I created a new simulation project called 'Window installation detail':
A thermal assessment of a window installation detail for understanding the thermal bridges present.
More of my public projects can be found here.
I had a look to the results. This could be made better by creating similar mesh element size in the contact faces. This is achieved by performing face splits to match the contact faces and then defining same level of refinements to both faces. Kindly have a look into the following.
Step-by-Step tutorial using Onshape and SimScale
Please let me know if you have any other queries.
The mesh elements corresponding to green face has comparatively larger cell size, to that of blue ones. Defining same level of refinement should avoid ambiguity!