Reply To: CFD WITH FLUENT TO SIMULATE THE FLOW OF THE FRESH CONCRETE

[Rob]

You can use any viscous model that describes the concrete, HB may be the best option. 

Divergence may be mesh related, and you need to check the resolution too: cell quality just checks the individual elements. Best way to check is display the mesh on a cut plane and look at it. From there, check model and boundary settings paying careful attention to the time step.