[bug_or_feature]

Hi everyone,

Having read quite a few threads I decided to join the forum myself. Thanks for all the help you have already provided me with while not even being registered.

Now to a problem I was not able to solve yet: I am trying to mesh a multi region case (one region solid, one region fluid). I have .stl files for each region (solid.stl, fluid.stl). According to the surfaceCheck utility both .stl files are closed surfaces (which was hard enough to begin with). Additionally both .stl files contain various different patches:

solid solid_region_1
    ...
endsolid
solid solid_region_2
    ...
endsolid

I configured my blockMesh so that the box is slightly larger than my geometry. The geometry is cut in half in the middle because I assume it to be symmetric to that plane (this is the only place where the blockMesh cuts the geometry).

In my snappyHexMeshDict I loaded the .stl files in the geometry sub-directory like this:

geometry
{
    solid.stl
    name solid
    regions
    {
         solid_region_1
         {
              name solid_region_1
         }
         ...
    }
    fluid.stl
    ....
}

I also declared them in the refinementSurfaces sub-dict:

refinementSurfaces
{
    solid
    {
        level (1 1);
        faceZone solid;
        cellZone solid;
        cellZoneInside inside;
        regions
        {
            solid_region_1
            {
                level (2 2);
                patchInfo
                {
                    type wall;
                }
           }
           ...

My Problem is, that all these patches I declared in the .stl file (and it was a pain to declare them and keep the surface closed), are simply disappearing after running snappyHexMesh. It just puts "defaultFaces" and "solid_to_fluid" in constant/soild/polyMesh/boundary. It also keeps adding "domain0" (and respective boundaries), which is the empty space resulting from the blockMesh being a little bit bigger than the actual geometry.

My question is: How can I tell snappyHexMesh to keep all the patches that are nicely defined in the .stl files so I can use those patches to apply boundary conditions in my simulation later on?

I found quite a few threads on similar topics but non provided the answer I was looking for. I even ran snappy only on the solid part of the geometry (altering all the necessary files of course) but that does not change the problem that my patches are gone after the meshing process.

Can someone give me a hint what I am doing wrong?

Best regards and thanks in advance