I need help designing what i guess is basically a wind tunnel.. long story here, but i need to make a tunnel that is as tubulence free as possible.. nearly any material, shape, etc you can think of.. but i need to channel a large volume of air asd completely smoothly as possibly through a passage... can be any size really too.. being very vague i know, wish i knew more so i could ask better questions... if anyone can try and direct me in the right direction i would be very grateful

thanks!