Hello I have a vertical pipe with floating ping pong ball in it. I have fan at the bottom that that push the ball up. The pipe parameters: D=45mm L=1.07m Ball parameters: D=40mm M=2.7g I tried to change fan speed to move the ball but becouse turbulance the ball is not steady, and so I can not control ball hight with fan speed. I installed step motor at the top to open and close the hatch, it seems to be working. I have now problem to calculate all of it. If I look at the ball that floats in the air (inside the pipe) , the forces that I believe are effecting the ball are: fg-weight force (down) fd-drag force (up) fb-buoyant force (up) And I believe that there is a some turbulance force that pulls the ball down. I cant use stocks equations becouse Re number is more than 2300 and I cant use bernoulli equations also becouse I have turbulance. Eventually I need somehow to calculate the pressures ratio between two sides of the ball, and develop formula for ball's hight. Please help with this.