Journal ArticleDOI
Development of local turbulent drag reduction due to nonuniform polymer concentration
W. D. McComb,L. H. Rabie +1 more
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In this paper, the authors found that the turbulent drag reduction produced by injection of polymer at the centerline of a pipe flow was increased with streamwise distance from the injection point, due to radial dispersion of the injected polymer.Abstract:
Turbulent drag reduction produced by injection of polymer at the centerline of a pipe flow was found to increase with streamwise distance from the injection point. This was due to radial dispersion of the injected polymer. A tentative relationship between the two is proposed.read more
Citations
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Journal ArticleDOI
Mechanics and Prediction of Turbulent Drag Reduction with Polymer Additives
TL;DR: A review of recent progress in understanding and predicting polymer drag reduction (DR) in turbulent wall-bounded shear flows is provided in this paper, where numerical simulations of viscoelastic turbulent flows and detailed turbulence measurements in flows of dilute polymer solutions using laser-based optical techniques.
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Turbulent channel flow near maximum drag reduction: simulations, experiments and mechanisms
PK Ptasinski,Bendiks Jan Boersma,Ftm Nieuwstadt,MA Martien Hulsen,van den Bhaa Ben Brule,Jcr Hunt +5 more
TL;DR: In this article, a simulation of a turbulent channel flow is presented, where the polymers are modelled as elastic dumbbells using the FENE-P model and the simulation results show that at approximately maximum drag reduction the slope of the mean velocity profile is increased compared to the standard logarithmic profile in turbulent wall flows.
Journal ArticleDOI
The onset of drag reduction by dilute polymer additives, and the maximum drag reduction asymptote
TL;DR: In this paper, the de Gennes elastic theory is considered in the context of pipe flow and the so-called maximum drag reduction (MDR) asymptote is investigated.
Journal ArticleDOI
Wall-layer structure and drag reduction
TL;DR: In this article, the authors measured the spanwise spacing and bursting rate of the wall-layer structure of a turbulent channel flow of water and showed that when the additives are confined entirely to the linear sublayer of the water flow and there is no evidence of drag reduction, the span-wise streak spacing increases and the average bursting rate decreases.
Journal ArticleDOI
Roles of drag reducing polymers in single- and multi-phase flows
TL;DR: In this article, a review of the use of polymers as drag reducing agents in turbulent single and multiphase flows is presented. But, despite the voluminous works on drag reducing polymers, there are no universally accepted models and hence the mechanisms of drag reduction by polymers.
References
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Journal ArticleDOI
Drag reduction fundamentals
TL;DR: In this paper, the effects of dilute solutions of linear, random-coiling macromolecules in turbulent pipe flow is reviewed. And the experimental evidence is emphasized in three sections concerned with the graphical display of established features of the phenomenon, data correlation and analysis, and the physical mechanism of drag reduction.
Journal ArticleDOI
Injection of a Drag‐Reducing Fluid into Turbulent Pipe Flow of a Newtonian Fluid
TL;DR: In this article, a series of experiments, in which dilute solutions of drag reducing fluids were injected into turbulent pipe flow of a Newtonian fluid, were performed in order to determine whether the presence of the additive only in the wall region could produce significant local shear stress reduction.
Journal ArticleDOI
Drag reduction by polymer threads
J. Vleggaar,M. Tels +1 more
TL;DR: In this article, a novel type of drag reduction is described which is caused by long polymer threads in turbulent flow, formed by axial injection of a concentrated, visco-elastic, polymer solution and persis over a distance of more than 200 tube diameters.
Journal ArticleDOI
Mechanical mixing of polymer additive in turbulent drag reduction
TL;DR: In this paper, the concept of homogeneous and heterogeneous drag reduction was unified for pipe flow and was shown to unify the concepts of heterogeneous and homogeneous Drag Reduction.