VERIFICATION OF CODES AND CALCULATIONS

Background discussion, definitions, and descriptions are given for som e terms related to confidence building in computational fluid dynamics . The two principal distinctions made are between verification vs vali dation and between verification of codes vs verification of individual calculations. Also discussed are numerical errors vs conceptual model ing errors; iterative convergence vs grid convergence (or residual acc uracy vs discretization accuracy); confirmation, calibration, tuning, and certification; error taxonomics; and customer illusions vs custome r care. Emphasis is given to rigorous code verification via systematic grid convergence using the method of manufactured solutions, and a si mple method for uniform reporting of grid convergence studies using th e Grid Convergence Index (GCI). Also discussed are surrogate single-gr id error indicators.