Assessment of Drag Reduction Devices Mounted on a Simplified ‎Tractor-Trailer Truck Model

Document Type : Research Paper


School of Computing and Engineering, College of Science and Engineering, University of Derby, Derby, UK


Aerodynamic drag reduction of tractor-trailer combination trucks is critically important to improve their fuel consumption which consequently results in lower emissions. One practical method to reduce aerodynamic drag of a truck is by mounting drag reduction devices on the truck. This paper presents a numerical study of turbulent flow over a simplified tractor-trailer truck with different drag reduction devices mounted on the truck using the Reynolds Averaged Navier-Stokes (RANS) approach to assess the effectiveness of those devices in drag reduction around the tractor-trailer gap region. Three cases with different drag reduction devices have been studied and significant drag reduction (above 30%) has been achieved for all three cases. Detailed analysis of the flow field has been carried out to understand drag reduction mechanisms, and it shows that no matter what drag reduction devices are deployed the drag reduction is mainly due to the reduced pressure on the front face of the trailer, and a small proportion of the drag reduction is due to the reduced turbulent kinetic energy in the gap region.


Main Subjects

[1] Bearman, P., Bluff Body Flow Research with Application to Road Vehicles, In: Browand, F., McCallen, R., Ross, J., (eds) The Aerodynamics of Heavy Vehicles II: Trucks, buses and trains. Springer, 41, 2009, 3-13.
[2] Abikan, A., Yang, Z., Lu, Y., Computational Analysis of Turbulent Flow over a Bluff Body with Drag Reduction Devices, Journal of Applied and Computational Mechanics, 6(SI), 2020, 1210-1219.
[3] Bradley, R., Technology Roadmap for the 21st-Century Truck Program, Report for the US Department of Energy, Washington DC, Report no. 21CT-001, 2000.
[4] Charles, T., Lu, Y., Yang, Z., Impacts of the Gap Size between Two Bluff Bodies on the Flow Field Within the Gap, Proceedings of the 13th International Conference in Heat Transfer, Fluid Mechanics and Thermodynamics, Portorož, Slovenia, 132-135, 2017.
[5] Charles, T., Yang, Z., Lu, Y., Numerical Analysis of Flow in the Gap between a Simplified Tractor-Trailer Model with Cross Vortex Trap Device. International Journal of Mechanical and Mechatronics Engineering, 13(11), 2019, 707-711.
[6] Hjelm, L., Bergqvist, B., European Truck Aerodynamics – A Comparison Between Conventional and CoE Truck Aerodynamics and a Look into Future Trends and Possibilities. In: Browand, F., McCallen, R., Ross, J., (eds) The Aerodynamics of Heavy Vehicles II: Trucks, buses, and trains, Springer, 41, 2009, 469-477.
[7] Yang, Z., Large-Eddy Simulation: A Glance at the Past, a Gaze at the Present and a glimpse at the Future, the 5th International Symposium on Jet Propulsion and Power Engineering, Beijing, China, 2014-ISJPPE-0010, 2014.
[8] Worth, N., Yang, Z., Simulation of an Impinging Jet in a Crossflow Using a Reynolds Stress Transport Model, International Journal for Numerical Methods in Fluids, 52, 2006, 199-211.
[9] Ostheimer, D., Yang, Z., A CFD Study of Twin Impinging Jets in a Cross-flow, The Open Numerical Methods Journal, 4, 2012, 24-34.
[10] Yang, Z., Assessment of Unsteady-RANS Approach against Steady-RANS Approach for Predicting Twin Impinging Jets in a Cross-flow, Cogent Engineering, 1, 2014, 936995.
[11] Daly, B.J., Harlow, F.H., Transport Equations in Turbulence, Physics of Fluids, 13, 1970, 2634-2649.
[12] Gibson, M.M., Launder, B.E., Ground Effects on Pressure Fluctuations in the Atmospheric Boundary Layer, Journal of Fluid Mechanics, 86, 1978, 491–511.
[13] Allan, J., Aerodynamics drag and pressure measurements on a simplified tractor-trailer model, Journal of Wind Engineering & Industrial Aerodynamics., 9, 1981, 125-136.