I am new to CFD simulations. I have done a flow simulation on nozzle with a solid body and also with a shell. I did not get the correct results with shell nozzle (the mesh was messed up)
should we use only solid bodies for CFD even if it is a hollow body?
You need, for internal CFD simulation, just a volume of 'fluid’to simulate, not the enclosure of that volume.
In you current project "nozzle-shell’, only three faces are necessary (in red now). So you will not mesh a shell, but mesh a volume of fluid to simulate.