After clicking the Automatic Size button (on the Mesh Sizes dialog), the following warning is issued:
Warning: Check model surface diagnostics. Meshing failure may result with default autosize settings
During automatic sizing, several tests are performed on the geometry to find potential problems and obstacles to successful mesh generation. This particular warning is issued because these tests identified one or more surfaces that are slivers. Sliver surfaces are extremely high-aspect ratio surfaces whose edges are very close over their length. They are seldom intentionally created in the geometry, and will often lead to meshing difficulties.
Problematic surfaces have been the reason for many meshing failures or solution problems due to a badly distorted mesh. Identifying and locating them before attempting to run the analysis is essential to reducing wasted time and effort.
To resolve this issue, click the Diagnostics button on the Mesh Sizes dialog, and click the Surface tab to locate such surfaces. If they are colored olive, the mesher will attempt to refine the mesh on them. The drawback is that the resulting mesh may be much finer than strictly necessary for the analysis.
The locations of surfaces identified with Geometry Diagnostics can be saved to a text file. (Click the Save to a text file button.) Fixing these surfaces in the CAD tool is usually the best solution, and this list can serve as a convenient reference.
Products: Simulation CFD