I am trying to run a rotation test in flow simulation.  I have taken an assembly and created a part.  I want to sketch the rotational area and extrude it without merging the results, but the option is not available.  any Idea?

Hi Karn,

The main problem I see in this file is that you have only a large number of surface bodies and no solid bodies.  I might expect to see this if you had saved an assembly into a part file using the 'Geometry to save' option set to "Exterior faces".  Surfaces won't work for Flow Simulation so you would first want to rectify that by re-saving the assembly with 'Geometry to save' set to "All components" like you see below:

Once you have a file full of solid bodies then you will find that your extrusion has the 'Merge result' option to turn off.