Sinusoidal Venturi for Flow Measurement

This is a venturi tube with a sinusoidal profile. Venturi tubes like this have several uses including measurement of volumetric flow rate of fluids. If you know the diameter of the big hole, the smaller hole, and you measure the pressure difference between the upstream flow and the "tap" hole, you can calculate flow rate.

NOTE: this is just my idea for a venturi tube - I'm not sure this profile is a good idea. I'm trying to design a low-resistance venturi - one that doesn't cause a lot of turbulence. For a traditional profile see https://www.thingiverse.com/thing:3559666

This part is designed to be inserted into a round pipe or duct.

P.S. Customizer uses an older version of openscad. I had to work around a problem - see the code if you care.

Why do this? Wala: https://youtu.be/rEZb9C-fU_8