RANS-based aerodynamic optimization of a pickup truck: performance assessment and verification of add-on improvements

Pickup trucks represent a significant share of the global automotive market, yet remain characterized by poor aerodynamic efficiency due to their inherent bluffbody geometry. This study investigates the aerodynamics of a generic double-cab pickup truck, in two configurations: the open and closed bed, using a steady-state RANS turbulence model and wind tunnel validation. Three turbulence models, Realizable k − ε, Lag EB k − ε, and SST k − ω were evaluated against experimental data to determine the most accurate approach for predicting drag trends across configurations. The Lag EB k−ε model demonstrated superior fidelity in predicting ∆CD trends and was selected for the baseline flow topology study and optimization phases. The baseline flow topology analysis identified various critical sources of drag and the generation of a distinct pair of counter-rotating vortexes that negatively impacts the drag generation. Several aerodynamic add-on devices were designed and assessed, including a sealed cabin-bed gap, a shortened tailgate, and a rearcab spoiler. Results indicate that sealing the cabin-bed gap yields a drag reduction of approximately 2.0%. The optimal configuration, combining the gap seal with the spoiler, achieved a drag reduction of 3.2% for the open bed configuration and 2.4% for the closed bed configuration. These findings demonstrate that targeted management of the cabin wake and gap flow can significantly mitigate form drag without altering the primary vehicle architecture.