I started sim racing and it occurred to me rather quickly that these things can get a little toasty in long races.  I started looking for a nice way to mount and fan and found my way into reading about wind simulators.  Now that I have it installed I can say this is a must have when you consider the cost compared to most things sim racing.  I have a P1X rig and my space under my monitors is limited in height, and my searches only yielded the units with the corrugated tube, and most of what I'm reading causes very low performance.  after some research and prototyping this is my solution.  The fans I chose are loud but they blow like leaf blowers, therefore I am very satisfied running them at 55% speed max.

First here are the parts I used:

120x38 Fans, 4 wire PWM  2 of these in my setup

12V 5A Power supply (this one for US) power supply needs to be a little more than max power draw of your fans

Arduino Uno official or this clone works fine for me

LM2596 Buck Converter The ardiuno runs cooler if you can get the power down to 5V to supply it

Wago Lever Nuts  221-412 x6, and 221-415 x2.  No soldering if you go this route

You also need some misc hardware. 

4x 6-32 1" long for control box lid

4x M8 hex nuts for the ducts

4x M8x16 screws of your choice for the pivot points

Whatever hardware you choose to attach it to your rig

Sim hub is the software required to run this and there are plenty of resources online on how to set it up.  Most guides tell you a motor shield is required, but with this type of PWM fan it's not.