Is there a way to set the inital conditions of a volume or "Fluid Subdomain" and run it in an external analysis?

An simple example that I tried is to set a air tank to an initial pressure and let it vent to atmosphere through a nozzle while showing the exhaust plume using external analysis.  I can set the tank pressure with internal analysis using insert fluid subdomain with a lid at the nozzle, but if change it to external analysis and disable the lid in component control it redefines the whole computational domain as the fluid subdomain.

I tried inserting a fluid body assembly created in check geometry into the tank volume but I can't get it to accept it as a fluid subdomain, I keep getting "Cannot find the faces associated with this item" error.

I have been looking around for examples but haven't found any.

Thanks.