Numerical Investigation of the Hydrodynamics of Changing Fin Positions within a 4-Fin Surfboard Configuration

Abstract

Most sports like surfing are highly developed. It is necessary to tease the last percentages out of the competitors and equipment—in the case of surfing the surfboard-fin-system—to win competitions or championships. In this computational investigation, a parameter study of the positioning of the two rear fins within a 4-fin configuration with fixed front fins on a surfboard is executed to find appropriate fin positions for specific surf situations. Four different inflow velocities are investigated. The RANS and URANS models combined with the SST k − ω turbulence model, which is available within the computational fluid dynamics (CFD) package STAR-CCM+, are used to simulate the flow field around the fins for angles of attack (AoA) between 0° and 45°. The simulation results show that shifting the rear fins toward the longitudinal axis of the surfboard lowers the maximum lift. Surfboards with 4-fin configurations are slower in nearly the whole range of AoA due to a higher drag force but produce a higher lift force compared to the 3-fin configuration. The lift and drag forces increase significantly with increasing inflow velocity. This study shows a significant influence of the rear fin positioning and the inflow velocity on lift and drag performance characteristics.

Expanded (Black) Cork for the Development of an Eco-Friendly Surfboard: Environmental Impact and Mechanical Properties

“…Finite Element Analysis (FEA) was employed to develop the surfboard's numerical model, to assess if the chosen design and materials could withstand all the loads and stress that originated during surf practice. Most of the studies with an engineering approach to surfboards focus on the fins [26][27][28][29] and make use of numerical simulation of the hydrodynamics-through computational fluid dynamics (CFD) software-to assess how their design, quantities and position affect the board's overall performance. To the best of the author's knowledge, no studies use FEA to simulate stresses and deformations on the surfboard's structure as a whole, only targeting the fins [30].…”

Understanding the relationship between surfing performance and fin design

“…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.…”

Numerical Investigation of the Hydrodynamic Characteristics of 3-Fin Surfboard Configurations

“…The simulation uses the k-ω shear-stress transport (SST) turbulence model to solve a flow of 5 m/s across the fins at 0 to 45 • . A similar study from Falk et al investigated the fin positioning of a four-fin configuration using a similar k-ω SST turbulence model [4]. Both these studies investigated not only steady-state flow but also presented transient flow field data, identifying vortex shedding phenomena at high angles and the wake interaction between fins.…”

“…Due to the variety of fin profiles used in the literature, the results from studies often have different coefficient magnitudes but similar trends. Many of the recent numerical studies have used a combination of these experimental results and other numerical studies to validate their results by recognising the similarities in lift and drag trends across multiple AOAs [2][3][4].…”