KR108: How to resolve warning message saying the turbulent viscosity limited to viscosity ratio?
Also review Siebel Solution 2002233.
The message you are seeing is more a warning than an error. It stipulates that the ratio of turbulent viscosity over the laminar viscosity is large than 1e5.
While this is not an error per-say, it is usually unphysical to have such a high ratio (note that this ratio limit is defined in Solve-> Controls -> Limits).
This ratio becomes very high in region of high turbulence, where the grid is (in most cases) too coarse.
In many case, this message occurs at the beginning of a simulation and will disappear as the simulation converges.
If it doesn`t then the first step would be to refine the grid in the regions where this limit is reached (this ratio can be plotted using Display -> Contours).
You can either re-create (and refine) the grid in its entirety or you can adapt the grid "on the fly" using a grid adaptation based on the value of this ratio.