Mesh Warning—The shell assigned is incomplete

Issue

Surface parts were defined as part of the material definition. When the simulation was started, the following warning was issued during the meshing process: 

Warning: The shell assigned to surface A is B% complete; remeshing after increasing the local mesh resolution may yield a complete shell 

A is the ID of the surface that could not be shell meshed

B is the percentage of the surface that could be meshed successfully.

Solution

Surface parts are meshed with two dimensional elements, and are typically used to represent very thin objects. Autodesk® Simulation CFD creates them by duplicating the element faces on the surface into virtual wedge elements.  

The elements on the surface are then extruded slightly into the flow to form the Mesh Enhancement layers. This involves moving the surrounding 3D elements slightly to make room for the Enhancement layers. If the element faces on the surface part are too big relative to the surrounding geometric features, it will not be possible to move the 3D elements and preserve the new shell element.  

This warning indicates that some of the shell elements could not be created, and only a portion of the surface part could be meshed. The mesh as a whole will generate, but the surfaces in question will appear to have pieces removed when viewed in Results mode. This usually happens along the corners of surface parts. 

To resolve this issue: 

Refine the mesh distribution on the indicated surface(s). To do this:

1. Open the Mesh quick edit dialog, and change to Surface selection mode (right click and select Selection type > Surface)
2. Select the surfaces.
3. Use the Size adjustment slider to reduce the size of the elements on the selected surfaces.
• Try reducing the slider to 0.7.
• If the warning is issued again, move the slider to 0.5 and try again.