Fluid/fluid interface
 

Let's say you have a tank filled with a liquid at the bottom, and air on the top. Perhaps you want to run some type of mixing simulation, or heat transfer analysis. How would you set up the simulation in FloEFD to account for the fluid/fluid interface of the air and liquid in the tank? Would a fluid subdomain be used? Every example I've seen with this involves heat exchangers where the two fluids are separated by a solid region.

As an experiment, I tried creating a part file that is a cylinder, importing it into the model and disabling it in component control then defining this as a fluid subdomain for the liquid in the tank, but it doesn't seem to work properly. Can FloEFD even handle problems with a fluid/fluid interface? Thanks.

EDIT: I now looked it up and the help topics said a fluid subdomain can only be applied to a "closed" fluid region, so I guess my original question is better phrased as: can FloEFD simulate interaction between two fluids in the same, enclosed region? I know if the fluids are both gases, you can specify the concentration that either exists or is entering the domain, but what if you have a gas and a liquid?

Hi Adam,

Yes, in general FLOEFD can handle such cases. But these are known as Free Surface where you have two different fluid types such as gas and liquid or two non-mixing liquids like oil and water.
There is an option in the general settings to select free surface.

But please have a look at the technical references to see the limitations of this method.

Regards,
Boris