When I did my simulations under a server with 4 AMD Opetran CPU, I tried the "star hostname, 4" but echoed the right-handed error (including the moving mesh in case). How should I set-up the star command to run the parallel computations? By the way, the Lagrangian multi-phase flow was also inclued in my case.

Thanks a lot!

U have moving mesh. So be cautios while using HPC. You have to use manual option while giving HPC run for moving grid problems. All the moving mesh cells should be on one cpu. Read the appendix H in star userguide to use manual option. Default option is metis.