Aerodynamic Drag Reduction Analysis of Race Walking Formations Based on CFD Numerical Simulations and Wind Tunnel Experiments

Drafting formations have been long recognized as highly effective for reducing drag and enhancing athletic performance, particularly in race walking events. The precise spacing and positioning of the race walkers are critical to optimizing the effectiveness of drafting. In this study, drag reduction in 15 drafting formations is investigated using wind tunnel experiments and CFD numerical simulations. The results show excellent consistency in drag reduction rate between the two methods, with differences being within 10%. This can be attributed to spacing replacing body shape differences as the primary factor influencing drag reduction. Optimal double, triple, and quadruple drafting formations produce the same results in both the wind tunnel experiments and CFD simulation, resulting in drag reductions of 67%, 66%, and 81% (wind tunnel) and 65%, 72%, and 85% (CFD). The sources of drag differences in the two methods are discussed from various aspects. The flow field obtained through CFD analysis is used to examine the mechanism of drag reduction, revealing that drafting formations have a significant shielding effect on incoming air, which reduces the number and speed of airflow impacting the core race walker. This shielding effect is identified as the primary cause of drag reduction. Using an empirical model for mechanical power output, optimal double, triple, and quadruple drafting formations enhance sports economy (4.4-5.7%), speed (3.61-4.67%), and performance (173.8-223.3 s) compared to race walking alone. The findings can serve as a reference for race walkers' positioning strategies and provide insights for considering drafting formations in various running events.