Hello. Im bilding a device. I have 1m vertical pipe with fan in the bottom and stepper motor at the top with sliding ping pong ball in it. (pipe d=45mm, ball d=40mm 2.7g) Stepper controls ping pong high in the pipe. The device is working but mehanics is not my aria at all so it is very difficult to me to calculate all of it. I have 25 CFM fan that located a couple mm under the pipe that working at a constant rate, my question is how I can calculate using Bernoulli or Stocks laws if some of the airflow is getting out from the space between the fan and the tube. Also how can I calculate the pressures ratio if I have turbulence on the sides of the ball. Please help.