A shape-control methodology for vehicle aerodynamics based on sectional parametrization

This study proposes a novel parametric vehicle design framework based on 2D contour geometry to overcome the limitations of conventional aerodynamic analysis models. The widely used Ahmed model suffers from limited geometric fidelity, while the DrivAer model presents difficulties in systematic shape modification and parameter control. To address these issues, the proposed approach enables both physically realistic aerodynamic representation and flexible geometric parameterization within a unified framework. A 3D vehicle geometry is constructed by extruding and integrating parameterized 2D contours derived from the front, top, and side views, allowing compact yet expressive shape control through a limited set of design variables. Computational fluid dynamics (CFD) simulations are performed to validate the aerodynamic accuracy of the generated geometries, yielding drag coefficient errors of 2.31%, 2.44%, and 6.84% for the fastback, notchback, and estate configurations, respectively, relative to the experimental DrivAer data. Parametric investigations reveal that roofline height is the most influential design parameter governing aerodynamic drag characteristics. Furthermore, detailed flow field analyses elucidate the evolution of wake structures and pressure distributions as functions of key geometric variations. The proposed methodology provides a computationally efficient and scalable framework for aerodynamic shape optimization in early-stage vehicle design and is readily extendable to other bluff-body aerodynamic applications.