Distance between a box fan and a perforated plate

[nomisme]

I have a question about the relationship between fan CFM vs the distance it is installed away from a perforated wall.
I did a simulation and it shows that keeping a distance between the two will make the fans have more CFM, less static pressure than the fans directly installed on the plate.
If doing so is beneficial, why do so many people install their fans directly on top of it?
Could someone explain if it has any difference at all? assuming in both cases the surrounding of the fans are sealed.

 

[anorlunda]

Your question is unclear on several levels.

What do you mean by a perforated wall?

CFM though the fan or through the wall?

why do so many people install their fans directly on top of it?

What most people? What are you talking about?

 

[nomisme]

Your question is unclear on several levels.

What do you mean by a perforated wall?

CFM though the fan or through the wall?What most people? What are you talking about?

Sorry about the confusions.
CFM would be thru the fan and perforated wall means a wall with holes.
I could see many desktop fans mount their fans directly on the wall. But by my simulation, it shows if i put some distance between the fan and the wall, the CFM thru the fans is increased. So I just wonder if it has this advantage, why don’t we see this design in those fan mounting of those desktop computers.

 

[anorlunda]

My guess is that the purpose of the fan is to get the warm air to exit the confined space and be replaced with cool air coming in elsewhere. Circulating air inside a confined space does not cool, it heats.