The present article deals with an experimental and numerical investigation of heat and mass infiltration rates during the opening of a refrigerated truck body. Experiments were carried out for different temperatures and different aperture ratios. The infiltration dynamics was found to involve two distinct phenomena: a buoyancy driven flow and a boundary layer flow. The first is a density-driven flow which gives birth to an important heat load peak. The second phenomenon is due to quasi steady-state natural convection over the inner wall of the truck. In the present work, the infiltration phenomenon was first analysed by means of a computational fluid dynamics model. The infiltration flow rate is well predicted except at the transition between both flow regimes. An analytical model using the ideal flow theory was also developed to model the buoyancy driven flow. The natural convection boundary layer flow is then well predicted using a classical method.