Unsteady aerodynamics simulation of ski jumping from takeoff to landing motion#
Makoto Tsubokura (Kobe Univ./Riken)
Abstract#
This study was designed to develop a computational fluid dynamics (CFD) method for unsteady analysis of a series of ski jump movements with attitude changes, and to analyze the aerodynamic characteristics of an expert jumper over the entire ski jump movement. Two ski jumpers participated in this study. An IMU sensor-based motion capture suit was used to capture the jumper’s posture during the actual ski jump. A 3DCG animation was created by superimposing the joint angles obtained from the motion measurements of the 3D shape of the athlete. The unsteady aerodynamic forces acting on the ski jumper, from the takeoff to the landing phase, were then calculated using CFD simulations. A time-varying spatially uniform flow was specified as the inflow boundary condition of the computational domain. The aerodynamic simulation results indicated that both the lift and drag forces of the expert jumper increase rapidly during the initial flight phase when the jumper’s posture changes drastically. Thereafter, drag force decreased considerably, but the decrease in the lift force was less drastic. It was found to increase further in the latter half of the flight phase. An expert jumper maintained higher lift–drag ratios than the unskilled jumper throughout the flight phase.