I couldn't find any trace of `MPI-MVAPICH2` in the OpenFOAM build scripts, but there is a "catch all" fallback that is used when the value passed to `$WM_MPLIB` is unknown, in `etc/config/settings.sh`:

```
case "$WM_MPLIB" in
...
*)
    export FOAM_MPI=dummy
    ;;
```

I'm guessing we can get away with this because we're using `mpicc` as compiler, and so finding header files or libraries is not a problem.