How would the quadratic elements to be used?
 

There is an option, Quadratic Elements, under the Shell Meshing Parameters, which is default to be checked off. How would this option be used? And it seems there is no such an option for the volume meshing.

Many FEA solvers use quadratic elements for a better fit to the geometry. It places an extra node on the middle of each side of each element and projects these to the surface... The edge is then formed as a quadratic curve between the three nodes...

All CFD solvers (that I know of) use linear elements.

how can I export a 27-node elment information?
 

I need to obtain a mesh information with hex27 for a further calculation, while I can only export the mesh information with only 20 nodes in each element in nastran format with ICEM CFD. The structure has been meshed by hex27 already. So is there a way to do this?

Thanks a lot for advices !