Centrifugal pump question.
When a centrifugal pump is running, how much energy is required to fight against the coriolis force of the spinning water mass that flows from center toward the circumference?
I have done some simple experiments with a tube. The tube have a water inlet in the middle of its length, so the open ends of the long tube is following the circumference. When it pumps water, even only 1cm above the water surface, it requires lots of energy to sustain rotation - even if the water is lifted only 1cm. This energy requirement is due to the coriolis counter force. However, If I put on a 90 degree bend, on each ends of the tube, that points away from rotation, it seems the pump runs much lighter with less energy input, and also pumps much more water at same RPM. How can this be possible (Well, it IS, but why?)?