Kudo Shigetada, Vennell Ross, Wilson Barry, Waddell Neil, Sato Yohei
School of Physical Education, University of Otago, Dunedin, New Zealand.
J Biomech. 2008 Dec 5;41(16):3502-5. doi: 10.1016/j.jbiomech.2008.09.022. Epub 2008 Nov 18.
The purpose of this study was to quantify the effect of wave drag due to surface penetration on drag and lift forces (C(d) and C(l)) acting on a hand model. The values of C(d) and C(l) had been acquired to gain the hydrodynamic characteristics of the swimmer's hand and predict force on the swimmer's hand. These values have also been used to benchmark computational fluid dynamics analysis. Because the previous studies used a hand/forearm model which penetrated the water's surface, the values of C(d) and C(l) include the effect of the surface wave on the model. Wave formation causes pressure differences between the frontal and rear sides of a surface-penetrating model as a result of depressions and elevations in the water's surface. This may be considered as wave drag due to surface penetration. Fluid forces due to wave drag on the forearm should not be included in the measured C(d) and C(l) of a swimmer's hand that does not sweep near the water's surface. Two hand/forearm models are compared, one with the hand rigidly connected to the forearm. The other model was constructed to isolate the fluid forces acting on the hand from the influence of wave drag on the forearm. The measurements showed that the effect of wave drag on the hand model caused large increases in the values of C(d), up to 46-98% with lesser increases in C(l) of 2-12% depending on the hand orientation. The present study provides an improved method to determine the values of C(d) and C(l) that eliminates the effect of wave drag on a hand/forearm model by isolating the measurement of fluid forces on the forearm of the hand/forearm model in order to separately acquire the forces on the hand.
本研究的目的是量化由于表面穿透引起的波阻对手模型上的阻力和升力（C(d) 和 C(l)）的影响。获取 C(d) 和 C(l) 的值是为了获得游泳者手部的水动力特性，并预测作用在游泳者手上的力。这些值也被用于基准计算流体动力学分析。由于先前的研究使用了穿透水面的手/前臂模型，C(d) 和 C(l) 的值包括了表面波对模型的影响。表面波的形成会导致水面出现凹陷和隆起，从而在穿透水面的模型的前后侧之间产生压力差。这可被视为由于表面穿透引起的波阻。对于不靠近水面划动的游泳者手部，前臂上由于波阻产生的流体力不应包含在测量的 C(d) 和 C(l) 中。比较了两种手/前臂模型，一种是手与前臂刚性连接。另一种模型的构建是为了将作用在手上的流体力与前臂上的波阻影响隔离开来。测量结果表明，波阻对手模型的影响导致 C(d) 值大幅增加，高达 46 - 98%，而 C(l) 的增加幅度较小，为 2 - 12%，这取决于手的方向。本研究提供了一种改进方法来确定 C(d) 和 C(l) 的值，通过隔离手/前臂模型前臂上的流体力测量，消除波阻对手/前臂模型的影响，以便分别获取作用在手上的力。
