Streamwise Auto-Correlation Analysis in Turbulent Pipe Flow Using Particle Image Velocimetry at High Reynolds Numbers

Abstract

This preliminary study focuses on determining the lengths of turbulent pipe flow structures at \(\textit{Re}_{b} \approx 60,000\) and 140, 000 using auto-correlation analysis in streamwise direction considering velocity fluctuations, where \(\textit{Re}_{b}\) is the Re-number based on bulk velocity. These structures are usually represented in terms of wavelengths \(\lambda \) or wavenumbers k. The current investigations on such turbulent structures including both large-scale motions (LSM) and very large-scale motions (VLSM) showed that the streamwise extension of these structures is highly dependent on the Reynolds number. Hence, the Cottbus large pipe (CoLaPipe) as a high Reynolds number test facility is being used to understand the physical processes and dynamics of such structures. These turbulence structures have been investigated using particle image velocimetry (PIV) to validate and compare earlier results obtained utilizing hot-wire anemometry (HWA).