Study of Near Wall Coherent Flow Structures on Dimpled Surfaces Using Unsteady Pressure Measurements

摘要

Unsteady pressure measurements have been performed inside a spherical dimple in a narrow channel for turbulent flow at Re D  = 40,000 with the aim to study coherent vortex structures and to get a deep insight into flow physics. Results confirm the formation of asymmetric coherent vortex structures switching between two extreme positions. Analysis of the pressure temporal distributions and correlation functions shows the presence of the anti-phase motion inside the dimple. Typical power laws of the pressure fluctuation energy spectrum ω  − 1 and ω  − 7/3 are reproduced.