Piping efficiency

[dobit]

I will be moving solid materials in a horizontal pipe using pull system(i.e. negative pressure). My options are (1) to have all my three vertical pipes drop into the horizontal pipe and pull the materials or (2) Have two vertical drop into one side of a 'Y' setup while the third vertical drops on the other side of the 'Y' before the convergence of both horizontal pipes.

My question is that which of these two setup is more efficient?

 

[sciguyjim]

Thinking of a somewhat simplified setup, I'm thinking that much of the friction in the moving stream will be caused by friction with the pipe walls. Therefore, the more efficient setup will be one with the least wall surface and most interior volume.

Concerning the mixing of materials from vertical and horizontal pipes, I would angle the pipes to merge gradually rather than just have a 90° junction. This would be similar to the "Y" setup you mentioned.

These are just my guesses.