Aturbulentseparation-rcattachmentflowinatwo-dimensionalasymmetricalcurved-walldiffuserisstudiedbyatwo-dimensionallaserdopplervelocimeter.Theturbulentboundarylayerseparatesonthelowercurvedwallunderstrongpressuregradientandthenreattachesonaparallelchannel.Attheinletofthediffuser,Reynoldsnumberbasedonthediffuserheightis1.2×10~5andthevelocityis25.2m/s.There-sultsofexperimentsarepresentedandanalyzedinnewdefinedstreamline-alignedcoordinates.TheexperimentshowsthatafterTransitoryDetachmentReynoldsshearstressisnegativeinthenear-wallbackflowregion.TheircharacteristicsareapproximatelythesameasinsimpleturbulentshearlayersnearthemaximumReynoldsshearstress.AscaleisformedusingthemaximumReynoldsshearstresses.ItisfoundthataReynoldsshearstresssimilarityexistsfromseparationtoreattachmentandtheSchofield-Perryvelocitylawex-istsintheforwardshearflow.Bothprofilesareusedintheexperimentalworkthatleadstothedesignofaneweddy-viscositymodel.ThelengthscaleistakenfromthatdevelopedbySchofieldandPerry.ThecompositevelocityscaleisformedbythemaximumReynoldsshearstressandtheSchofieldPerryvelocityscaleaswellastheedgevelocityoftheboundarylayer.Theresultsoftheseexperimentsarepresentedinthispaper
