Chen Zhifeng, Fang Haisheng
Zhejiang College of Construction, Hangzhou 311231, China.
J Biomech Eng. 2011 Sep;133(9):091001. doi: 10.1115/1.4004947.
Numerical simulation is conducted to evaluate the wind and posture effects on the aerodynamic performance of a skier during the flight stage. Both steady and unsteady models are applied on a 2D geometry. Using the Fluent code, the fundamental equations of fluid flow are solved simultaneously. In particular we focus on the influence of wind speed and direction on aerodynamic forces with several different postures of the skier in steady modeling. For a chosen case, the unsteady models are used to predict the transient characteristics of streamline distributions and aerodynamic forces. It is found that the skier's postures, wind speed, and direction play a significant role. The wind condition affects the pressure force (the form drag) on the skier and makes it a resistance or thrust regarding wind directions. The optimized posture with a minimization of resistance under a facing wind is determined as a moving-forward body of the skier. The unsteady modeling reveals that the wake around the skier and aerodynamic forces are strongly dependent on time. This initial study not only provides a qualitative and theoretical basis for the athletes to understand the effects of wind and postures, and then to optimize their postures according to the wind condition during the flight stage of skiing, but also builds the foundation for the systematic study of skiing process with more advanced CFD models in the future.
进行数值模拟以评估飞行阶段风及姿势对滑雪者空气动力学性能的影响。稳态模型和非稳态模型均应用于二维几何形状。使用Fluent软件求解流体流动的基本方程。在稳态建模中，我们特别关注风速和风向对处于几种不同姿势的滑雪者空气动力的影响。对于选定的案例，使用非稳态模型预测流线分布和空气动力的瞬态特性。结果发现，滑雪者的姿势、风速和风向起着重要作用。风况会影响作用在滑雪者身上的压力（形状阻力），并根据风向使其成为阻力或推力。在迎风情况下使阻力最小化的优化姿势被确定为滑雪者向前移动的身体姿态。非稳态建模表明，滑雪者周围的尾流和空气动力强烈依赖于时间。这项初步研究不仅为运动员理解风和姿势的影响，进而在滑雪飞行阶段根据风况优化姿势提供了定性和理论基础，也为未来使用更先进的计算流体动力学（CFD）模型对滑雪过程进行系统研究奠定了基础。
