Two phase model?
 

I need to observe the high viscosity fluid goes through the complex model in the initial condition that the air in the complex model.

I use unsteady mixture models.
The high viscosity fluid is set as primary phase and air is set as secondary phase, then I patch the fluid of model as air.
Inlet set 0 kg/s in the air and 0.0006 kg/s in the high viscosity fluid.
But the residual is divergent.

Do I use the right method?

Can someone give me some suggestions?

Sincerely~