Study of the Propulsive Potential of the Hand and Forearm in Swimming

Abstract

Computational Fluid Dynamics (CFD) has been used in biomechanics studies applied to medicine and sport. Concerning sports, the main results suggested that a three dimensional CFD analysis of a human form could provide useful information about swimming. PURPOSE: To analyze the propulsive force in a swimmer hand/forearm 3-D segment using CFD. METHODS: A 3-D domain was created to simulate the fluid flow around a model of a swimmer hand and forearm. Models were created by computerized tomography scans of a male swimmer. Steady-state computational fluid dynamics analyses were performed. Flow velocities were chosen to be within or near the range of typical hand velocities during the swimming underwater path: from 0.5 m/s to 4.0 m/s. Angles of attack of hand/forearm models of 0°, 45° and 90°, with sweepback angles of 0°, 90°, 180° and 270° were used for the calculations. The combined hand and forearm forces were decomposed into drag (CD) and lift (CL) coefficients. RESULTS: In table 1 the values of CD and CL obtained for the different angles of attack and sweepback angles are presented. Both CD and CL remained constant throughout the flow velocities tested.Table 1: CD and CL values for the different angles of attack and sweepback angles (V=2.0 m/s).CONCLUSIONS: The CD was the main responsible for the hand/forearm propulsion, with a maximum value at an angle of attack of 90°. The CL seems to play an important role at an angle of attack of 45°, especially when the little finger leads the motion (sweepback angle = 180°). These data confirm recent studies reporting supremacy of drag component and an important contribution of the lift force to the overall propulsive force generation by the hand/forearm in swimming phases, when the angle of attack nears 45°. Supported by FCT (SFRH/BD/25241/2005; POCTI/10/58872/2004).