Evaluation of aerodynamic drag of a full-scale cyclist model by particle tracking velocimetry

Abstract

Large-scale particle tracking velocimetry is conducted in the wake of a full-scale cyclist model at 14 m/s. Particle tracks are measured in a volume of 100 x 162 x 5 cm3, from which the velocity statistics are computed. The aerodynamic drag is evaluated using the control volume approach invoking the conservation of momentum. The drag obtained from the PTV measurements closely matches that measured by an external force balance. Furthermore, it is shown that the drag force is largely due to the streamwise velocity deficit, whereas the contribution of pressure and Reynolds stress terms is minor. Finally, the drag distribution in a cross-flow plane is used to identify three regions of large velocity deficits suited for future drag minimization: the lower legs and feet, the streamwise vortical structures and the separated region over the lower back.