CFD simulations of an isolated cycling spoked wheel: The impact of wheel/ground contact modeling in crosswind conditions

As both cycling wheels can constitute up to 10% of the total drag of the cyclist–bicycle system, care is required for accurate modeling of the wheel aerodynamics. This short communication extends the results of an earlier study in which the impact of the presence of the ground and the type of wheel/ground contact modeling on the wheel aerodynamic resistance was studied. In CFD, two types of wheel/ground interaction can be considered, either a small clearance between wheel and ground or a solid step replacing the contact patch. Previous CFD simulations – without crosswind – suggested to limit the distance between wheel and ground to maximum 20 mm, whereas the step height should be maximum 10 mm. New CFD simulations have been performed including the effect of crosswind, and validated with WT tests. These indicate that the clearance between wheel and ground should be maximum 10 mm, lower than without crosswind, whereas the step height should be smaller than 10 mm. Flow field visualizations are provided to elucidate the flow behavior around a spoked wheel in crosswind conditions. This study is intended to help researchers and manufacturers in the selection of best approaches to accurately reproduce the wheel aerodynamics when crosswind is present.