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Ventilation Design Handbook on Animal Research Facilities Using Static Microisolators 
4.2.3 Room Condition 
4.2.3. 1 CFD Simulations 
Two CFD models were constructed to replicate the experimental testing room scenarios as 
closely as possible. Isometric views of the two rooms are shown in figures 4.66 and 4.67. The 
overall size of the solution domain of both models was high 2.44m x 3.66m x 2.44m (8’ x 12’ x 
8’). The 0.61m x 0.57m (24” x 22.5”) centrally located radial diffuser was constructed using a 
combination of a supply and a series of planar resistances, with the loss coefficients for the 
planar resistances set such that the representation matched the available manufacturer’s data (see 
section 4.2.2). The supply was specified to provide a flow rate of 128 cfm (7.27e-02 Kg/s). 
The 0.30m x 0.30m (12” x 12”) exhaust, modeled using an extract, was located 0.20m (8”) from 
the north and west walls, and was specified to exhaust 102 cfm (5.8e-02 Kg /s). The mass 
imbalance was accounted for through a 6.4e-2m (V4”) crack at the bottom of the 0.91m x 2.13m 
(3’ x 7’) door, that was centrally located on the north wall. 
In the populated room case, the 0.61m x 0.61m x 0.81m (24” x 24” x 32”) sink, located in the 
NE comer of the room, was modeled using a solid rectangular block. The sink recess was not 
modeled. 
The shelves of the 0.61m x 1.83m x 1.52m (24” x 72” x 60”) rack were modeled using 1.27e-2m 
(0.5”) thick rectangular blocks. The top shelf was located 1 .52m (60”) above the floor, and the 
experimental shelf-to-shelf distance of 0.28m (11”) was maintained. The sides of the 0.27m x 
0.16m x 0.21m (10.7” x 6.38” x 8.39”) shoebox cages were modeled using thin plates, with 
conductivity and thickness of the plate set to that of the polycarbonate. The water bottle in the 
cage was constructed from a series of rectangular blocks and triangular prisms: the volume of the 
water bottle was maintained compared with the physical bottle. The rack was modeled as a 
planar resistance, with the loss coefficient set to 0.25, corresponding to a free area ratio of 0.85 
(Idelchik (1989)). The heater was modeled using a fixed flux rectangular block, with the block 
specified to dissipate 2.42 W. The diffuser stones were modeled using volume sources, with the 
injection rate of the CCF concentration set to 990 mL/min (3.01 E-5 kg/s) total, or 7.86 mL/min 
per cage (2.39 E-7 kg/s). 
