CFD simulations of spoked wheel aerodynamics in cycling: impact of computational parameters

Spoked wheels are commonly used in cycling races and their aerodynamic performance is a critical factor in the overall cycling performance, as the wheels can be responsible for about 10% of the total cyclist-bicycle drag. Although several computational fluid dynamics (CFD) simulations have been carried out for wheel aerodynamics in the past decades, it is still not clear to which extent the outcome of such simulations is sensitive to the computational parameters set by the user. The present paper aims at defining a framework for CFD simulations of an isolated spoked wheel by a systematic sensitivity analysis focused on the computational grid, wheel rotation modeling and turbulence modeling. The results show: (i) a high sensitivity to the wheel surface grid, y⁺ (<4) and far-field growth rate (≤1.15); (ii) the wheel rotational approaches with moving reference frame (MRF) and hybrid MRF-RW (RW ​= ​rotating wall approach) can provide a satisfactory agreement with wind tunnel data available in the literature (+9.7% and −2.1% deviations, respectively); (iii) k-ω SST, γ-SST or realizable k-ε are suitable as turbulence models. This work is intended to stimulate the accurate and reliable application of CFD for the assessment and optimization of wheel aerodynamics.