[Issues with a mesh-NITF physics-Heat Flux Sensor simulation]

Dear all,

I have an issue while adding an air layer to my model.

Description of the project:

I am trying to simulate a heat flux sensor in order to improve its design. To approach my sensor I need to add some thermal resistive layers accounting for the glue I used during the build up.

Description of the problem:

When I add a second (circular) air layer under the substrate of my sensor (Geometry 1 -> Air Layer Keramic (1/2) and (2/2)), I can still generate the mesh properly.

However, as I run the simulation (study 7-steady state) the following error appears:

Problem setting up multigrid.
Failed to build feature 'Boundary Layers 1' in sequence 'Mesh 1'.
..
- x-coord: -1.76
- y-coord: -1.76
- z-coord: 24.265
- Detail: Could not shif the boundary node at all
...

The error is available in attachment as error.png


Description of the files allowing to reproduce the problem:

1) The error.png is a figure that shows the COMSOL error.
2) The 3D_laminar_8cores_1layer.mph is a COMSOL simulation where the mesh is successfully generated and that runs without problems.
3) The 3D_laminar_8cores_2layers.mph is the same file as 3D_laminar_8cores_1layer.mph despite a second air layer was added (see Description of the problem) to account for the glue between the substrate (keramic) and the housing (kovar).

Expected answer:

I hope someone can reproduce the problem and provide me hints about how to modify my mesh in order to prevent the multigrid error.

Is there anyway to solve the problem without the multigrid approach?

With Kind Regards,

Meier Thierry

PS: I cleared all meshes and solution of my model before uploading them (to reduce their size).