Hi,

I think for "turbulent viscosity limited to viscosity ratio of 1.000000e+05 in 18252 cells", mostly, it is caused by meshing quality. It can be skewness, aspect ration or orthogonal quality. My advice is fix the meshing.

The "reversed flow in 274 faces on pressure-outlet 18" error message indicates that there is a problem with the boundary conditions at pressure outlet 18. This error can occur if the pressure outlet boundary condition is not properly defined, or if the flow direction at the outlet is opposite to the expected flow direction.

The "Divergence detected in AMG solver: k temperature limited to 1.000000e+00 in 8519 cells on zone 2 in domain 3" and "turbulent viscosity limited to viscosity ratio of 1.000000e+05 in 18252 cells" messages indicate that the solver is encountering numerical instability during the simulation. This can be caused by a variety of factors, including an inappropriate grid, inaccurate boundary conditions, or a poorly defined model.

The "floating point exception" error message indicates that there is a problem with the numerical computation being performed by the solver. This can be caused by a division by zero, an invalid operation, or an overflow.

There are a few things you can try:

I hope this helps!

Looks like mesh issue. Check your mesh quality. From my experience working with boiling you need to refine mesh a lot and generate high quality mesh. In your case it diverges right away, if you manage to run it keep in mind that poor mesh quality can produce other weird effects, for example you might not see phase change. I had a small project on heat pipes and it was all about high quality mesh and proper time step.

For good meshing, you can use method->multizone -> hexa -> Pave -> Hexa core and set element size based on the papers you have read. Make sure average skewness and Orthogonality less than 1 and Aspect ratios less than 5.

In Fluent window, check case and check VOF after initialisation, most issues are available in the message.