How to increase flow rate? I am coming up with ideas of how to increase grain (corn, soybeans etc,) flow in a tube.  My first idea is to have spiral ribs inside of the tube to create a vortex effect that will allow the grain to flow at a greater rate, any ideas to if this would work or not?
 A: I don't think creating a vortex effect will increase the velocity of flow, because it would direct movement in a direction other than forward.  Smooth bore gunbarrels, for example, have greater muzzle velocity than rifled gunbarrels (assuming all other variables are equal).
You might want to maximize laminar flow and to minimize turbulence inside the tube.  Teflon coating, and ensuring that the grain nearly fills the cross section at all points in the tube, without jamming, might help.
Providing pinpoint air vents which increase in number toward the tube's outlet, might help speed the grain on its way by decreasing pressure, but I'm not sure this would help prevent jamming.
Here is a link to some pipe flow software (maybe it could apply not only to liquids, but to grain):
http://www.pipeflow.com/
Also:  http://en.wikipedia.org/wiki/Pipe_flow
A: The key to flow of macroscopic particles is to make sure they don't "clump" or jam. I don't know what is propelling them down your pipe (gravity? Air flow?) but that will affect the answer. In general, adding some vibration keeps particles flowing freely; a larger pipe diameter with minimal obstructions / bends is the other thing. Making the pipe diameter slowly increasing will also improve your chances to maintain flow.
