Abstract
Keywords: aerodynamics, wheel, flow field
The aerodynamics regarding to road vehicles plays a crucial role recently, as aerodynamic drag influences fuel consumption, and thus pollutant emission significantly. To find the optimal vehicle shapes besides keeping the overall style of the individual cars, the aerodynamic possibilities to reduce drag seem to reach their limits in terms of body shape optimization. Basic low-drag body shapes were developed during the last few decades and following the age of invisible aerodynamic optimization of high-drag-looking, but well styled vehicles (Hucho, 1998). The effect of rotating wheels exposed to a free stream, or being partially covered by the car wheelhouse, leads to a dramatic increase in drag coefficient through mechanisms that are still not fully understood. Also wheels influence mud deposition on the vehicle body (Lajos et al. 1984) and are important elements of the under-body flows (Wiedemann, 1996, Lajos, et al. 1988). The contribution of the wheels and wheelhouses to the total aerodynamic drag and lift of a modern car is around 30% and 40%, respectively (Wickern et al., 1995, Eloffson et al., 2002, Merker et al., 1992). Road vehicles, especially their wheels and wheelhouses are bluff bodies, characterized by large regions of flow field influenced by boundary layer separation. The resultant flow field is a complex, 3D flow field. The Reynolds number is in the order of 8 · 105, thus transition occurs far upstream from the wheelhouses so the flow is handled to be turbulent. The fluid can be regarded as incompressible and isothermal.