scholarly journals Polymer drag reduction in surfactant-contaminated turbulent bubbly channel flows

2021 ◽  
Vol 6 (10) ◽  
Author(s):  
Daulet Izbassarov ◽  
Zaheer Ahmed ◽  
Pedro Costa ◽  
Ville Vuorinen ◽  
Outi Tammisola ◽  
...  
Keyword(s):  
Drag Reduction ◽  
Channel Flows ◽  
Polymer Drag Reduction

High Reynolds Number Micro-Bubble and Polymer Drag Reduction Experiments

2008 ◽  
Author(s):  
Steven L. Ceccio ◽  
David R. Dowling ◽  
Marc Perlin ◽  
Michael Solomon
Keyword(s):  
Reynolds Number ◽  
Drag Reduction ◽  
High Reynolds Number ◽  
Polymer Drag Reduction ◽  
Micro Bubble ◽  
High Reynolds

“Negative roughness” and polymer drag reduction

1991 ◽  
Vol 11-11 (2-3) ◽  
pp. 142-146 ◽  
Author(s):  
J. W. Hoyt
Keyword(s):  
Drag Reduction ◽  
Polymer Drag Reduction

Drag reduction and turbulent structure in two-dimensional channel flows

1991 ◽  
Vol 336 (1640) ◽  
pp. 19-34 ◽  
Keyword(s):  
Shear Stress ◽  
Drag Reduction ◽  
Strain Rate ◽  
Reynolds Stress ◽  
Polymer Concentration ◽  
Turbulent Structure ◽  
Channel Flows ◽  
Channel Height ◽  
Normal Velocity ◽  
Two Dimensional

A two-component laser velocimeter has been used to determine the effect of wall strain rate, polymer concentration and channel height upon the drag reduction and turbulent structure in fully developed, low concentration, two-dimensional channel flows. Water flows at equal wall shear stress and with Reynolds numbers from 14430 to 34640 were measured for comparison. Drag reduction levels clearly depended upon wall strain rate, polymer concentration and channel height independently.However, most of the turbulent structure depended only upon the level of drag reduction. The slope of the logarithmic law of the wall increased as drag reduction increased. Similarly, the root-mean-square of the fluctuations in the streamwise velocity increased while the r.m.s. of the fluctuations in the wall-normal velocity decreased with drag reduction. The production of the streamwise normal Reynolds stress and the Reynolds shear stress decreased in the drag-reduced flows. Therefore it appears that the polymer solutions inhibit the transfer of energy from the streamwise to the wall-normal velocity fluctuations. This could occur through inhibiting the newtonian transfer mechanism provided by the pressure-strain correlation. In six drag-reducing flows, the sum of the Reynolds stress and the mean viscous stress was equal to the total shear stress. However, for the combination of highest concentration (5 p.p.m.), smallest channel height (25 mm) and highest wall strain rate (4000 s - 1 ), the sum of the Reynolds and viscous stresses was substantially lower than the total stress indicating the presence of a strong non-newtonian effect. In all drag-reducing flows the correlation coefficient for uv decreased as the axes of principal stress for the Reynolds stress rotated toward the streamwise and wall-normal directions.

Comparison of Turbulent Boundary Layer Profiles Modified With Injection or Uniform Concentration of Drag-Reducing Polymer Solution

2020 ◽  
Author(s):  
Brian R. Elbing
Keyword(s):  
Boundary Layer ◽  
Turbulent Boundary Layer ◽  
Drag Reduction ◽  
Polymer Concentration ◽  
Weissenberg Number ◽  
Polymer Injection ◽  
Von Karman ◽  
Polymer Properties ◽  
Polymer Drag Reduction ◽  
Von Kármán

Abstract The current study explores the influence of polymer drag reduction on the near-wall velocity distribution in a turbulent boundary layer. The classical view is that the polymers modify the intercept constant within the log-region without impacting the von Kármán coefficient, which results in the log-region being unaltered though shifted outward from the wall. However, it has been recently shown that this is not accurate, especially at high drag reduction (> 40%). Past work examining the von Kármán coefficient and intercept constant has shown that polymer properties must impact the deviations, but without any quantification of the dependence. This work reviews the literature to make estimates of the local polymer properties and then demonstrates that the scatter at HDR can be attributed to variations in the Weissenberg number. In addition, new polymer ocean results are incorporated and shown to be quite consistent with polymer injection results using the maximum polymer concentration to define the polymer properties.

scholarly journals FISH MUCUS:IN SITUMEASUREMENTS OF POLYMER DRAG REDUCTION

1981 ◽  
Vol 160 (3) ◽  
pp. 376-382 ◽  
Author(s):  
THOMAS L. DANIEL
Keyword(s):  
Drag Reduction ◽  
Polymer Drag Reduction
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