A windcatcher is a structure for providing natural ventilation using wind power; it is usually fitted on the roof of a building  to exhaust the inside stale air to the outside and supplies the outside fresh air into the building interior space working by pressure difference between outside and inside of the building. In this paper, the behaviour of free wind flow through a  three-dimensional room fitted with a centred position  two-canal bottom shape  windcatcher model is investigated numerically, using a  commercial computational fluid dynamics (CFD) software  package and LES (Large Eddy Simulation) CFD method. The results have been compared with the obtained results for the same model but using RANS (Reynolds Averaged Navier-Stokes) CFD method. The model with its surrounded space has been considered in both method. It is found that the achieved results for the model from LES method are in good agreement with RANS method’s results for the same model.