Measurements of air flow velocity using Particle Imaging Velocimetry (PIV) were undertaken in a closed enclosure representing a model of domestic refrigerator (scale 1) in which mainly natural convection occurs. This transfer takes place between one cold vertical wall and the other walls, which are exposed to heat losses. Numerical simulations using CFD software were undertaken in this model assuming a constant cold wall temperature (evaporator) and laminar 3D-flow. The numerical simulations also take into account heat transfer by radiation between walls. The influence of the temperature and the dimension of the cold wall were studied. We show that the temperature of the cold wall has more influence on the air flow than its dimensions. The thickness of the hydrodynamic layers were calculated from PIV velocity measurements. In spite of some differences at certain positions, the results obtained with numerical simulations are in relatively good agreement with the air flow field measured with PIV technique.