Experimental correlation for pipe flow drag reduction using relaxation time of linear flexible polymers in a dilute solution

Abstract

In this study, we investigate the drag reduction property of a linear flexible polymer, PEO (polyethylene oxide) in a fully turbulent pipe flow. The aim of this study is to develop a correlation to predict the drag reduction using the Weissenberg number, a dimensionless number related to the relaxation time of the polymer and the polymer concentration in dilute solutions. The physical meaning of the relaxation time of polymers and overlap concentration between the dilute and semi-dilute polymer solution are clarified. A higher polymer concentration, Reynolds number, and Weissenberg number lead to an increasing drag reduction. A semi-empirical correlation to predict the drag reduction with two dimensionless variables mentioned above is established and can predict the experimental data in this work and other previous works well. Previous correlations that use Reynolds number often require high flow velocity or large pipes in the experimental setup to predict drag reduction in large-scale industrial applications, which involves extra cost and potential safety issues. The current new correlation method uses relatively low velocities to avoid the problems mentioned above. K E Y W O R D Sdrag reduction, pipe flow, polymer, relaxation time, Weissenberg number

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“…Sutterby fluid model is one type of non-Newtonianism fluid 92 , and it describes the viscosity of dilute polymer solutions 93 . Polymer solutions have been applied in related industrial phenomena or products, such as turbulent pipe flows 94,95 , stability of polymer jets 96,97 , and oil recovery enhancement 98,99 . The heat and mass transfer withinside the flow of magnetohydrodynamics (MHD) Sutterby nanofluid over a stretching cylinder, with the impact of temperature-structured thermal conductivity have been explored by Sohail et al 100 and Raza et al 101 .…”

Effect of Salinity on Drag Reduction of Additives and Mixtures under Turbulent Flow

“…Although the presence of salt in this work would increase the threshold values reported by Ushida et al, 62 the concentrations tested here are still significantly higher than the threshold values. With regards to the DR of the various polymers in brine, which were found to be generally lower than those found for tap water, it is worth noting that there is a possible connection between the reduction in viscosity and the decrease in DR. For instance, in the correlation developed by Zhang et al 63 between DR and Weissenberg number, a higher solvent viscosity, which increases the relaxation time, was linked to a higher Weissenberg number, leading to increased DR. With the exception of the PEO 50 ppm case, this correlation between viscosity and DR is consistent with our findings. It suggests that the decrease in DR with the addition of salt is a direct consequence of reduction in viscosity.…”

Investigation on the influence of sulfonic substitution in polyacrylamides for minimizing drag in turbulent flow of slickwater fluids

“…[46][47][48][49][50] The improved drag reduction performance of these functionalized polymers was explained based on the variation in the polymer relaxation time the presence of monovalent/divalent brines. 51,52 Moreover, the drag reduction (%DR) performance can also be altered by changing the polymer concentration in the fluid. [53][54][55] The latest studies have emphasized the development of hydrophobic associative water-soluble polymers (HAWSPs) containing comonomers of acrylamide and acrylic acid, as well as hydrophobic associative functional substitutions, for the purpose of drag reduction applications.…”