Advances in manufacturing technology can produce smooth aircraft surfaces to achieve laminar flow at high Reynolds numbers which can reduce drag significantly. Potential benefits include increased range, improved fuel economy, and even reduced aircraft weight, resulting in improved operating economics and reduced emissions. However, due to practical constraints associated with the fabrication and assembly as well as operating constraints, laminar flow conditions are generally difficult to achieve and maintain. Steps or irregularities of the surfaces caused by manufacturing processes, non-seamless paint layers, dust, insects, dirt and even vibration can be enough to initiate transition and cause a laminar boundary layer to become turbulent at elevated Reynolds numbers. The present research effort is focused on using Computational Fluid Dynamics (CFD) to investigate the surface smoothness requirements for a laminar flow nacelle and validating the existing simulation tools [1].