Problem with ExternalFlowAroundObject

I’m trying to simulate an external flow around a object using the example that palabos gives us. I’ve changed the velocity from 0.1 to 0.9 and the kinematic viscosity from 0.001 to 0.0000151 to simulate air. With this configuration after a while the program stop running. Does anybody know what the program stops?
I saw that my computer only workes with 1 CPU at the same time. So I’ve executed the program under the order npirun -np X ./exteternalflowaroundobject externalflowaroundoibject.xml 100. Now I work 4 CPU, and I see it in SystemMonitor, but I don’t apreciate any diference. Dose anybody knows why?

Very thanks,

As far as I know, the velocity in Lattice Boltzmann units should be below 0.3. If it goes above the simulation can explode. Also as you decrease viscosity in lattice units, the simulation becomes unstable. Try to rescale time to make the time step finer. That might help.