[Skulemate]

Yeah... I am familiar with Bernoulli's one dimensional flow equation. Suppose you write the equation for a point just before the pump and another just after the pump. Assuming that the elevation head is very close to the same on both sides, what you end up with is an increase in the pressure head, since the velocity head is also going to be approximately constant. So, I guess then that I was right... that the pump does indeed add potential energy to the fluid, which immediately becomes kinetic energy. As for not mattering... well, that may be true, but I was still curious.

P.S. Useful work would not be that hard to calculate, assuming that you have a good pump curve. If that were the case, you only need to know flow rate to determine the useful work, since the head produced by the pump can be read from the graph.