Transient aerodynamics of vehicle platoons during in-line oscillations

Wind tunnel experiments were performed to study the transient aerodynamic forces experienced by two four-vehicle platoons when one of the platoon members was forced to undergo in-line oscillations. The longitudinal forces acting on all vehicles in the platoon were determined simultaneously during the oscillations. The effects of the position of the oscillating vehicle, the shape of the vehicles, and the displacement and velocity amplitudes of the oscillation were examined. Significant drag changes were observed on the immediate neighbors of the oscillating vehicle. The drag variations strongly depended on the relative position between the oscillating vehicle and its adjacent neighbors, as well as the shape of the vehicles. Drag measurements under steady-state conditions showed similar results to the transient investigations. A cavity drag model was used to explain the results.