As part of thesis project, several investigation means were used in order to characterize the microclimate of urban spaces. Two Marseilles spaces, " Chave district including Jean Jaurès Place and Chave Boulevard " and "Cité Radieuse also named Le Corbusier Building", were selected for their urban representativeness. The results are compared to the climatic effects that they generate, known and identified as "mall", "dihedral", "stilt", "canyon" and "cover green" effects. For better understanding of thermal and aerodynamic impacts of urban forms and cover green in urban contexts and in order to simulate climatic phenomena and geometrical scenarios which can not be obtained through in-situ measurements, numerical analysis by using a solar software of simulation (SOLENE) and a Computational Fluids Dynamics (CFD) code (FLUENT) were applied to one of the two sites of Marseilles (Chave district). Thermal and aerodynamic conditions are analysed with different parameters, that are: the various urban configurations with and without cover green, dimensions and proportions of this last and finally wind directions (NW and SE in the cases of Marseilles). The cover green (limes and magnolia concentrated in the centre of the place and plane trees in the mall) is modelled with an average permeability defined as a preliminary in the form of the foliage index (leaf area index, LAI ). A comparison study is carried out between the numerical simulation results obtained by OPTIFLOW Company and in situ measurement results on the one hand and between wind speed profiles in Chave district with and without the cover green. The present paper is focused on this second numerical part of investigation. The analysis of the other investigation means, that are photographs fishes-eye and comfort index calculations, is in progress.