Hello! I've attached an image below that shows a simple diagram of my question. I would like to know how to work out the area that I would need for a funnel to increase the air speed from 4.8m/s to 12m/s. The exit would measure 25 by 25, how big would the entrance need to be? I've done my own calculation and believe that the opening should be 31.45 m x 31.45m. I'd like to see what you all think.