port velocity
 

how do you go about to figure out port velocity?

you need a speaker design too... such as winisd...it will give you port velocity and allow you to design port area to keep port velocity in check

A cool little tool that may be useful is an anemometer. Can be had pretty cheap online and measures wind speed/pressure
:).. You might need to learn the math, but the tool is cheap.

use a box design program like bassbox pro you can get it of a torrent if your in to the whole downloading from the internet thing