Look at the manual.  There should be a -t argument for generating

multiple tasks withing a single computer (threading), 

Fluent also has built in MPI support.  You need to use the -cnf argument to

specify a file containing a list of machines to launch on. 

In Torque or PBS schedulers this would be  -cnf=${PBS_NODEFILE}

You can also change to OpenFoam, which is opensource, in case you run into

licensing problems with running multiple copies of Fluent.

See below:

www.engr.uconn.edu/~barbertj/CFD%20Training/Fluent%2012/tut26.pdf

thanks a lot

To me looks like you were asking how do I submit 5 cases with say different inlet velocity. You can use the (Text User Interface) TUI commands in FLUENT to create a txt file that with which you can change the BC's and also submit the case for run.

exactly, that what I mean

If you don't have the Fluent licence, don't use more then 4 parallel processing.

I have the Fluent licence.

thanks a lot