A newly developed computer code, FONS-AERO, is used to simulate the flow parameters of a carrier gas and an aerosol in an idealized vented containment during a blowdown. The code is a transient, multidimensional turbulent flow code that can handle gas and aerosol flows simultaneously under various flow situations. Complicated boundary conditions can also be readily incorporated. Some initial results of aerosol distribution in the containment and sensitivity to aerosol types are presented.