External and internal CFD analysis of a high-speed human powered vehicle

Human powered vehicle competitions provide a stimulating research field aiming at the development of high‑efficiency and sustainable means of transportation. Aerodynamic studies about top-speed bicycles, even if classified as sport engineering, are able to increase the knowledge also for the design of their commuting version such as three-wheeled velomobiles. In the present paper, some of the design and manufacturing features that play a key role in the aerodynamic performance of such vehicles are discussed. Then, a critical review of a case study prototype is presented and five CFD models of the same vehicle are compared and discussed. In particular, two aspects are investigated and quantified in terms of power loss: the negative effects of surface discontinuities on the laminar-turbulent transition of the boundary layer and the crucial role of wheel-wells for a properly working internal ventilation.