On the effects of crosswinds in tandem aerodynamics: An experimental and computational study

Aerodynamics has been an important research aspect in cycling science, with aerodynamic apparel and equipment, athlete postures, and race strategies all taking advantage of scientific aerodynamics knowledge. Crosswinds occur when cyclists travel at a non-zero angle to the direction of the wind. Research into crosswinds has yielded race strategies for able-bodied cyclists such as staggered drafting, and wind conditions are recognised as a key factor to consider for cyclist safety. The impact of crosswinds on tandem para-cyclists is less understood. Within the tandem para-cycling discipline, two athletes compete as a team on a single bicycle with a high degree of flow interaction between both athletes. Wind tunnel experiments and computational fluid dynamics were utilised in this research to investigate the drag and lateral forces at yaw angles between 0°–20°. No single turbulence model was found superior for all yaw angles investigated, with the SST k-ω and k-kl-ω turbulence models providing good results for separate yaw ranges. The individual drag and lateral forces experienced by both athletes and the tandem bicycle were investigated to provide further clarity on the distribution of wind loads for each yaw angle tested, and to aid in identifying potential locations for aerodynamic optimisation. 15° yaw was found to be the critical yaw angle where the maximum drag area of 0.337 m² was experienced. The lateral force exceeded the drag force by 52.8% at a yaw angle of 20°.