[Kudzey]

Hello everyone,
I'm completely new to CFD and this is not going to be my main field. However I need to solve a side problem and I was advised to try openfoam.

I need to set up a following case:

1. geometry simmilar to wine bottle ()
2. it is empty at start (vaccum)
3. I fill it up (using the small inlet, all other walls are closed) with liquid 1
(H2 hydrogen in room temp)
4. after a given time I stop
5. I wait another period of time
6. I start filling it with liquid 2 (mollecular Helium, room temp)
7. I stop again after given time
8. I wait for the diffusin to mix thee gases in the narrow part of the bottle close to the inlet

I need to calculate how long I need to wait untill the gases are mixed well enough.

I've created a geometry in 2D (is it a good approximation? there is cylidrical symmetry anyway. Or should I change it to 3D anyway?)

I still don't know:
-how to mark different gases (I've done some tutorilas but it was all about 1 liquid)
-which case or model to use (I don't even know how to model filling it with 1 gas in point 3)

I would be grateful if You give me some advices

thanks in advace
Kudzey