Boundary conditions

At the inflow all flow quantities including the velocity components and turbulent properties are prescribed. The level of turbulence at the inflow is set to $Tu=\sqrt{\frac23 \frac{k}{u_0^2}}=0.1\%$ and the turbulent viscosity to $\mu_t/\mu = 0.1$. At the outflow, a convective boundary condition is used that allows unsteady flow structures to be transported outside the domain. For the three-dimensional computations a periodic boundary condition is applied in spanwise direction.

The complete airfoil surface including the Gurney-flap is modeled as a non-slip boundary condition. As the resolution is very fine no wall-functions have been applied but the low-Re formulation of the $k$-$\omega$ model can be solved close to the wall.