Hexa-Tetra merge with partially very fine grids
 

Hi, I've been working on merging hexa-tetra grids.

Although I've been successful with relatively uniform and coarse mesh,
I'm having trouble with partially very refined mesh as you can see from the picture.

In order to have y+ equal to 1, I need very refined mesh even on the interface where hexa and tetra meet.

At first, I tried to merge tetra with existing hexa grid,
but ICEM keeps printing error message in the picture I uploaded(second one).

Secondly, I've tried with Octree scheme with 'Use exisiting mesh part' option to use hexa interface mesh, but since the geometry is not clean, for very small size tetra, gap between lines and sufaces become leakage, thus I can't have tetra without gap problems.(Fix function doesn't work for some gaps, and since the geometry is complex, I'm not sure if I can fix this geometry)
And sometimes I see the similar message like in the first method.


Does anyone know how to merge hexa-tetra mesh when hexa is partially a lot refined? I don't even know what size tetra should be given in the first place.

The smallest size of grid on the interface hexa grid is about 0.001 mm and the largest on the interface is about 3 mm.

Any suggestion would be appreciated.
Thank you for reading this.