menter correlation based transition model (Gamma - Retheta)
 

I am working on modeling fluid flow pass over an airfoil and I have some question about Gamma - Retheta transition model:

1- Is 'Y' in 'Rev' formula normal distance from nearest wall or only distance from nearest wall? It means length of normal line to a surface of an airfoil should be measured or only distance from nearest wall should be done?

2- absolute value of strain rate and vorticity formulas in this model was defined as Sij Sij (and same thing for vorticity) .Does it mean we should multiple every same arrays of these tensors for calculation them
(Sij Sij = S11*S11+S12*S12+S13*S13+S21*S21+S22*S22+ ....)?

3- in solving Retheta we have two parameter one is transition onset momentum thickness Reynolds number and second one is local transition onset momentum thickness Reynolds number. Is it solved both of them (first with empirical correlation and second one with PDE equation) in all domain or the first should solved outer boundary layer and second one in boundary layer? and it is necessary to define boundary layer edge or not?

Thanks in advance.