Reply To: Doubt on gravity effect at pipe oulet in Fluent

[Alex Chiella]

Dear Rob, hi again!
Took some time to try to get the Operating Density straight, thank you a lot for pointing me there!!

I tried running a slightly different geometry, with everything made from scratch including the SpaceClaim CAD (just to make sure I did not screw up axes choices and whatnot). I set the Operating Density to 0.142 kg/m^3, which is the value I got at the pipe outlet on precedent runs. That's pretty much the hydrogen density at normal condition, slightly increased because of some light air dilution. While in this new case I get some slightly different results (which is understandable), the issue at hand is exactly the same.

This is what I get using the Operating Density above both for ideal gas and incompressible ideal gas:

 

The lighter gas gets push downwards, again.

The pathlines are mushroom shaped:


I'm going to rerun the same exact simulation I showed above using non-zero Operating Density too, just in case.

P.S. For some reason now I have Fluent running the hybrid initialisation as soon as I try to Edit... the project (I'm working via Workbench because I'm hoping to perform a parametrical analysis one I get the DP0 down correctly). Have no idea how it happened nor how to stop it, in this way I can't checkout the saved solution because it gets wiped away. What did I do wrong this time?