The Effect of Distances between the Vehicles on Their Fuel Consumptions in Highways

Currently, the cars fuel consumption and resulting pollution from this consumption are reasons which encourage endeavors for optimizing fuel usage. One of the main aerodynamic characteristics that heavily affect fuel consumption is the drag force on vehicles. By reducing drag forces, the effective loads on cars are reduced and thus the fuel consumption is diminished. One of the interesting problems associated with drag calculations is the inter-vehicle spacing of vehicles on highways that directly affect the applied forces on car bodies. In this paper, a numerical simulation of three dimensional turbulent flow around a series of vehicles moving in the same lane with varying distances was developed using the commercial fluid dynamic CFD software FLUENT. The study focuses on CFD based drag predictions on two and three dimensional computer models and the results related to the corresponding fuel consumptions. The spacing effects in front and behind the vehicles are studied in steady conditions with different speeds and distances. The RNG k-ε turbulence model was adopted for the calculations and consistent results were found.