I can appreciate the technical aspects of this topic, but over time have gotten to the point that I prefer the more direct route of practical application because there are so many variables that can effect individual outcome.
In my experience--humidors 4 ft or less I put the active humdifier on the bottom with a fan in the upper area to help balance out if the humidor is tightly packed. 5 ft still on the bottom, but put another outlet higher up so the humidifiers can be moved up easily if the top is too dry. Fans on top. 6 ft & taller- main humidifiers on the bottom of the upper compartment with small humidifier on the bottom of the lower compartment. Fans on top of main compartment & fan at the top of bottom compartment.
May or may not agree with the theoretical, but seems to work for most people.
cheers,
Bob Staebell