and the turbulent viscosity ratio should be in the range 
. These values mean that there is some additional viscosity over and above the laminar viscosity, and the dissipation scales are not unreasonable.
When initializing turbulent flows, three turbulence specification methods are typically presented (depending on the turbulence model):
To avoid divergence during the initial iterations, it helps to have reasonable initial values. Admittedly, it might be hard to find a single number that describes the turbulence adequately. However, a good rule of thumb is that the turbulence intensity should be in the range and the turbulent viscosity ratio should be in the range . These values mean that there is some additional viscosity over and above the laminar viscosity, and the dissipation scales are not unreasonable.
Problems can occur when one the flow is initialized using turbulence intensity and a zero initial velocity. In this situation, STAR-CCM+ assumes that the initial velocity is 1 m/s when computing the turbulence values from the turbulence intensity. This might not be a good assumption, so it is preferable to directly specify the turbulence variables when using a small or zero initial velocity. You can still use the standard formulae for estimating the values of the turbulence variables, but use the expected velocities in the formulae, rather than the initial values.