I have conducted CFD analysis in ANSYS fluent for some airfoils like NACA 2412, NACA 4412 etc. But I have no options to validate my results experimentally through wind tunnel experiments. In the airfoiltools.com website there are required graphs for validating the simulated Cl vs alpha, Cd vs alpha and some other graphical results. However, are those graphs experimentally correct to validate our gotten CFD analysis? My additional question is that I found my simulated result matches with the website's results for Cl vs alpha, but for Cd vs alpha, the variation is more than 10% or 20% or sometimes even more. Why does this happen? If my value of Cl is almost accurate, can I ignore the deflection of Cd value?