Marine renewable energy technologies, such as tidal stream turbines, have the potential to generate large amounts of electricity from ocean cycles. However, the blades of these turbines must stay submerged for long periods of time, leading to the buildup of organic material on their surfaces, otherwise known as biofouling. This buildup can reduce turbine efficiency and require frequent maintenance.

Peyvastehnejad et al. used computer modeling to examine the effect of employing a textured surface on biofouling in turbulent conditions. Their approach is inspired by marine animals, like the brill fish, that employ similar textures to keep their bodies clean.

Encouraged by the promising results for similar designs in static conditions, the researchers wanted to explore the performance in turbulent conditions.

The team simulated a surface featuring an array of rectangular prisms spaced at regular intervals, varying the texture spacing to find the optimal design. While small, closely packed textures can keep most organisms from attaching in the first place, they also create regions of low shear stress that cannot remove them once they anchor. Larger gaps create increased shear forces even in the lee of the textures.

“These results suggest that different surface modifications can be combined and exploited to combat biofouling that would remain effective for a range of flow conditions,” said author Amin Peyvastehnejad.

The team plans to follow up with field and laboratory tests to validate their simulations.

“We will rely on a purpose-built marine test platform that emulates conditions over a full-scale marine hydroturbine along with a newly built turbulent tunnel to study biofouling growth and detachment,” said author Yan Delauré.

Source: “On biomimetic surface texturing and its impact on turbulent flow and hydrodynamic forces acting on an early-stage bio-fouling organism,” by A. Peyvastehnejad, F. Regan, C. Richards, A. Delgado, P. Daly, J. Grande, and Y. M. C. Delaure, Physics of Fluids (2024). The article can be accessed at https://doi.org/10.1063/5.0184298.