fluid subdomains are completely enclosed
you could try applying initial conditions to your fluid body
but i think in the long run, this isn't going to be a good analysis for solidworks flow simulation. take a look at the suggested articles on the right and also the solidworks KB for filling/emptying analysis in flow.
what exactly do you want to learn from the analysis?
I finally got it to work after playing around a little bit more. Just need to get the right sequence: Set analysis to internal, create fluid body assembly, insert fluid body assembly into volume it was created from, set analysis back to external, disable fluid body assembly in component control, rebuild project, then set initial conditions of fluid body assembly. The step that I was missing before was rebuild project, Solidworks would not accept the component for initial condition settings until I did a rebuild.
I am trying to reproduce a muzzle blast using data from interior barrel pressure and temperature measurements. I have tried using different inlet time dependent sources of pressure and mass flow inside a small length of barrel to get the flow to choke at the exit. When I ran the simulation trying the two different types of inlet sources the flow either stays supersonic in the barrel or the mass flow rates exiting the barrel didn’t work out. So far setting the barrels volume to the initial conditions of pressure and temperature at the start and letting it “blow out” is giving the best results.
I still have a problem where the mass flow rate of the gas exiting the barrel starts climbing gradually when the pressure is still decreasing at around half initial pressure which doesn't seem right. I suspect that the gas temperature profile I am using is off a bit.