Interior surface body in 2D
 

Hi,

sorry for a dummy question, but I have some difficulties to understand how Fluent creates boundary conditions.

I have a simplified case where I want to study heat transfer. The geometry consists of 3 rectangle surfaces. One rectangle represents solid 1 and two rectangles represent solid 2. The edges around the rectangles will be set as walls with various temperatures or heat fluxes.

Now, here is the problem. I created the mesh and created named selections for certain bodies (solid 1 and 2) and edges (walls and axisymmetric boundary condition). When I import the mesh and geometry into Fluent, it automatically creates surface bodies between all the rectangles. It is not clear to me why it creates surface body (boundary condition-interior) between bodies that form one named selection, i.e. one cell-zone condition (solid 2). The mesh is conformal. Is that okay? Fluent does not do that while I am working in 3D. In this case, it is not a problem, but with a more complex 2D case it gets confusing.

Thanks in advance.

It happens and it can happen for 2D and 3D. It's a fault of the mesh generator in assigning properties which Fluent misinterprets when the mesh is read. It's purely aesthetic and doesn't affect the solution.

You can leave it as is or a quick fix is to simply merge these surfaces (which are of type interior) with interior parts that look like they are in the volume (I think interior-solid2 for your case).

Thanks a lot! I was afraid that I forgot to set some properties or dealt with a 2D case in a wrong way.