Experimental study on the flow and particle transport induced by the interaction between down wash air flow and moving object in mini-environments

In this study, we experimentally investigate the flow field and particle transport induced by the interaction between the downwash air flow and moving object in a mini-environment having perforated-floor with different porosities. The flow visualization shows that a vertical flow in the rear side of the moving object is formed due to the interaction between air flow, moving object, and rebounded flow from the porous perforated-floor. The effect of the resultant flow on the particle behavior is examined under the cases of with and without a particle source in the mini-environment. The measured results indicate that particle numbers collected from the top and rear sides of the moving object increase with the increase of moving object velocity for the no particle source case. For the flow field with particle source case, the measured results show that particle numbers collected from the top and rear sides of the moving object decrease with the increase of moving object velocity. Because higher amount of particle can be carried away through the high porosity perforated-floor, the measured particle collection results indicate that lower particles were collected when higher porosity perforated-floor were used for both with and without particle source.