The problem I’ve encountered is that there’ve been some parts on my geometry model where the mesh elements were missed after generating the mesh when I used facet selection to select some specific facets with two .stlfiles at the same position, so how to fill the missed mesh elements that I thought were caused by the facet selection of another model (another .stlfile)
It is hard to tell from the figure. Is your geometry water tight after you split it into several STL files? You can also check the output message to see if any stl triangles were ignored during meshing due to long aspect ratio.