If OpenFOAM was installed on a single user account using the OpenCFD binaries then for another user to have access to it is very simple. All one needs to do is to add an alias of the installation in the new user's .bashrc
If, on the other hand, OpenFOAM (or OpenFOAM-ext) was compiled on a user account (say the user name is MrX) and a new user (MrY) wants to use the same installation, then:
1. MrX must make sure...