cfd pump.
 

Hi, I am modelling a Centrifugal single blade watewater pump. I am modelling my flow by specifiying the pressure head accross the pump and the rotation velocity. I get a decrease in flow rate as I increase the Head. This is as would be expected. However, from experimental results, I expect the power required at the blade to decrease as the head increases. My CFD results do not show this, they show an increase in power as the head increases. I am using a 2D model.Segregated solver, PISO scheme. I am modelling unsteady turbulent flow and my time step is 6 degress rotation. Has anyone any suggestions as to why this is happening??