A model for the scattering of long waves by slotted breakwaters in the presence of currents

Slotted breakwaters have been used to provide economical protection from waves in harbors where surface waves and currents may co-exist. In this paper, the effects of currents on the wave scattering by slotted breakwaters are investigated by using a simple model. The model is based on a long wave approximation. The effects of wave height, barrier geometry and current strength on the reflection and transmission coefficients are examined by the model. The model results are compared with recent experimental data. It is found that both the wave-following and wave-opposing currents can increase the reflection coefficient and reduce the transmission coefficient. The model can be used to study the interaction between long waves and slotted breakwaters in coastal waters.

Wave Scattering by Double Slotted Barriers in A Steady Current:Experiments

The adoption of slotted breakwaters can be an ideal option in the protection of very large near-shore floating struc-trees that may extend offshore to a considerable water depth. In this paper, we experimently investigated the behaviour of wave transmission and reflection coefficients of double slotted barriers in the presence of a steady opposing current. The experimental results show that opposing currents have only minor effects on wave reflection, but can significantly reduce the wave transmission through double slotted barriers. The experimental results suggest that coastal currents should be taken into consideration for an economical design of slotted breakwaters.

A Linear Theory for Wave Scattering by Double Slotted Barriers in Weak Steady Currents

Recent experimental results have shown that the presence of a steady current can significantly reduce the energy of transmitted waves. In this paper, a theory is developed to study the wave scattering by single or double vertical slotted barriers in the presence of a weak uniform current. The quasi-linear theory is based on an eigenfunction expansion method. Comparisons between theory and existing experimental results for both single slotted barrier and double slotted barriers show satisfactory agreements. In consideration of wave propagation in a weak current it is found that the friction factor used to characterize the head loss at the slotted barrier depends on both the geometry of the slotted barrier and the strength of the steady current.

Numerical Simulation of the Hydrodynamic Characteristics of the Porous I-type Composite Breakwater

Based on the three-dimensional Reynolds-averaged Navier-Stokes equation with the closure of renormalization group k-εturbulence model and volume of fluid method,a wave-breakwater interaction numerical flume was developed to examine the wave-structure interaction of the porous I-type composite(PITC)breakwater.The transmission and reflection coefficients of the breakwater at different wave steepness H/L are quantitatively analyzed,and the wave-dissipating performance of the breakwater is compared.By changing the submerged depth of the breakwater,the velocity field,and vorticity field in the wave propagation process are analyzed,and the optimal working water depth of the new breakwater is explored.The results show that the vertical wave force on the PITC breakwater is greater than the horizontal wave force.In addition,during the wave dissipation process,the transverse baffle provided by the new breakwater destroys the trajectory of the water particle.In the interior of the wave-breaking chamber,the water that enters from the gap of the permeable plate mixes with the water entering through the bottom hole.The turbulence created by this process further dissipates the wave energy.The relative submergence depth of h/d has a great influence on the hydrodynamic characteristics.When the relative depth is large,most of the wave energy enters the breakwater,the wave energy dissipation of the breakwater is large,and the wave-absorbing effect is good.These research results provide important referential data for the study of permeable plate breakwaters.