It looks as though it's struggling to create a mesh for the singularity that you have at the end of the cone. Once I cut this off meshing completed successfully. (see image below)
Without the feature history its difficult to see how this was produced, but a revolve with a small radius at the tip should work for you without affecting the results of the sim.
for flow analysis, the fluid volume needs to be generated (i.e) the area inside or outside in which the flow is required.. this generated volume is fluid volume.
for creating the fluid volume remove the unwanted parts in the assembly, to make it simple and solve fast.