A Comparison of the Wake Structures of Scale and Full-scale Pedalling Cycling Models

Abstract

This paper presents a novel approach to better understand the unsteady aerodynamics associated with a dynamically pedalling cyclist. Using high resolution Particle Image Velocimetry (PIV) in a water channel, the large-scale wake structure is analysed for various phases of the crank cycle of a 1:4.5 scale-model cyclist/bicycle under both static and pedalling conditions. Both quasi-steady and dynamic pedalling leg results are compared with detailed velocity field surveys made in the wake of a full-scale pedalling cyclist mannequin of similar geometry and position in a wind tunnel. A time-averaged and phase-averaged analysis of the various flow regimes that occur throughout the pedal stroke shows good agreement between scale-model and full-scale mannequin investigations. This highlights the robustness of the formation of the primary wake flow structures when subjected to varying Reynolds number, bicycle/rider geometry and quasi-steady/dynamic pedalling conditions.