Turbulent viscosity limited to viscosity ratio of 1e+05

** Turbulent viscosity limited to viscosity ratio of 1e+05

*** reason
The possible *causes* for large turbulent viscosity ratio include:
- Bad initial conditions for the turbulence quantities (k and e)
- Improper turbulent boundary conditions
- Skewed cells

*** solution
If the problem is not caused by *bad mesh*, then *the beginning of the phenomena* can usually be avoided by:
-Turn off solving *turbulence equations* for the first 100-200 iterations
-Turn on turbulence and continue iterations

If the problem occurs *in the middle of the iteration process*, then use the following procedure:
- Stop the iteration
- Turn *off* all equations except the *turbulence equations*
- Increase turbulence under relaxation factors (URFs) (k and e) to 1 and iterate for 20-50 iterations
- *Turn back all equations* and reduce the turbulence URFs to 0.5-0.8 and then continue iterations
- Repeat the above steps for several times

For *faster convergence*, it might be useful to obtain an initial solution with the *standard k-e model*
before switching to a more advanced turbulence model.

Because some turbulent flows are inherently unsteady,
verify if the flow has any unsteady behavior and switch to transient calculation if needed.