Theoretical and experimental study of the dependence of transient pipe friction on turbulence dynamics

Improvements in the accuracy of predicting unsteady flows in pipelines have opened up new research areas such as transient-based leak detection that, in turn, are demanding even greater accuracy in flow modelling. One of the biggest barriers to progress is the simulation of unsteady skin friction on pipe walls. There have been impressive intuitive advances in the past decade, but it is generally recognised that further success is hampered by inadequate understanding of turbulence dynamics in transient pipe flows. The proposed project brings together an international team of specialists in (i) turbulence, (ii) transient flow analysis and (iii) transient flow experiments in a focussed bid to break the understanding barrier.Current knowledge is so inadequate that we are not even able to predict the directions of axial shear forces on pipe walls (let alone their amplitudes) during transient events such as the propagation of pressure waves. A full discussion session was set aside for this topic at an international conference in March 2004. Experts from many countries around the world shared ideas for future research aimed at reducing the uncertainty. This research proposal focusses on the most promising way forward, namely studying dynamic interactions between axial, radial and circumferential components of turbulence in rapidly changing pipe flows. Highly detailed numerical and experimental studies in the UK and Italy will feed into assessments of 1-D numerical models used by pipe flow analysts.