NACA 0012 Airfoil with Spalart-Allmaras turbulence model

Hello,

I am new to COMSOL and I thought I would start with a relatively simple model: a NACA 0012 airfoil at 0 angle of attack.

The domain is small and the mesh resolution is relatively coarse to get faster solutions. (Once it works I will try a larger domain and finer mesh)

I chose the Spalart-Allmaras Turbulence model given its robustness and accuracy in these conditions.

Unfortunately, the simulation always exits prematurely with an error:
Segregated group 2
Expression evaluates to NaN.
- Expression: (((mod1.spf.cb1*mod1.spf.Stilde)*mod1.nutilde)-((mod1.spf.fw*mod1.spf.cw1)*((mod1.nutilde/mod1.spf.l_w)^2)))

I have played with different boundary conditions, mesh densities, solvers. Nothing seems to work.

Any help on this would be greatly appreciated!