Rob
Ansys Employee

Given R16.2 is 8 years old there have been several changes. If the model isn't in R16 then you can't use it, and as I've nolonger got documentation or the installed software I can't check. 

Model differences are covered in the documentation. However, changes are noted with each release so you've got 20-30 sets of release notes to find and read. I'd skip that and just run on 2023R2.