[Pegus]

Good day,

I am trying to model a bubble decompression inside a tank. This tank is half full with water and the other half is air. I have some questions regarding the set up of this problem.
The intention of the bubble has an initial pressure of 50psig and then it drops to 0 psig at 0.1 seconds. I was planning to create this variation with some expressions.
The intention of this analysis is to get the water pressure distribution on the tank walls.

1.- To start with the bottom half with water and the upper part with air, do I need to create 2 domains? or how can I specify this condition.
2.- What would be the best inlet conditions for the bubble? (pressure or velocity)?

Thanks in advance,

P.P

[ghorrocks]

1) Use a CEL expression to define the initial volume fraction. Do not use multiple domains. CEL expressions like step(y) will return 0 for y<0 and 1 for y>0, so this can be used to define an initial condition with a free surface level at y=0.

2) I have no idea unless you explain what you are doing. How big is the bubble? Where is the free surface? What does the initial condition look like? How is the pressure controlled? Please show an image of what you are talking about.