Hi there. I'm doing a 5th year MEng CFD project and would greatly appreciate anyones help on this.

I've set up geometry for the project (a model town) and want to mesh different volumes independently, with one inside the other, inside the other, i.e. a fine mesh for the town, then progressively larger moving outwards.

My main problem is trying to get flow between these volumes. I have done a simply situation with a block inside a block, inside a block, connected the faces, and didn't define any conditions for the internal faces and it flowed through fine, but when I did what I thought was exactly the same thing in the real model, it treated the internal volumes as fluid volumes, but the faces appeared as walls. I find this strange because in Fluent, the faces are not in the list of boundary conditions, because they are not defined in Gambit.

Does anyone have any experience of this issue?

Hello Tom, first have a look if a boundary in Fluent occurs which is simply called something like 'wall' or 'wall:001'. Normally Fluent puts walls which are not defined in such boundaries. When you find this boundary you can define it as interior and your problem is solved. If this is not possible you did a mistake in your pre processing. I assume that you used Gambit for pre proccesing. Most responsible for this are not well connected faces between the different fluids. Or you did only connected the edges or vertices and not the faces.