Hydraulic performance and wave loadings of perforated/slotted coastal structures: A review

Flow speed estimated by inverse modeling of sandy tsunami deposits: results from the 11 March 2011 tsunami on the coastal plain near the Sendai Airport, Honshu, Japan

This study develops a full solution for water wave reflection by a partially perforated caisson breakwater with a rubble mound foundation using multi-domain BEM (boundary element method). Regular and irregular waves are both considered. A quadratic pressure drop condition on caisson perforated wall is adopted, and direct iterative calculations are performed. Due to the use of quadratic pressure drop condition, the effect of wave height on the energy dissipation by the perforated wall is well considered. This study also develops an iterative analytical solution for wave reflection by a partially perforated caisson breakwater on flat bottom using matched eigenfunction expansion method. The reflection coefficients calculated by the multi-domain BEM solution and the analytical solution are in excellent agreement. The present calculated results also agree reasonably well with experimental data from different literatures. Suitable values of discharge coefficient and blockage coefficient in the quadratic pressure drop condition are recommended for perforated caissons. The effects of the wave steepness, the blockage coefficient of perforated wall and the relative wave chamber width on the reflection coefficient are clarified. The present BEM solution is simple and reliable. It may be used for predicting the reflection coefficients of perforated caisson breakwaters in preliminary engineering design.

Iterative multi-domain BEM solution for water wave reflection by perforated caisson breakwaters

Oblique wave interaction with rectangular porous structures of various configurations in two-layer fluid are analyzed in finite water depth. Wave characteristics within the porous structure are analyzed based on plane wave approximation. Oblique wave scattering by a porous structure of finite width and wave trapping by a porous structure near a wall are studied under small amplitude wave theory. The effectiveness of three types of porous structures—a semi-infinite porous structure, a finite porous structure backed by a rigid wall, and a porous structure with perforated front and rigid back walls—in reflecting and dissipating wave energy are analyzed. The reflection and transmission coefficients for waves in surface and internal modes and the hydrodynamic forces on porous structures of the aforementioned configurations are computed for various physical parameters in two-layer fluid. The eigenfunction expansion method is used to deal with waves past the porous structure in two-layer fluid assuming the associated eigenvalues are distinct. An alternate procedure based on the Green’s function technique is highlighted to deal with cases where the roots of the dispersion relation in the porous medium coalesce. Long wave equations are derived and the dispersion relation is compared with that derived based on small amplitude wave theory. The present study will be of significant importance in the design of various types of coastal structures used in the marine environment for the reflection and dissipation of wave energy.

Gravity wave interaction with porous structures in two-layer fluid

Comparison of analytical and numerical solutions for wave interaction with a vertical porous barrier

Closed-form solutions for wave reflection and transmission by vertical slotted barrier

An empirical formula for friction coefficient of a perforated wall with vertical slits

https://s-space.snu.ac.kr/bitstream/10371/67632/3/Revised.pdf

Wave interactions with multiple-row curtainwall-pile breakwaters

The friction coefficient in the permeability parameter of a perforated wall has been estimated on the basis of a best fit between measured and predicted values of such hydrodynamic coefficients as reflection and transmission coefficients. In the present study, an empirical formula for the friction coefficient is proposed in terms of known variables, i.e., the porosity and thickness of the perforated wall and the water depth. This enables direct estimation of the friction coefficient without invoking a best fit procedure. To validate the proposed formula, the reflection and transmission coefficients calculated by using the formula are compared with the experimental data for various types of structures including a perforated wall. It is also shown that the proposed formula can be used for irregular waves as well.

/pdf/calculation-of-permeability-parameter-of-perforated-wall-2gkel9n5zu.pdf

Calculation of permeability parameter of perforated wall

The matching condition at a perforated wall with vertical slits involves the permeability parameter, which can be calculated by two different methods. One is advantageous because all the related variables are known, but it gives wrong result in the limit of long waves. The other gives a correct result from short to long waves, but it requires the permeability parameter to be calibrated by comparing the mathematical and experimental results. In this paper, the permeability parameter for the latter method is given as a function of known variables without comparing the mathematical and experimental results.

Chang-Hwan Ji

Papers

Closed-form solutions for wave reflection and transmission by vertical slotted barrier

An empirical formula for friction coefficient of a perforated wall with vertical slits

Wave interactions with multiple-row curtainwall-pile breakwaters

Calculation of permeability parameter of perforated wall

Permeability Parameter of Perforated Wall With Vertical Slits