Automotive aerodynamics depend on the flow around a vehicle for performance, efficiency, and stability. Vehicles create airflow patterns with high and low pressure, boundary layers, and wake zones. The vehicle’s top, sides, and back have lower pressures and potential flow separation than the front, which compresses oncoming air. Engineers reduce drag by streamlining the vehicle, reducing frontal area, and regulating airflow separation. They optimize downforce to improve stability and handling at high speeds, especially in high-performance automobiles. These flow patterns are seen and analyzed using CFD models and wind tunnel testing to help designers choose vehicle shapes and features. Consequently, we conducted a CFD study on the flow around the vehicle with a focus on aerodynamics.

Figure 1: Real KIA Optima car, adopted from Wikipedia

Simulation Process

The simulation requires preliminary steps, including designing the car model and producing a suitable mesh grid concentrating on smaller cells near the vehicle. This process leads to the generation of 2696284 elements, both polyhedral and cut-cell. The wind turbine applies 90km/h wind speed.

Figure 2: combination of polyhedral and cut-cell grid

Post-processing

Comprehensive information about the vehicle’s aerodynamic performance is provided by the CFD modeling of the flow around it. Effective airflow management is indicated by the pressure contour, which shows a high-pressure area at the front and low-pressure sections above the hood and roof. While a considerable low-pressure zone behind the vehicle predicts a reasonably small wake, its streamlined design limits pressure changes along its sides. With a modest upward push, the design’s aerodynamic efficiency is indicated by the lift coefficient (Cl) of 0.17 and the drag coefficient (Cd) of 0.29. These results are corroborated by the wall shear stress contour, which displays higher stress locations with values as high as 12.4 Pa along the leading edge of the hood, the windshield, and the front edge of the roof. Most of the body’s lower stress zones, shown in blue, indicate easy airflow. The impact of side mirrors and A-pillars on overall aerodynamics is accentuated by localized high-stress locations. When taken as a whole, these evaluations show an aerodynamic profile that has been well-optimized to balance drag reduction with useful design considerations, improving the vehicle’s performance and efficiency.