Skin friction topology on ground vehicle models

Global luminescent oil-film skin friction meter is used to extract the skin friction topology on two generic ground vehicle models: the Ahmed body and the DrivAer model notchback configuration. Topological structures of skin friction on the top and side surfaces are extracted on both the models at different Reynolds numbers (2.68 × 10 5 , 5.35 × 10 5 , and 8.03 × 10 5 for the Ahmed body and 2.92 × 10 5 and 5.84 × 10 5 for the DrivAer model, corresponding to freestream velocities of 10, 20, and 30 m/s for the Ahmed body and 10 and 20 m/s for the DrivAer model). For the Ahmed body, important features such as forebody separation bubble, longitudinal vortex, and C-pillar vortices and vortex bursting on the rear slant angle are identified. Similarly, for the DrivAer model, in addition to separation and reattachment lines and vortex bursting, more complex vortex interactions in the rear window are revealed. Comparisons of the results obtained for both the models with existing flow visualizations and numerical results are discussed. Graphical abstract