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In order to fulfill the need for an efficient and reliable computational method for the aerodynamic optimization of passenger cars, a numerical simulation strategy has been developed at DaimlerChrysler in Stuttgart. The simulation strategy consists of surface preparation, three dimensional mesh generation, flow simulation using CFD, and post-processing. The method will be applied mainly in the early concept phase of the development process when 1:4 scale models with smooth underbodies are used. In this study SAE-bodies as well as modifications of real car shapes are presented. The paper also discusses which improvements are needed to establish a mainly CFD-based process in the early concept phase.

This paper compares numerical results of the flow through an axial fan with measurements. A typical nine bladed engine driven fan is modeled using grid refinement techniques in order to maintain good resolution at the fan blades while also including the extent of the test fixture. In the calculations a multiple reference frame approach, a transient moving mesh and a body force model are investigated. At a fixed fan speed discharge and pressure rise were measured in the test facility and a series of numerical simulations were made over the same range of conditions. A comparison of the two discharge curves shows fairly good agreement.