Resolving Reynolds riddle: the critical point of pipe flow

At low speeds fluid flows are laminar and they turn turbulent as the flowrate is increased. The point at which turbulence first occurs cannot easily be predicted even for flows in very simple geometries. Ever since an investigation by Osborne Reynolds in the 19th century scientists tried to determine this point for the fundamentally most important case: pipe flow. Despite many attempts this problem remained unresolved for over 125 years. Scientists from the Max Planck Institute for Dynamics and Selforganization and colleagues from the University of Warwick could finally answer this question.