Hydrodynamic characteristics of a swimmer's hand

The main purpose of this study was to develop a model for calculating fords produced by a swimmer's hand, with the thumb adducted, accelerating in the direction of flow. The model included coefficients to account for the velo city and acceleration of the hand. These coefficients were designed to calc ulate forces in the direction opposite the motion (drag) and two components of lift orthogonal to the direction of motion. To determine the coefficien ts, three-dimensional forces acting on a resin cast of a swimmer's hand wer e recorded while accelerating the hand from rest to 0.45 m . s(-1) and 0.6 m . s(-1) in a towing tank. The hand orientation was varied throughout the entire range at 5 degrees increments. Three-dimensional surfaces describing the magnitude of the coefficients as functions of pitch and sweepback angl e were produced. It was found that acceleration coefficients as well as vel ocity coefficients are required for accurate modeling of the forces produce d by the hand in swimming. The forces generated by the hand are greatest wh en pitch angles approach 90 degrees due to the large contribution by the dr ag component. However, at pitch angles near 45 degrees and sweepback angles near 45 degrees and 135 degrees, lift forces contribute substantially.