[ignacio]

Hello,

I would like to ask for advice for the following VOF simulation

I have a liquid pool with a gas space above.
All boundaries are walls except the ceiling, which is a pressure outlet.

Fluent recommends to use the following operating conditions with VOF
Location: Gas space
Ref density: Lightest phase (air)

This leads to a zero pressure in the gas space, which minimizes the round-off errors and improves the convergence of the simulation. All good.

However!
In my case, I am interested to resolve accurately the body forces in the liquid.
Using Fluent recommendations leads to low round-off errors for the gas pressure, but large round-off errors for the buoyancy in the liquid. The results were actually quite bad when using these recommendations. Thus, I switched to the following operating conditions
Location: Pool surface
Ref density: Liquid

Using those conditions the pool behavior is well predicted, but the convergence of the simulation is quite bad due to the high pressures in the gas space.

What it then the best approach to have
1) Accurate body forces in the liquid?, and
2) Good overall convergence?

Any suggestion will be appreciated =)
Ignacio