States computational fluid dynamics (CFD) is an emerging methodology where a mathematical model of fluid flow is converted into a digital computational procedure, yielding numbers that approximate the solution of this modelled system, hence the genuine flow state. Points out that a CFD model constitutes the culmination of a large number of assumptions and approximations, and the answers produced are essentially never correct. Examines how good CFD can be in application to room air motion prediction. Discusses the conducting of CFD experiments, both quantitative and qualitative, with examples. Discusses what is required to move CFD into the design arena. Stresses that ASHRAE professionals seeking to use CFD must gain a firm understanding of its limitations and pitfalls, so that confidence can be assured that the numerous error mechanisms intrinsic to CFD are not compromising the predicted results. Validation of CFD predictions must come from a range of quality CFD experiments on the design options for a configuration.