Pond Flow Simulation

I am trying to model a raceway pond driven by a paddle wheel in Flow Simulation.  The pond is open to atmosphere and I am given the velocity at the paddle wheel location. I have modeled a solid wall across the channel and up to the height of the fluid (water).  I am using an External Flow Analysis and have set the Computational Domain boundary at the height of the fluid and initial conditions at atmospheric temperature and pressure.  Can I use an internal fan with the inlet and outlet faces being either side of the wall to simulate a momentum driver at the paddle wheel (see image below)?  I am looking to see the flow trajectory and velocity around the bends. What are the proper boundary conditions for this situation to simulate pond flow?