For that description, I have created a demo model (Centerline1start.sdy) you can use.

Import a CAD geometry that include the cooling channel(s) as a solid
(Change Analysis Sequence to Cool(FEM) or Cool); not needed to create a centerline but needed if you want to run the cool analysis, in this example Cool(FEM) is used
Select Tab Mesh
Selection tab and change to CAD Body
Click on the Cooling channel solid and right mouse button (RMB)
Select Change Property Type…
Click on Channel (3D)
Select Tab Geometry
Select the arrow at Curves and choose the new feature Center Line
Hit Apply (You will receive the centerlines + the properties are set + the diameter of the channel solids will be assigned to the lines)
Mesh the lines
Set Coolant Boundary to one end of the coolant channel: Inlet-> RMB Coolant Inlets/Outlets select Set Coolant Inlets… (In this example, no Outlet is needed)
Start the analysis (Mold elements are available in Layer CAD Mold Geometry Tetras)

Also, the complete model is attached (Centerline1finished.sdy)

Attachments