Numerical investigation of drag reduction in a Class 5 medium duty truck

In the present paper, the three-dimensional numerical investigation of Class 5 medium duty trucks (based on a production of Volvo Company) is carried out. The aim is to investigate and provide additional insights about the drag reduction methods in medium duty trucks. The flow field and pressure distribution around the truck were simulated using the Finite Volume Method. The Simple algorithm was employed to couple the pressure and momentum. A constant velocity of 30 m/s was set in the inlet, the non-slip condition in conjugation with a wall function were used on the truck and ground surfaces, and the pressure-outlet was applied at the outlet. For the turbulent regime, the well-known standard k-ε model was used to simulate the turbulent flow characteristics. The effects of vortexes around the vehicle on the drag coefficient were studied. Also, some passive devices such as standard and large windbreakers, convex roof, and the axial channel were considered for drag reduction at a high velocity (30 m/s) and standard atmospheric conditions (T=25℃, p=1 atm). The results showed that the large windbreakers and covering the gap between the trailer and the container are not suitable successors for standard windbreakers. Furthermore, it was found that the convex roof is a suitable passive or active device for notable drag reduction (25%). Some recommendations for future works might include investigating the effect of combinations of different devices on the drag reduction, studying the different underbody devices like side skirts, and using more sophisticated turbulent models such as large eddy simulation.