The car exhaust gas propagation in ventilated garages represents a critical health and safety concern in modern building design! When vehicles operate in enclosed spaces, they release harmful combustion products including carbon monoxide, nitrogen oxides, and particulate matter that can quickly accumulate to dangerous levels without proper air circulation. These toxic exhaust gases initially emerge hot from the tailpipe, creating a buoyancy effect that causes them to rise before gradually cooling and mixing with surrounding air. The gas dispersion patterns are heavily influenced by the garage’s architectural layout, with potential stagnation zones forming in corners and areas with obstructed airflow. This natural propagation behavior is counteracted by strategic ventilation systems that create pressure differentials to extract contaminated air while introducing fresh air from outside. Understanding these concentration gradients and airflow patterns is essential for maintaining safe air quality levels and preventing harmful exposure to garage occupants! This is why, in our current study we try to model a car exhaust gas propagation parked inside a garage.

Figure 1: Schematic of our model

Simulation Process

The garage geometry was efficiently created using ANSYS SpaceClaim, where we accurately modeled the parking spaces, structural columns, and ventilation ducts to represent a realistic enclosed environment! The 3D model was then imported to Fluent Meshing where a high-quality polyhedra grid was generated to ensure accurate flow resolution while maintaining reasonable computational cost. For the physics setup, we implemented the species transport model to track the movement of both air and CO2 throughout the domain, enabling precise visualization of concentration gradients as exhaust gases disperse through the garage space.

Post-processing

The CO2 distribution results clearly show the exhaust gas plume forming behind the larger vehicle, with highest concentrations directly at the emission point! This localized concentration zone gradually diffuses as it moves away from the source, demonstrating how vehicle positioning significantly impacts gas dispersion patterns in enclosed garages. The visualization reveals minimal CO2 accumulation near the ceiling, suggesting that the buoyancy effects are counteracted by the overall airflow patterns in the space. Most importantly, the smaller vehicle located in the upper portion of the garage remains in a relatively clean air zone, indicating effective contaminant separation between different areas of the parking facility!

Figure 2: Co2 emission from the car in the parking space

The flow streamlines reveal complex circulation patterns throughout the garage, with notable vortex formation creating a spiraling motion that helps distribute and dilute the exhaust gases! These air currents prevent the formation of dangerous stagnation zones where pollutants could otherwise accumulate to harmful levels. The third visualization confirms that CO2 concentrations remain primarily confined to the lower right quadrant of the garage, with the ventilation system successfully preventing widespread contamination. This spatial distribution of pollutants demonstrates that strategic placement of exhaust extraction points near emission sources would be highly effective in maintaining acceptable air quality throughout the entire garage space!

Figure 3: Ventilation system remove co2 in the shortest time