Computational fluid dynamics (CFD) is a popular tool in the design and optimization process of vehicles. Reliable numerical models of the vehicle aerodynamics should resolve basic features of the flow around the vehicle under investigation without any fitting procedure. On the other hand, the simulations should be economical, i. e. long computing times and high memory requirements should be avoided. In our contribution, numerical simulations of the flows around the Ahmed reference car body based on the unsteady Reynolds-averaged Navier-Stokes (URANS) equations are presented. The Ahmed body is a simplified car used in automotive industry to investigate the influence of the flow structure e. g. on the drag. The flow around the Ahmed body exhibits basic features, which are also characteristic for other bluff body vehicles, namely trucks, buses or trains: There exist large coherent vortex structures and elongated separated flow regions downstream of the Ahmed body. The vortices, the detached flows, and the boundary layers at the body contours interact strongly, these interactions are of fundamental importance for aerodynamical parameters of the car. In our study, Ahmed bodies with different rear geometries (slant angles phi of 25 deg and 35 deg) are investigated. The findings from the numerical simulations are in agreement with corresponding experiments. Based on the numerical data, we give an explanation of the basic mechanisms of the unsteady flow behavior.


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    Title :

    Unsteady RANS simulations of flows around a simplified car body


    Additional title:

    Instationäre RANS-Simulationen der Strömungen um eine vereinfachte Karosserie


    Contributors:


    Publication date :

    2009


    Size :

    10 Seiten, 9 Bilder, 2 Tabellen, 15 Quellen


    Type of media :

    Conference paper


    Type of material :

    Print


    Language :

    English




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