp.149-155
• /
• 2010

The existing formula for estimating the wave overtopping are mainly about the perpendicularly incident wave to the structure and wave overtopping formula for the obliquely incident wave are rare. Moreover, these formula present only the overtopping reduction factor(${\gamma}_{\beta}$) with respect to the incident wave angle rather than the spatial distribution of overtopping along the structures because the length of model is relatively too short for the wave to propagate along the structure. In this study, the wave overtopping reduction factor considering the spatial variation of wave overtopping along the vertical wall is investigated using the hydraulic model tests and the results are compared with the those of EurOtop(2007). The wave overtopping reduction factor is modified for ${\beta}$ > $45^{\circ}$ condition.

• Journal of Korean Society of Coastal and Ocean Engineers
• /
• v.27 no.3
• /
• pp.175-181
• /
• 2015

In this study, two dimensional wave overtopping tests for vertical wall were performed and overtopping formulas were suggested for impulsive and non-impulsive wave conditions. The test results from this study were compared with those from EurOtop(2007). The wave overtopping formulas were derived and suggested considering the recent research trends, while the existing method used the diagram. The wave overtopping formulas have the form of exponential and power functions using non-dimensional variables for wave overtopping and freeboard heights for non-impulsive and impulsive condition, respectively. The wave overtopping formula and effective parameters for inclined superstructure were also suggested. It is analyzed that the locations of inclined superstructure do not have the significant effects on wave overtopping, that is, the wave overtopping rate were almost same for each locations.

• Journal of Korean Society of Coastal and Ocean Engineers
• /
• v.28 no.1
• /
• pp.1-6
• /
• 2016

The effect of reducing wave overtopping by use of the wave return wall was quantitatively analyzed based on physical experiments. The overtopping discharge for the arc seawall and the inclined seawall was measured and compared with the predictive formula that estimates reduction of overtopping by the wave return wall. When the overtopping discharge was relatively large ($q/{\sqrt{gH^3_s}}>10^{-3}$), the agreement in terms of overtopping reduction rate was fairly good between the prediction and the measurement. For the condition of smaller overtopping than the above criterion, however, the discrepancy was large between the predicted and measured result. In this context, it is required to develop a better formula for estimating reduction of wave overtopping by the wave return wall.

• 한국방재학회:학술대회논문집
• /
• 2008.02a
• /
• pp.443-445
• /
• 2008

Determination of allowable overtopping rate for coastal structure is a key point to determine the application of background of coastal structure while considering safety and economic efficiency. Thus, the accurate estimation of overtopping rate against coastal structure is essential. In general, estimation of overtopping against the coastal structure is based on an empirical formula or hydraulic experiment. In this study, we investigate the behavior of overtopping for rubble mound coastal structure with rubble armor stone and wave dissipating block using hydraulics experiment, and domestic or foreign design standard.

• Journal of Korean Society of Coastal and Ocean Engineers
• /
• v.35 no.3
• /
• pp.49-56
• /
• 2023

The allowable mean overtopping discharge is used as a design parameter for coastal structures. The crest elevation of coastal structures should ensure the wave overtopping discharge within acceptable limits for structural safety and the safety of pedestrians, vehicles, operations, and so on. In this study, two-dimensional physical model tests on typical rubble-mound structure geometries were performed and the the mean wave overtopping discharges under various water depth and wave conditions were measrued. The various test conditions were applied to the tests with the change of the wave steepness, relative freeboard and relative wave height. An empirical formula from the experimental data was proposed to predict the mean wave overtopping volumes.

• Journal of Korean Society of Coastal and Ocean Engineers
• /
• v.19 no.6
• /
• pp.606-613
• /
• 2007

This study investigates the behavior of a plunging wave and its associated runup and overtopping through velocity measurements and suggests an empirical formula for overtopping velocities on a structure. The plunging wave breaking in front of the structure generates very bubbly flow fields. For measurements of the two phase flow field of the breaking wave, particle image velocimetry and a modified optical method were employed. The obtained velocity fields were discussed in respect of the process of wave impinging, runup and overtopping. The overtopping velocity distribution is found to have a nonlinear profile showing a maximum magnitude at its front part. The relationship of self-similarity among dimensionless parameters is observed and used to obtain the regression formula to depict the overtopping velocity.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.41 no.6
• /
• pp.663-673
• /
• 2021

Normally, allowable mean overtopping discharge is used as a design parameter for coastal structures. The crest elevation of a structure must ensure wave overtopping discharge within acceptable limits for structural safety and the safety of pedestrians, vehicles, operations, and so on. Some researchers have alternatively proposed using the maximum individual wave overtopping volumes as design criteria during a design storm, since these can provide a better design measure than the mean overtopping rate. This study contributes to the knowledge on maximum individual overtopping volumes in Rayleigh-distributed wave conditions. Two-dimensional physical model tests on typical rubble mound structure geometries were performed, and the new measurement method for individual overtopping was adopted. An empirical formula was proposed to predict the maximum individual overtopping volumes based on the mean overtopping rate, and the reduction effects by the armor crest width on the mean wave overtopping discharge were assessed.

• Journal of Korean Society of Coastal and Ocean Engineers
• /
• v.18 no.4
• /
• pp.372-382
• /
• 2006

Most of the conventional breakwaters impermeable breakwaters which block seawater exchange between the outside and inside of the harbors. The blocking of seawater exchange may cause pollution of water in harbors. To solve the water pollution problem, various kinds of seawater exchange breakwaters have been proposed. Their types can be classified into the current type which uses tidal current, and the overtopping type which uses the wave energy. The overtopping type breakwaters require a discharge coefficient to calculate the rate of overtopping into the harbor. The present study is to compute the rate of overtopping with introduction of a correct discharge coefficient and to evaluate the effect of the overtopping type breakwater on the water qualify inside a harbor. The rate of overtopping was computed by using Forchheimer formula with time dependent mild-slope equation for various wave conditions. The formula has been generally used to calculate the overflow discharge in steady state river flows. The discharge coefficient, which is the key parameter of the calculation, was determined by a series of hydraulic model tests. The present scheme was applied to the seawater exchange section of the western breakwater of Jeju New Harbor's and the efficiency of that section was examined. The calculated results showed that the rate of overtopping into the harbor reached about $27.5m^3/s$ in the wave condition (wave height 3.7 m, wave period 8.5s, and wave direction NNW).

• Journal of Korean Society of Coastal and Ocean Engineers
• /
• v.36 no.1
• /
• pp.11-19
• /
• 2024

In this study, the program was modified by adding the empirical formula of EurOtop (2018) to enable calculation of wave overtopping on armoured slope structures in the FUNWAVE-TVD model using the fully nonlinear Boussinesq equation. The validity of the modified numerical model was verified by comparing it with CLASH data and experiment data for the rubble mound structure. This model accurately reproduced the change in wave overtopping rate according to the difference in the roughness factor of the armoured block, and well reproduced the rate of decrease in wave overtopping rate due to the increase in relative freeboard. The overtopping rate of the armoured slope structures showed significant differences depending on the positioning condition of the armoured blocks. When Tetrapods were placed with regular positioning, the overtopping rate increased significantly compared to when they were placed with random positioning, and it was consistent with when they were placed with Rocks. Meanwhile, when rocks were placed in one row, the wave overtopping rate was greater than when rocks were placed in two rows, which is believed to be due to the influence of the roughness and permeability of the structure's surface.