Yes. FluidFlow allows you to model the effect of changing the pump operating speed or impeller diameter from the Input tab of the Data Palette providing you have entered a Min and Max speed and Min and Max impeller diameter range for the pump in the database.
If you model changes in pump operating speed or impeller diameter, the software automatically applies the affinity laws in the solution and will determine the effect on duty pressure rise, efficiency, power requirement and NPSHr.