We have an exciting announcement about badges coming in May 2025. Until then, we will temporarily stop issuing new badges for course completions and certifications. However, all completions will be recorded and fulfilled after May 2025.

Ansys Learning Forum › Forums › Discuss Simulation › Fluids › Doubt on gravity effect at pipe oulet in Fluent › Reply To: Doubt on gravity effect at pipe oulet in Fluent

July 29, 2024 at 12:11 am
Alex Chiella
Subscriber

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?