I am having a little trouble understanding exactly what you are simulating, sometimes pictures are worth more than 1000 words 🙂 But based upon my understanding, here are some thoughts. You seem to have a pipe with holes in it (like the elementary school instrument the recorder). Water fills a box so slowly water filles these holes and then moves down the pipe towards an outlet. The resistance coefficient for each one of the holes will be the same, but the resistance down the pipe from each of the holes will be different. Think of the hole furthest from the outlet, in the pipe there is only the water from the one hole going through it. But at the hole nearest the outlet, you will have the contribution from the other 29 holes.

You mention multiple simulations. Are these at different depths where there is a different hydrostatic pressure driving the fluid into the pipe? What quantities are you trying to obtain from simulations?

And go Tigers! (Unfortunately it is not their year, again)