Computational fluid dynamics simultations of flow and dispersion in the aerosol test chamber

This report presents findings from computer simulations of the air flow and the dispersion of aerosols inside a rectangular 12 m3 Aerosol Test Chamber. Methodologically, the Large Eddy Simulation approach is used, in conjunction with both a scalar (Eulerian) and a discrete (Lagrangian) aerosol model. In the context of these two approaches, the Stokes number is discussed. Also, computations of dimensionless frictional l+ distance values are reported, to check the adequacy of the mesh resolution. Furthermore, the report focuses on velocity data and dispersion results. It seems that the Large Eddy Simulation approach is well suited for investigations of the flow and dispersion in the Aersol Test Chamber. From an operational point of view, the findings of the present study suggest that the chamber does not seem optimal for studies of long-term effects (i.e. hours or more) of external conditions on aerosols, because of the decay of aerosol concentration, which is unavoidable due to gravitational settling, air circulation, particle deposition, or a combination of these factors. Moreover, the results suggest that the design of the feedback control loop responsible for controling the aerosol injection into the chamber must be considered thoroughly in order to strike a good balance between obtaining stable concentration values as well as sufficient mixing in the chamber. Also, experimental measurements conducted in the chamber must be carried out in a particularly careful manner, if statistically valid experimental data are desired.