This paper presents a study of the aerodynamical forces and moments encountered by a close-proximity platoon of Heavy Goods Vehicles (HGVs) undergoing overtaking manoeuvres. From a series of wind tunnel experiments and moving model experiments, evidence is presented of a complex relationship between the drag and side force coefficients of the platoon, contrasting with an equivalent single lorry. This includes the potential of interactions akin to hysteresis. The benefits of these interactions on both the individual lorries and the platoon as a whole are discussed and explained, demonstrating the advantages/disadvantages of platooning techniques. Furthermore, the unsteady forces on a single overtaken lorry are considered for both the static and moving case.
Soper et al. (Wed,) studied this question.