Analysis of the hydrodynamic performance of three- and four-fin surfboards using computational fluid dynamics

This study investigates the hydrodynamic performance of three- and four-fin surfboard configurations using the computational fluid dynamics (CFD)/CFX approach. CFD models of three- and four-fin configurations were setup inside a rectangular domain using CFX meshing. Comparisons of performance were evaluated by analysing both lift and drag coefficients for each fin system as a function of the angle of incidence at various speeds. The two-equation k-ॉ turbulence model was used as the base for simulations of flow velocities of 3, 5, 7 and 10 m/s. In addition the seven-equation Reynolds stress (RSM) turbulence model was also employed for flow velocities of 10 and 25 m/s in order to compare the predictions of the k-ॉ turbulence model. Results demonstrated that the maximum lift for the three-fin configuration occurred at a smaller angle of incidence than for the four-fin design. However, the magnitude of maximum lift was the same for both designs under the operating conditions considered in this study. These results imply that if a surfer desires a greater degree of manoeuvrability (ideal in regular surfing), then the three-fin configuration would be more appropriate in comparison to the four-fin configuration. This is because the three-fin design is more efficient at generating lift during smaller angles of attack compared to the four-fin design. However, if stability and speed in the surfboard is preferred (favourable in big wave surfing), then the four-fin configuration would be more suitable owing to less lift and drag at smaller incidence angles.