Code to code comparison for the simulation of the flow around the NACA 23012 airfoil

This paper presents the simulation of the two-dimensional flow of an incompressible fluid around the NACA 23012 airfoil. The selected angle of attack is 12^o and the Reynolds number based on chord length and incoming velocity is 3x10⁶. Three flow solvers are used to solve the Reynolds-Averaged Navier Stokes equations supplementedwith the k - ω SST two-equation eddy-viscosity model: ReFRESCO, OpenFOAM and Ansys Fluent. Different aspects of the flow simulation are addressed: size of the computational domain; boundary conditions at the outlet boundary; structured versus unstructured grids; grid refinement strategy and discretization of the turbulence quantities transport equations. Numerical uncertainty estimates are performed for the lift and drag coefficients to check the consistency between the three flow solvers and surface pressure and skin friction distributions are compared. The use of first order upwind in the discretization of the convective terms of the k and ω equations has a stronger effect on the solutions (increase of the numerical uncertainty) obtained in the unstructured grids than on the flow fields determined in the structured grids.