Optimizing arc-shaped breakwaters to protect coastal areas

Breakwaters are structures installed along coastlines to protect against the dangers of the seas. Storm surges can damage shorelines and inland buildings, and long waves, like tsunamis, are becoming more common due to climate change.

However, traditional, straight breakwaters are not perfect, so Shaik Firoj and Mohammad Saud Afzal investigated the hydrodynamic performance of convex arc-shaped breakwaters (ASBWs).

“Compared to straight breakwaters, [ASBWs] generate lower wave reflection and higher controlled flow patterns, and their geometry can be tuned to suit local wave conditions for optimal performance,” said Afzal.

Using a non-hydrostatic shallow water model called REEF3D::SFLOW, which incorporates the post-wave vortex formation at the edges of the ASBW, the researchers investigated the energy dissipation of waves and the vortices left in their wake after hitting the breakwater. They found that ASBWs with wider arcs spread the energy of an incoming wave more effectively, lowering the wave height after passing the ASBW.

However, the incidence angle of the wave also had an important effect on the flow behavior and vortex dynamics behind the breakwater. Even a moderate oblique angle shift reduced the sheltered zone, regardless of the ASBW’s arc shape.

In the future, the researchers want to use their methods to study concave ASBWs, V-shaped breakwaters, and straight breakwaters.

“I hope our findings help engineers design breakwaters that are both efficient and site-specific,” said Afzal. “By showing how arc geometry and wave incidence influence energy distribution, vortex formation, and sheltered zones, designers can optimize opening angles and orientation to maximize protection while controlling flow patterns.”

Source: “Hydrodynamic performance of arc-shaped breakwater: Role of geometry and obliquity,” by Shaik Firoj and Mohammad Saud Afzal, Physics of Fluids (2025). The article can be accessed at https://doi.org/10.1063/5.0282777 .