If STAR-CCM+ fails on large shared memory nodes with the message “mpid: Not enough shared memory”, your sysadmin might need to increase the kernel limits for SHMMAX (maximum size of shared memory segment in bytes), i.e. sysctl -w kernel.shmmax=.... Especially, the Ubuntu/Debian default of 32 MB seems to be too small even for 2-socket nodes with 8-core AMD Opteron processors, i.e. 16 cores/node …