I obviously don’t know much about this nozzle, I’m not trying to teach anyone, I’m just having fun brainstorming and hopefully learning something new

Exactly what I’m doing! Haha.

My problem with the “water into a larger diameter pipe” idea is that, while the filament is melted, it isn’t a free flowing liquid that expands quickly to fill it’s container; I’m trying to picture the balancing act that would be required to get the filament to expand by pushing against the build plate/ previous nozzle, but I can only see it ending in a nasty clog.

You’re probably right and it’s likely much more simple than I’m making it out to be. I still like my idea of a baffled nozzle, though. Haha