In this study, already developed two separate solvers, one for the velocity field and one for the temperature field are run concurrently on two different machines. Each machine here also has multiprocessors which solve each equation in parallel using the domain decomposition technique. The parallel processing is performed via PVM on SGI Origin 2000 and Origin 3000 connected through 10 Mbit Ethernet. Since the machines are not dedicated the communication times may vary for different runs. The runs are first performed for a single domain on each machine handling the mass and the heat flow separately. Afterwards, two overlapping domains are used on each machine. Overall elapsed computational times indicate satisfactory speed up.