Validation of computational fluid dynamics applied to aerodynamic flows in sport with specific application to cycling

In sports engineering, computational fluid dynamics (CFD) is increasingly being used to analyse external aerodynamic problems. CFD, with its ability to output many flow parameters, often reveals a great deal more than wind tunnel testing. However, when working with such complex software, how confident can the user be in the accuracy of the results? This paper presents the first stage of CFD validation in which the ultimate aim is to decipher a model that can be used for analysing the flow around a bicycle and rider. A CFD validation of an external aerodynamic flow around a sphere and cylinder was carried out. A number of mathematical models are compared. The models tested gave very contrasting results, emphasising the importance of understanding the accuracy of each model. The evolution of the CFD model validation and how it will be used to evaluate the aerodynamics of a full bike and rider is explained. It is hoped that this work can form some sound justification for future CFD models used to investigate aerodynamic flows in cycling and other sports.