Large-Eddy simulation of turbulent pipe flow of power-law fluids

• LES of turbulent pipe flows of power-law fluids in a cylindrical pipe was performed.
• The effects of various flow indexes and Reynolds numbers were considered.
• Correlations for peak positions of RMS of velocity fluctuations and kinetic energy are proposed.
• Profiles of higher-order statistics (skewness, flatness) are plotted.
• With increasing n, the apparent viscosity increases for y+ < 5 and decreases after y+ ≈ 35.

Fully developed turbulent flows of power-law fluids in a cylindrical stationary pipe are investigated numerically by the use of large eddy simulation (LES) for various power law index (0.5⩽n⩽1.40.5⩽n⩽1.4) at different Reynolds numbers (4000⩽Res4000⩽Res ⩽ 12,000). To validate the present computations, the predictions are compared to the results reported in the archival literature for laminar and turbulent flows. The LES predictions agree reasonably favourably with the findings of the literature. The log-region of the mean axial velocity profile expands with increasing ResRes and decreasing power-law index n  . The predicted friction factor for n⩽1n⩽1 at Res=4000Res=4000 is slightly overestimated in comparison with Dodge and Metzner correlation, and is better interpolated by Gomes correlation. With increasing n   the apparent viscosity increases close to the wall and decreases for y+>30y+>30. This implies that the turbulent fluctuations develop and are more intense further from the wall when n>1n>1 and closer to the wall when n<1n<1. The influence of ResRes and n on the higher-order statistics (skewness and flatness) is analyzed. Visualizations of the instantaneous filtered velocity fields exhibit turbulent patterns which develop more as n increases.