Simulation and Estimation of CO<sub>2</sub> Emission and Concentration in the City of Douala: Case of Campus A, University of Douala-Cameroon

Douala-Cameroon is a growing city with huge number of cars and motorcycles plying the roads, especially during rush hours. These automobiles emit exhaust gases, leading to atmospheric pollution. By simulating and measuring the concentration of carbon dioxide (CO2) gives a view of the quality of air consume around and within the University of Douala main campus. The study involved both experimental and numerical models developed for atmospheric pollution dispersion in street canyons. A computational fluid dynamics (CFD) simulating software, FLUENT version 6.3.26 in combination with a grid generating preprocessor GAMBIT version 2.4.6 and a post processor Tecplot version 08 for animation and visualization of results were employed for simulations. The computational domain is discretized with unstructured triangular cells. Measurements were done during the morning and evening rush hours, using the gas tester, KIMO-KIGAZ 700 (060322). For both simulated and measured data, the model named Campus led to the maximum concentrations, while the model named BATI led to the minimum concentrations (3.09 and 1.35), (2.53 and 0.34) respectively. This high concentration is proportional to the number of buildings per model and it is advised that during rush hours occupants of this stretch of buildings should take necessary majors to avoid developing respiratory health challenges. Average total CO2 emission is estimated at 143.2 kg/rush period, with motorcycles contributing highest (75.8 kg/2h) and cars (67.4 kg/2h). The results indicate that, motorcycles significantly affect air quality in urban cities.