The present paper introduces the impact of the turbulence model and the meshing effect on the airflow characteristics inside a square duct. The analysis in this study is done with the commercial software "ANSYS FLUENT 17.0" using the finite volume method. In this application, several numerical parameters such as the convective heat gain, the magnitude velocity, the temperature, the static pressure and the turbulence characteristics are analysed in order to select the most appropriate model. To ensure the accuracy of the numerical findings, we investigated the influence of meshing on CFD results in order to select the most appropriate mesh with the shortest calculated time. We also looked on the impact of the turbulence model on the aerodynamics properties of the considered square air duct.