A humidor, for the most part, is a small enclosure, with lots of dead spaces where moisture can collect, along with walls of Spanish cedar that are moisture sinks.. Being an enclosed system, the various molecules are going to attempt to set up an equilibrium in which all molecules are evenly distributed. Also, the hygroscopic nature of the cigars is going to have the effect of pulling moisture from the surrounding air, causing some interesting diffusion and Browninan effects. There is also a hydrogen bonding issue in play (water likes to stick to itself), causing vapor to concentrate.
Thus, the model of air circulation in an ideal environment may not apply very well to individual humidors, as there are many convoluting effects taking place in this small space.
My advice is to rotate your cigars fairly frequently, as the big issue that you will face is that moisture will get trapped in low air flow zones, and those high humidity pockets are where mold will tend to form.