Hello all. I searched "interior face" and read many discussions, but didn't find a solution to my issue:

I'm using Fluent (2ddp, axisymmetric) to model two fluid zones. Zone 1 is a field of liquid 1. Zone 2 is a smaller sphere of liquid 2, surrounded by liquid 1. I defined the face where these two zones/meshes meet as "interior". My hope was that when I applied axial velocity to fluid 1, it would "bump into" the face of zone 2 and move around that zone. But instead fluid 1 passes straight through that interior face. I confirmed by analyzing both velocity vectors and path lines.

How can I keep one fluid from crossing an interior face into another fluid? Thanks for any assistance. These forums are very helpful...

if you define it as interior the fluid will mix with the one on the other side. if you want ot prevent it from doing so define it as wall. i think you have not clearly stated the problem

If I declare the boundary a "wall", then I presume it will not allow species transport across that wall(?). The goal of my model is species transport from one fluid to the other.

understood now.

i am not sure what is the solution to this problem.

I think you can define species at the wall using boundary conditions if the species model is ON

I think I understand. Basically, declare the spheres as walls with a fixed mass fraction. Then the surrounding fluid would "pick up" mass fraction from these spherical walls since I allow Species Transport.

I just tried it, but the steady analysis would not iterate. It gave me an error "Error: Floating point error: invalid number". And another error "Error Object: ()". Not sure what any of that means.

Never mind my last note about error messages. I rebuild the model in Gambit and now it works splendidly. Thanks again for the advice. Sometimes it's the simple things that take the longest to realize...