Water “diode” blocks waves but not boats

Waves can affect the speed and stability of boats in harbors, which can slow the vessels down and reduce port efficiency. But the physical barriers of traditional wave-blocking methods, such as breakwaters, salt marshes, and coastal vegetation, also block boats.

Han et al. designed and experimentally demonstrated a water wave-blocking device inspired by electrical diodes. The device blocks waves from one direction while allowing waves from the other direction to pass. It achieves this “water wave diode” effect through methods used to manipulate electromagnetic waves.

The refractive index of a medium describes how much it bends waves. The device created by the researchers integrates a refractive gradient index into the bottom of a waveguide structure made of metamaterials. As the structure of the waveguide varies in one direction, the refractive gradient index gradually increases, which allows water waves to propagate through the device. In the opposite direction, the refractive index gradually decreases, which reflects the waves.

The central channel of the device is hollow for boats to pass through in either direction, making it suitable for use in harbors and ocean freight transport.

“The reverse isolation capability of the water wave diode offers a novel approach for wave suppression,” said author Huanyang Chen. “The device is highly promising for enhancing the stability and navigational efficiency of maritime ports and holds significant potential for wave isolation applications in port engineering.”

The water wave diode in this study was 28 centimeters long and 1.54 centimeters wide. Next, the authors will experimentally test the wave suppression performance of a larger scale version of this device.

Source: “Water wave diodes,” by Linkang Han, Zixun Ge, Junke Liao, and Huanyang Chen, Physics of Fluids (2025). The article can be accessed at https://doi.org/10.1063/5.0247624 .

This paper is part of the Fluid-Structure Interaction Collection, learn more here .