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Optimization methodology employing CFD for the aerodynamic design of automotive car styling is presented. The optimization process consists of three stages: Design of Experiments (DOE), Response Surface Modeling (RSM), and optimization algorithm execution. RSM requires a number of CFD calculations in order to ensure its accuracy, making it difficult to apply the RSM to aerodynamic design optimization. In order to resolve this issue, Adaptive Multi Stage RSM (AMS-RSM) was conceived. This method provided the response surface its required accuracy and robustness. The optimization process was realized by constructing an automatic optimization system consisting of software.

When a vehicle is driven in snowy conditions, if a proper air intake design is not adopted, the snow lifted by the leading vehicles may penetrate into the engine air intake, in case of large snow ingress amount, causing a power drop. The evaluation of such risk for the intake is carried out through climatic wind tunnel tests, which cannot be conducted at the early stage of vehicle development when the prototype vehicle does not exist. In order to study that risk prior to the prototype vehicle delivery, computational fluid dynamics (CFD) which predicts the snow ingress amount accurately was established with taking into account unsteady air flow and snow accumulation. Large Eddy Simulation (LES) was used to reproduce the unsteady flow field, leading to a good agreement of the flow downstream from the snow generator with the experimental one measured by Particle Image Velocimetry (PIV). As for the snow particle behavior model, the Lagrangian method was chosen.

The following two objectives were set for the development of predictions for snow ingress into the air intake system. To enable snow ingress predictions in the design stage so that vehicles can be developed in a short period of time. To guarantee performance in very cold regions such as Canada. To achieve these objectives, it was decided to develop snow ingress prediction tools that use computational fluid dynamics (CFD). First, research was conducted in Canada to collect the snow information that was required for the simulation. In this research, snow particle measurement equipment was used to measure in detail the number of snow particles and their diameters. The research results that were obtained were reflected in the simulation, and a correlation was found between the calculations and test results obtained in Canada. Finally, tools were developed to facilitate results analysis from the snow ingress simulation.