A low-Reynolds-number k–ε model for polymer drag-reduction prediction in turbulent pipe flow

Abstract

Pipeline transport at high Reynolds number can result in significant turbulent losses. One of the most effective methods for turbulent drag reduction is adding a very small amount of polymer drag-reducing agent to the pipeline. However, due to the complex interaction between polymers and turbulence, turbulence models incorporating polymer additives remain to be studied and developed. In the present work, we investigated the turbulence model using Reynolds averaged numerical simulation (RANS) to describe polyacrylamide drag reduction flow. A low-Reynolds-number k–ε model in turbulent flow has been developed by considering the concentration and type of polymers, which can be applied for polymer drag reduction prediction in the pipe. Mean velocity profile U_f, turbulent intensity, turbulent kinetic energy k, and turbulent dissipation rate ε in the regions of viscous sublayer, buffer layer and logarithmic layer have been predicted with various concentration θ, Reynolds number Re, degradation degrees, and changing laws of these factors have been revealed with wall distance. The developed turbulence model showed a good capability to qualitatively forecast mean velocity profile, turbulent intensity, turbulent kinetic energy, and turbulent dissipation rate, and the prediction error between the experimental and simulated values falls along the y = x curve, which can be used for the investigation and prediction of varies water-soluble, oil-soluble polymers in turbulent drag reduction flow in pipes with other parameters such as pipe diameter, pipe length, and the Reynolds number.