Range of the y+ for realizable k-e wit 2 layer y+ wall treatment
 

Dear Friends,
I am simulating flow of water through a circular orifice to identify any cavitation taking place. When I went through literature the condition of the cavitation to occur is cavitation number<1.45. Cavitation no = f {upstream pressure, downstream pressure, vapor pressure}.
Currently I am simulating non-cavitation zone.
1) Please tell me the turbulence model to be used and its y+ requirement. I tried using k-e model with low, high and all y+ treatment but getting different results for the same.
2) When used realizable k-e model with 2 layer y+ treatment I am getting the results close to the experimental values but I have doubt on the wall y+ values. please tell me the suitable range of the y+ for the application of this model
Thanks in advancce