Mike Rife
Ansys Employee

Hi @Lovisa Svanborg  The complexity/simplicity of the model is not necessarily an issue.  Mesh a unit cube fine enough and eventually it will need more RAM than is available.  

There are a lot of paths you can take to address this but I am assuming some you don't want to, or can't, take.  For example, how about installing more RAM on the system?  Or solve with multiple compute nodes.  

It would help to know what type of analysis this is and some details of the model.  Is this an assembly of solid parts (not beam and/or shells)?  If so try changing the Mesh default to use linear elements.  This will decrease the node count, and so reduce the memory requirement.  Then once solved you can post-process and determine where a finer mesh is needed to provide an accurate capturing of the strain/stress field (assuming some kind of structural analysis here).  Then go from there.