The variations on the aerodynamics of a world-ranked wheelchair sprinter in the key-moments of the stroke cycle: A numerical simulation analysis

Abstract

Biomechanics plays an important role helping Paralympic sprinters to excel, having the aerodynamic drag a significant impact on the athlete's performance. The aim of this study was to assess the aerodynamics in different key-moments of the stroke cycle by Computational Fluid Dynamics. A world-ranked wheelchair sprinter was scanned on the racing wheelchair wearing his competition gear and helmet. The sprinter was scanned in three different positions: (i) catch (hands in the 12h position on the hand-rim); (ii) the release (hands in the 18h position on the hand-rim) and; (iii) recovery phase (hands do not touch the hand-rim and are hyperextended backwards). The simulations were performed at 2.0, 3.5, 5.0 and 6.5 m/s. The mean viscous and pressure drag components, total drag force and effective area were retrieved after running the numerical simulations. The viscous drag ranged from 3.35 N to 2.94 N, pressure drag from 0.38 N to 5.51 N, total drag force from 0.72 N to 8.45 N and effective area from 0.24 to 0.41 m2. The results pointed out that the sprinter was submitted to less drag in the recovery phase, and higher drag in the catch. These findings suggest the importance of keeping an adequate body alignment to avoid an increase in the drag force.

Fig 1

Three different scanned positions: (i) catch (i.e., the beginning of the propulsive phase, being the hands in the 12h position on the hand-rim); (ii) the release (i.e., hands in the 18h position on the hand-rim) and; (iii) recovery phase (i.e., hands do not touch the hand-rim and are hyperextended backwards) respectively.

Fig 2. Wheelchair-athlete system in the enclosure.

Fig 3. Viscous drag over the stroke cycle at 2.0 m/s (black column), 3.5m/s (dark grey column), 5.0 m/s (light grey column) and 6.5 m/s (white column).

Fig 4. Pressure drag force over the stroke cycle at 2.0 m/s (black column), 3.5m/s (dark grey column), 5.0 m/s (light grey column) and 6.5 m/s (white column).

Fig 5. Total drag force over the stroke cycle at 2.0 m/s (black column), 3.5m/s (dark grey column), 5.0 m/s (light grey column) and 6.5 m/s (white column).

Fig 6. Effective area over the stroke cycle at 2.0 m/s (black column), 3.5m/s (dark grey column), 5.0 m/s (light grey column) and 6.5 m/s (white column).