American Institute of Aeronautics and Astronautics 1 Global Luminescent Oil-film Skin-Friction Meter Generalized to Three-Dimensional Geometry and Applied to FAITH Hill Nicholas Husen 1 School of Aeronautics and Astronautics Purdue University, West Lafayette, IN 47906 Sudesh Woodiga 2 , Tianshu Liu 3 Western Michigan University, Kalamazoo, MI 49008 and John P. Sullivan 4 School of Aeronautics and Astronautics Purdue University, West Lafayette, IN 47906 This paper further develops the global luminescent oil-film skin-friction meter by considering its application to a three dimensional axisymmetric wall-mounted bump subjected to subsonic turbulent boundary layer flow. The geometry gives rise to a necklace vortex and large scale separation on its lee side. An oil-film is only usable by the global luminescent oil-film skin-friction meter if it meets certain criteria. Most notably, it must be sufficiently thick to provide a good signal but not so thick that the relationship between luminescent intensity and oil-film thickness becomes nonlinear. Different regions on the model give rise to a usable oil-film at different times in an experiment. This paper proposes a technique for the selection of which solutions from a sequence of “snapshot solutions” taken during the run should be averaged for a particular region on the model. A relative skin-friction distribution resulting from the techniques proposed herein is presented for each of four sections of the model: One down the model’s centerline, and three across the model in the spanwise direction. Nomenclature y = height of model H = total height of model ℎ = thickness of oil film r = radial distance from origin ሺ ଵ , ଶ , ଷ ሻ = global coordinate system in object space ሺ  ଵ ,  ଶ ,  ଷ ሻ = coordinate system with 1-2 plane locally tangent to surface ሺ  ଵ ,  ଶ ,  ଷ ሻ = coordinate system with 1-2 plane parallel with image plane S = function describing surface of model in ሺ ଵ , ଶ , ଷ ሻ coordinates   = function describing surface of model in ሺ  ଵ ,  ଶ ,  ଷ ሻ coordinates t = time p = static pressure of external flow field ߤ= dynamic viscosity of oil-film  = density of oil-film 1 Graduate Assistant, School of Aeronautics and Astronautics, 701 West Stadium Avenue. Student Member AIAA. 2 Graduate Assistant, Department of Mechanical and Aeronautical Engineering, Parkview Campus, MI 49008. 3 Professor, Department of Mechanical and Aeronautical Engineering, G-220, Parkview Campus, MI 49008, Senior Member AIAA. 4 Professor, School of Aeronautics and Astronautics, 701 West StadiumAvenue. Fellow AIAA.  ௜ = -th component of gravity  ௜ = -th component of skin-friction  ௜௝ = change of coordinate matrix I = Intensity of luminescent oil-film ܫ  = Intensity of the excitation light incident on the oil-film  = coefficient proportional to quantum efficiency of luminescent molecules  = skin-friction   = equivelant skin-friction  = Lagrange multiplier Downloaded by WESTERN MICHIGAN UNIVERSITY on March 15, 2015 | http://arc.aiaa.org | DOI: 10.2514/6.2014-1237 52nd Aerospace Sciences Meeting 13-17 January 2014, National Harbor, Maryland AIAA 2014-1237 Copyright © 2014 by the American Institute of Aeronautics and Astronautics, Inc. All rights reserved. AIAA SciTech