Numerical analysis on effect of vehicle length on automotive aerodynamic drag

Effect of vehicle length on automotive aerodynamic drag was studied by computational fluid dynamics for changed MIRA model. Vehicle models with different length were established whose engine hood in the front, luggage in the tail and wheelbase were lengthened respectively or simultaneously in case of same overall styling, corresponded to three lengthening methods. Then aerodynamic characteristics of theirs were analyzed and compared. The result showed that aerodynamic drag was obviously decreased with the increase of length in the front and tail of the models. Models which were lengthened in the front and in the tail at the same time through reasonable lengthening combinations had a lower drag coefficient. In addition, drag coefficient would become higher gradually with the growth of the vehicle wheelbase.