ETUDE DES EFFETS DE LA REFRACTION EN MILIEU AXISYMETRIE 2D. APPLICATION A LA TOMOGRAPHIE DANS LES ECOULEMENTS EN PHASE GAZEUSE

摘要

This work deals with a numerical simulation and a visualisation the refraction effects in axisymmetric 2D refractive index field. The study has been realised with a heated horizontal disk surrounded by air in free convection. The first step is the computation of the temperature and the refractive index fields using a numerical model which based on the resolution of Navier-Stokes equations coupled to the equation of the energy. The second step is consecrated to the calculation of the path ray travelling the media through a multitude elementary diopters localised by the isotherms. The originality of our work is to take account of the totality phenomenon, thermal and optic, in all the environment of the disk without disregarding effects of edge. The confrontation of the model with the experimental observation shows a good agreement and explain the existence of a caustic induced by the thermal boundary layer which plays the role of a lens.