Divergence in multiphase stirred tank reactor simulation
 

I'm working on a multiphase simulation in Ansys fluent (air and water) to characterize a stirred tank reactor.
Multiphase model: Eulerian
Turbulence model: k-epsilon with standard wal functions, dispersive model where secondary phase is considered to be laminar

Cell zone conditions:
I am using a multiple reference frame model which has a stationery domain and a moving domain around the impeller with an angular velocity of 120 RPM.

Boundary conditions:
The tank wall and baffles are modelled as a stationery wall.
The shaft is modelled as a moving wall with an angular velocity of 120 rpm relative to stationery domain.
The impeller is modelled to have an angular velocity of 0 rpm relative to moving domain.
The sparger is modeled as velocity inlet with volume fraction of 1 for air with inlet velocity 0.07m/s. Water velocity is 0.
Top of the reactor modelled as a degassing domain or pressure outlet (with a backflow volume fraction of 0 for air).

With the above model, the simulation keeps diverging. The error message saying the turbulent viscosity ratio limited to 10^5.
When the pressure outlet boundary condition is used for top of the vessel, an error of reversed flow in 1027 faces keep coming up.

I request the members of the community to help out on where I am going wrong.
Happy to provide any more details as required.

Thanks in advance!