Rob
Ansys Employee

Can you chech the graph axes? The Fluent plot is DPM velocity with postion (not sure if that's horizontal or vertical position) so you may be plotting the wrong thing. The experimental plot may also be for the carrier fluid: typically particles will bounce along the bottom of the pipe and slow the flow, so you get a distorted fully developed flow. 

The other consideration is to take care when comparing 2d with pipeflow. You're modelling the centreline height, and the domain is a "slot" which can lead to some differences.