Fluid Dynamics trick

thingiverse

These pieces enable you to demonstrate aerodynamic suction using blowing air effectively. The top disk is designed to fit snugly into a standard adapter for an air mattress pump, depending on your specific tolerances. Once the pump is turned on with air flowing, slowly move the lower disk toward the upper disk. You will feel the force of the air jet pushing the disk away until you get close to the other, at which point, the air will suddenly suck the two disks together. The air continues blowing and a small gap of about 1 mm remains between the two plates. With some complex math, you can calculate the expected gap width or the maximum force of the aerodynamic suction. I have two sets of disks available - large and small - both of which work well. The cones on the centers of the lower disks serve to direct the air jet and prevent it from sliding. To set up this demonstration, you will need an air pump and an air mattress adapter (or print a custom adapter).