The Navier-Stokes have no problem with stall. The problem is that the Navier-Stokes equations are hard to solve (to use them predictively). The Euler equations do not account for turbulence at all. The Euler equations are good at modeling pressure, which is good for lift and shocks, but does not predict drag, and does a bad job when stall occurs. The RANS equations (a simplified form of the Navier-Stokes equations), do account for tubulence, but one needs a good turbulence model. No turbulence model handles stall well on a broad spectrum of cases, but the RANS equations do do pretty well for attached boundary layers (loosely, when shapes are "aerodynamic" -- like an airplane rather than like a truck or sphere).
Comments
The Navier-Stokes have no problem with stall. The problem is that the Navier-Stokes equations are hard to solve (to use them predictively). The Euler equations do not account for turbulence at all. The Euler equations are good at modeling pressure, which is good for lift and shocks, but does not predict drag, and does a bad job when stall occurs. The RANS equations (a simplified form of the Navier-Stokes equations), do account for tubulence, but one needs a good turbulence model. No turbulence model handles stall well on a broad spectrum of cases, but the RANS equations do do pretty well for attached boundary layers (loosely, when shapes are "aerodynamic" -- like an airplane rather than like a truck or sphere).