Numerical and experimental study on flow and diffusion field in room.

Turbulent flow fields of velocity and diffusion in several types of mechanically ventilated rooms are precisely analyzed both by model experiment and by numerical simulation based on the k-s two-equation turbulence model. The detailed analyses of contaminant diffusion by simulation make it possible to comprehend clearly the structures of velocity and diffusion fields in rooms. The flow fields in such rooms, as analyzed here, are mainly characterized by the inflow jet and the rising streams around it. The combination of one jet and rising streams forms a 'flow unit.' The total velocity field and the resulting diffusion field of contaminant in a room are well modeled as serial combinations of these 'flow units.' Room air distribution is greatly affected by the arrangement of supply openings and, possibly, exhaust . openings. The influence of those arrangements on the flow fields is studied. When the number of supply openings is decreased, the flow units corresponding to the eliminated supply openings vanish and the remaining flow units expand. A change in arrangement or in the number of exhaust openings hardly affects the entire flow field; however, such changes often have a large influence on the contaminant diffusion field. Apparatus placed in a room has a great influence on the flow field. The air flow distribution and the contaminant diffusion field in the room with flow obstacles in various arrangements are also analyzed. On the whole, the influence of flow obstacles on the entire flow field is limited to a certain degree, however, the influence on the 'flow unit' is significant.