I have been able to converge a 1 velocity group MUSIG model but I am still having trouble with the 2 velocity group case. When configuring an iMUSIG model does CFX automatically set up the mass source and sink terms connecting the 2 polydispersed phases?.I ask because I specify all the air entering my domain in velocity group 1, The largest bubble size of velocity group 1 has size fraction of 80%, yet the volume fraction of size group 2 is tiny (6E-6) . n