Turbulent-Drag Reduction by Oblique Wavy Wall Undulations

2019 ◽  
pp. 545-551
Author(s):  
S. Ghebali ◽  
S. I. Chernyshenko ◽  
M. A. Leschziner
Keyword(s):  
Drag Reduction ◽  
Wavy Wall ◽  
Turbulent Drag Reduction ◽  
Turbulent Drag

scholarly journals Analysis of anisotropically permeable surfaces for turbulent drag reduction

2017 ◽  
Vol 2 (11) ◽  
Author(s):  
Nabil Abderrahaman-Elena ◽  
Ricardo García-Mayoral
Keyword(s):  
Drag Reduction ◽  
Turbulent Drag Reduction ◽  
Turbulent Drag

scholarly journals Fibre-induced drag reduction

2008 ◽  
Vol 602 ◽  
pp. 209-218 ◽  
Author(s):  
J. J. J. GILLISSEN ◽  
B. J. BOERSMA ◽  
P. H. MORTENSEN ◽  
H. I. ANDERSSON
Keyword(s):  
Experimental Data ◽  
Numerical Simulation ◽  
Reynolds Number ◽  
Drag Reduction ◽  
Elastic Layer ◽  
Turbulent Drag Reduction ◽  
Rigid Polymer ◽  
Fibre Concentration ◽  
Induced Drag ◽  
Turbulent Drag

We use direct numerical simulation to study turbulent drag reduction by rigid polymer additives, referred to as fibres. The simulations agree with experimental data from the literature in terms of friction factor dependence on Reynolds number and fibre concentration. An expression for drag reduction is derived by adopting the concept of the elastic layer.

scholarly journals Turbulent drag reduction in a dilute polymeric solution flowing through a fiber-implanted circular pipe.

1988 ◽  
Vol 21 (4) ◽  
pp. 441-443
Author(s):  
HIROTSUGU HATTORI ◽  
TOMOO YAMAUCHI ◽  
SEIICHI TANABE ◽  
HIDEOMI MATSUDA
Keyword(s):  
Drag Reduction ◽  
Circular Pipe ◽  
Turbulent Drag Reduction ◽  
Polymeric Solution ◽  
Turbulent Drag

Turbulent drag reduction by spanwise oscillations of a ribbed surface

2013 ◽  
Vol 48 (4) ◽  
pp. 461-470 ◽  
Author(s):  
I. S. Vodop’yanov ◽  
N. V. Nikitin ◽  
S. I. Chernyshenko
Keyword(s):  
Drag Reduction ◽  
Turbulent Drag Reduction ◽  
Turbulent Drag

scholarly journals Turbulent drag reduction by polymer additives in parallel-shear flows

2017 ◽  
Vol 827 ◽  
Author(s):  
Bayode E. Owolabi ◽  
David J. C. Dennis ◽  
Robert J. Poole
Keyword(s):  
Drag Reduction ◽  
Cross Sections ◽  
Shear Flows ◽  
Extensional Flow ◽  
Relaxation Times ◽  
Weissenberg Number ◽  
Mechanical Degradation ◽  
Turbulent Drag Reduction ◽  
Time Resolved ◽  
Turbulent Drag

In this study, we experimentally investigate the turbulent drag-reduction (DR) mechanism in flow through ducts of circular, rectangular and square cross-sections using two grades of polyacrylamide in aqueous solution having different molecular weights and various semidilute concentrations. Specifically, we explore the relationship between drag reduction and fluid elasticity, purposely exploiting the mechanical degradation of polymer molecules to vary their rheological properties. We also obtain time-resolved velocity data for various DR levels using particle image velocimetry and laser Doppler velocimetry. Elasticity is quantified via relaxation times determined from uniaxial extensional flow using a capillary breakup apparatus. A plot of DR against Weissenberg number ($Wi$) is found to approximately collapse the data, with the onset of DR occurring at $Wi\approx 0.5$ and the maximum drag-reduction asymptote being approached for $Wi\gtrsim 5$. Thus quantitative predictions of DR in a range of shear flows can be made from a single measurable material property of a polymer solution, at least for this particular flexible linear polymer.

The influence of polymer conformation on turbulent drag reduction

AIChE Journal ◽  
1975 ◽  
Vol 21 (5) ◽  
pp. 1027-1029 ◽  
Author(s):  
Daniel White ◽  
R. J. Gordon
Keyword(s):  
Drag Reduction ◽  
Polymer Conformation ◽  
Turbulent Drag Reduction ◽  
Turbulent Drag
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