Wall Pressure in Developing Turbulent Pipe Flows

Abstract

Velocity fluctuations are widely used to identify the behavior of developing turbulent flows. The pressure on the other hand, which is strongly coupled with the gradient of the mean velocity and fluctuations, is less explored. In this study, we report the results of wall pressure measurements for the development of pipe flow at high Reynolds numbers along the axial direction. It is found that the pressure fluctuations increase exponentially along the pipe with a self-similarity scaling. The exponential growth of the pressure fluctuations along the pipe saturates after reaching a critical position around 50 diameters from the inlet. It qualitatively agrees with the critical position usually adopted for fully developed turbulence, which was obtained from earlier velocity fluctuations at various locations along the pipe centerline. Results also show that the exponential growth of the pressure fluctuations is weakly affected by the presence of ring obstacles placed close to the pipe inlet. Finally, it is found that the pressure fluctuations decrease as a function of Reynolds number, contrary to the boundary layer flow.