ExperimentalandNumericalInvestigationsofAxisymmetricTurbulenceDerTechnischenFakultat¨ derUniversitat¨ Erlangen N urnber¨ gzurErlangungdesGradesDOKTOR INGENIEURvorgelegtvon¨Ozgur¨ Ertunc¸Erlangen,2007AlsDissertationgenehmigtvonderTechnischenFakultat¨ derUniversitat¨ Erlangen N urnber¨ gTagderEinreichtung: 10.07.2006TagderPromotion: 08.11.2006Dekan: Prof. Dr. Ing. AlfredLeipertzBerichterstatter: Prof. Dr. Dr. h.c. Franz. DurstProf. Dr. Ing. Dr. Ing. habil. C.TropeaAcknowledgmentsDuring the Summer Academy 1997, I met with Prof. Dr. Dr. h.c. Franz Durst for thefirsttime. Atthattime,wehadanicetalkontheimpactoffluidmechanicsonourdailylifeandtheresearchactivitiesatLSTM Erlangen,whichfindusuallydirectapplicationin important aspects of our society, such as industry, environment and science. Atthat time, his approach to fluid mechanics encouraged me to pursue my PhD workat LSTM Erlangen. However, this occasion would never be possible when Prof. Dr.Gurb¨ uz¨ Atagund¨ uz¨ encouragedmetojointheSummerAcademy.I have many reasons to be grateful to Prof. Dr. Dr. h.c. Franz Durst: most impor-tantlyforthefreeresearchenvironmentthatheandhisco workersgeneratedatLSTM Erlangeninwhichonecanlearntomakescientificresearch,todevelopideas,torealizethese ideas and to take responsibility.