Rhino closed solid polysurface becomes sheet body in Simscale

Please can you help.

I have a closed solid polysurface in Rhino but however I import it to Simscale it fails due to there being sheet surfaces. How do I solve this in Simscale, there is talk in the documents about joining them in Simscale but I cannot find out where. Has anyone else had this problem.

Thank you

Will

Hi,

When opening your geometry in Rhino and using the What command on the main part of the assembly, it is reported as an open polysurface, and not a closed one.

When using e.g. ShowEdges > Naked edges, it highlights edges around here.