Numerical evaluation of the NACA 0012 airfoil drag coefficient employing a polyhedral mesh

Abstract

Paper presented at the 7th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Turkey, 19-21 July, 2010.

The prediction of the aerodynantic drag coefficient of airfoils is essential in the design of wings and blades of wind turbines. The evaluation of the drag coefficient of a NACA 0012 airfoil at zero degrees angle of attack relies on the Finite Volumes Method adopted by the commercial software Star­-CD, being the RANS equations solved at selected Reynolds numbers. The discrete domain consists of polyhedral cells, which minimizes the number of faces per unit volume as compared to hexahedral and tetrahedral meshes. The present work investigates the steady state regime for selected Reynolds numbers, comparing the results to the experimental ones available in literature. The airflow is incompressible over the airfoil's adiabatic walls where the non-slip condition is enforced. The molecular viscosity is constant and the turbulence model adopted is the k-<>mega/SST/Low Reynolds with hybrid wall function. The calculation of the flow field runs the SIMPLE algorithm. The differencing schemes are LUD for momenta, UD for kinetic turbulent. Constructive aspects of the polyhedral mesh that influences the computational effort, the choice of the turbulence model and the number of wall cells required to achieve acceptable values for y+ and cd are presented and discussed.