Opel utilizes a CAE database which allows the engineers to quickly extract components, such as the base chassis, external mirrors, and spoilers, and combine them into a CAD model. The pre-processing software ANSA is then used to produce a triangular surface mesh. Generation of the volume mesh is done using a variety of tools including Fluent's TGrid and GAMBIT mesh generators. Prism layers are utilized to provide good resolution of the viscous boundary layer and the remaining volume is filled with tetrahedra. Non-conformal interfaces are used to handle difficult geometry such as external mirrors, underbody, and side window steps.

Pressure distribution and pathlines around the Opel Astra vehicle
Courtesy of Opel AG and Fluent

Visualization of the predicted flow field allows the Opel engineers to evaluate the aerodynamics of the car's components long before a physical model is constructed. In the future, Opel engineers hope to increase model complexity and solution accuracy, as well as, add additional capabilities such as aeroacoustics and water management.