INVESTIGATING INFLUENCE OF SLANT ANGLES ON AERODYNAMIC PERFORMANCE OF HEAVY-DUTY BUSES (HDB) THROUGH COMPUTATIONAL FLUID DYNAMICS (CFD)

Abstract

Heavy-duty buses (HDBs) play a vital role in public transportation systems; however, their blunt body geometry results in significant aerodynamic drag, leading to high fuel consumption. Traditional experimental methods for evaluating HDB aerodynamic performance are time-consuming, resource-intensive, costly, and limit the number of design configurations that can be studied. Therefore, this study employs computational fluid dynamics (CFD) to analyse the impact of different slant angles on HDB aerodynamic performance and assesses the reliability of CFD predictions by comparing them with published experimental data. A three-dimensional bus model was created using ANSYS Design Modeller, and numerical simulations were conducted in ANSYS Fluent under appropriate boundary conditions. The rear tilt angle was systematically varied to investigate its effect on the drag coefficient. Results indicate that the rear tilt angle significantly influences aerodynamic drag, with the drag coefficient reaching its minimum at a 12.5° tilt angle. Furthermore, CFD calculations showed good agreement with experimental results, with deviations consistently below 6%. These findings validate CFD as a reliable and cost-effective tool for predicting the aerodynamic performance of heavy-duty buses.