A major aim within the CVD (Chemical Vapor Deposition) field is to obtain homogeneous depositions which necessitates a good gaseous flow inside the reactor. However, design of industrial reactors was empirical for a long time and the quality of the flow was not optimized. For these reasons, the current trend is to develop models to describe flow in experiments ([1] to [5]). In this paper, a visualisation of flow concerning deposition of aluminium nitride in a LPCVD reactor is presented. We have adapted a program code to our experimental apparatus.