Computational fluid dynamics performance evaluation of grooved fins for surfboards

Abstract

In this paper, we used computational fluid dynamics simulation (ANSYS CFX) to compare the performance of surfboard fins with grooves (and a bumpy-leading edge) to conventional surfboard fins. The simulations predicted the performance of each type of fins in terms of hydrodynamic forces and their behavior for angles of attack up to 45 degrees. Our results indicated that the pressure contours around fins with grooves (and bumpy-leading edge) were lower compared to pressure contours around conventional fins. The grooved fins exhibited a 13 ± 1% reduction in drag (coupled with a much smaller reduction in lift) at the stall angle, contributing to an overall 11 ± 1% improvement in the lift-to-drag ratio compared to conventional fins. Graphical abstract

Understanding the relationship between surfing performance and fin design

“…By using surfboard fins that had been designed to include grooved surface features—in this case, a grooved outer surface (G1) or grooved outer and inner surface (G2)—we were able to evaluate whether an optimized design would contribute to improvements in surfing performance. As previously reported, including a grooved surface on the side fins resulted in an 11% improvement in the lift-to-drag ratio, calculated through computational fluid dynamics (CFD) 2 . This computational process treats fins (and surfboards) as rigid, with a seamless connection between fin and surfboards.…”

“…This process leads to fins and surfboard dissipating energy through mechanical flex (and vibrations), leading to increased drag and reduced speed. Therefore, the CFD estimations 2 should be treated as a best-case scenario or the maximum possible improvement in surfing performance.…”

“…The fins of a surfboard interact with the water flow around it to give the surfer control and maneuverability 2 . Previous research has shown that the design of a fin (construction, shape, surface features) 2 – 4 and the arrangement or number of fins 5 – 7 can influence the flow of water around the fin.…”

“…The fins of a surfboard interact with the water flow around it to give the surfer control and maneuverability 2 . Previous research has shown that the design of a fin (construction, shape, surface features) 2 – 4 and the arrangement or number of fins 5 – 7 can influence the flow of water around the fin. Based on fluid dynamics, changes to water flowing around a fin will change the lift and drag forces acting on the fin and, in turn, how the surfboard performs.…”

“…As the mechanical properties of sporting equipment can influence performance, it is imperative that athletes can identify equipment that is likely to enhance their functional performance. In surfing, we recently reported that the lift-to-drag ratio of surfing fins can be improved by 11% by adding a grooved outer edge to a commercial fin template 2 . However, this improvement was based on theoretical modelling using computational fluid dynamics rather than quantifying changes in the performance of surfers riding waves.…”