Evaluation of modified body force (MBF) model for rapid air flow modeling through perforated tiles

Perforated floor tiles are used to supply cooling air from a subfloor pressurized plenum to server racks in raised floor data centers. Consideration of momentum rise due to acceleration of air through pores is critical for correctly predicting the flow field downstream of a perforated tile. The momentum rise could be captured by either directly resolving the tile pore structure (geometrical resolution model, GR) or simulated by artificially specifying a momentum source above the tile surface (modified body force model, MBF). Artificial specification of the momentum source obviates the need of resolving the tile pore geometry and hence requires considerably lower computational effort. In our previous investigation, we showed close agreement between the MBF and the GR model for different pore sizes, porosities and edge blockages. In this paper we further evaluate the MBF model for different pore patterns, air flow rates, tile thickness, small pore sizes, anterior blockage and presence of an adjacent server rack. From the GR model, it was observed that the flow field was very similar for staggered and aligned pores and for the range of air flow rates investigated. Thicker tiles resulted in lower pressure loss and lower air entrainment in the downstream. Small tile pores resulted in minimal excess downstream momentum and hence very low air entrainment. Anterior dampers increased the tile pressure loss but had negligible effect on air entrainment. MBF model was able to capture the trends predicted by the GR model and a close agreement between the two models was obtained. MBF model showed promise for modeling complex tile geometries with significantly lower computational effect.