Characterization of gas transport inside a package

Abstract: A study of a sterilizing flow in a package is done. The study is done with the commercial code Fluent using Large Eddy Simulation and validated with both Laser Induced Fluorescence and Particle Image Velociometry. The velocity field is examined in several ways; with changes in grid size, inlet conditions and sub-grid scale models. The study showed that the most important parameter is the size and form of the control volumes. A comparison with the PIV data shows that the simulations have lower velocity in the lower part of the package and more turbulent fluctuations in the whole package. The concentration study is done with two different geometries, a larger with a 7 percent larger volume than the smaller. The grids of the two geometries differs in the way that the small package has only hexahedral cell and the large package also has some tetrahedral cells in the bottom. A comparison to LIF data shows that the simulations of the small package match really well both in the top and in the bottom of the package. The simulations of the large package match well in the top but have a lower concentration level at the bottom. This could be explained by the tetrahedral cells which generate more numerical diffusion. A comparison between the large and the small package shows only a small difference of concentration over time.