As seen in the figure, there are four big circular airflow patterns
in the plenum, two located in the perimeter, and two located in the
interior part. The air that comes out from the small holes is split
into two parts, one turning toward the perimeter and the other
toward the interior. For configuration #1 the air temperature
through diffuser 1 and 10 was lower (see Fig. 5). The explanation
of this phenomenon is clearly visible in Fig. 6. The two strong airflow
patterns turning to the interior part of the plenum, directly
feed diffusers 1 and 10, keeping the air temperature lower for these
two.