Solitary wave dynamics and vortex fields near submerged slotted barriers
Year: 2024
Type: article
Abstract: Protecting coastal areas employing artificial structures is an important issue for the coastal engineering community. This study proposes a submerged, vertical, bottom-mounted screen with horizontal slots for reducing wave energy. When an incident wave encounters such an obstacle, it splits into transmitted and reflected waves. In addition, part of the wave energy is converted into kinetic energy of the vortex field due to flow separation from the structure walls. The study is focused on evaluating the hydraulic performance of this breakwater in terms of wave reflection and transmission coefficients. Circulation processes around the structure are also considered for deriving information about the directions and intensity of water exchange flows and bottom erosion. The problem is analyzed in the vertical plane, where the structure is considered a slotted barrier. It is assumed that the barrier comprises three impermeable elements and takes one of two possible configurations when its lower element either lies on the bottom or there is a gap between this element and the seabed. To identify the most suitable design, a numerical investigation of solitary wave interaction with slotted barriers of various shapes and porosity is carried out. The developed numerical procedure combines the boundary integral equation method used to determine free surface deformations and the hybrid vortex scheme for simulating the vortex field generated by the wave. The validity of the methodology is checked by the experimental research in the hydrodynamic tank of the Institute of Hydromechanics and by comparison with the data from other studies available in the literature. The solitary wave of non-dimensional amplitude A_i/h=0.2 is examined for the entire numerical experiment. Analysis of the free-surface evolution, as well as energy transmission and reflection coefficients, revealed that the protective properties of the structure deteriorate with increasing barrier porosity. In addition, permeability has a greater effect on high and narrow barriers than on lower and wider ones. Analysis of the vortex field created by the solitary wave around the slotted barrier revealed an intricate flow pattern on the leeward side. This pattern consists of two pairs of large-scale counter vortices, whose interaction forms downward and upward water flows along the structure. These vortices push the liquid through the gaps to the windward side, establishing reverse flows between the close zone and the open sea. This is a reason for the increase in water exchange intensity several times between different sides of the structure compared to an impermeable barrier. The data obtained infer that a slotted barrier of porosity 0.2-0.3 will be the most successful among structures of this type, both for shore protection and sustaining the health of the coastal ecology.
Source: Hydrodynamics and acoustics
Authors: I. M. Gorban, A. S. Korolova, V. A. Voskoboinick, V. M. Vovk
Language: English
Topic: Coastal and Marine Dynamics
Subfield: Earth-Surface Processes
Field: Earth and Planetary Sciences
Domain: Physical Sciences
Open Access status: hybrid
OpenAlex ID: W4411121512