This is a partial model for models that describe the bi-directional air flow through large openings.
Models that extend this model need to compute
mAB_flow
and mBA_flow
,
or alternatively VAB_flow
and VBA_flow
,
and the face area area
.
The face area is a variable to allow this partial model to be used
for doors that can be open or closed as a function of an input signal.