Influence of distributed addition of a polymer solution on the characteristics of a turbulent boundary layer

1984 ◽  
Vol 18 (5) ◽  
pp. 706-712
Author(s):  
V. A. Aleksin ◽  
A. G. Mikhailu ◽  
V. N. Pilipenko
Keyword(s):  
Boundary Layer ◽  
Turbulent Boundary Layer ◽  
Polymer Solution

Concentration flux measurements in a polymer drag-reduced turbulent boundary layer

2010 ◽  
Vol 644 ◽  
pp. 281-319 ◽  
Author(s):  
V. S. R. SOMANDEPALLI ◽  
Y. X. HOU ◽  
M. G. MUNGAL
Keyword(s):  
Boundary Layer ◽  
Turbulent Boundary Layer ◽  
Flat Plate ◽  
Polymer Solution ◽  
Quantitative Measure ◽  
Turbulent Dispersion ◽  
Wall Region ◽  
Polymer Injection ◽  
Turbulent Schmidt Number ◽  
Flux Measurements

The drag-reducing action of dilute solutions of long-chain polymers in a flat-plate turbulent boundary layer is studied using particle imaging velocimetry (PIV) and planar laser induced fluorescence (PLIF). The results are used to characterize and quantify the spatial distribution of the injected polymer solution and the downstream development of the DR along the flat plate. The two techniques were used simultaneously to document and study the spread of the injected polymer solution and the resulting changes in the structure and statistics of the turbulence in the boundary layer. The PLIF images provide a qualitative and quantitative measure of the dispersion of the injected polymer solution. The mean and root mean square (r.m.s.) concentration profiles obtained using PLIF showed that the polymer greatly suppressed the turbulent dispersion in the near-wall region. The quantitative concentration measurements across the boundary layer, combined with simultaneous velocity measurements, are used to obtain concentration flux measurements in the boundary layer and are used to study the effect of the turbulence on the dispersion of the injected polymer. The variation of the fluxes with concentration of the injected polymer solutions and with increasing downstream distance is also studied and documented. The action of the polymer is to reduce the streamwise fluxes in the boundary layer, the suppression increasing with concentration. Further, the fluxes are also used to estimate the turbulent Schmidt number (ScT) for the drag-reduced flow. For the polymer injection experiments, the ScT are all greater than unity with the highest magnitude measured to be around 6, with the magnitude increasing with increasing concentration of the injected solutions. However, for each experiment, the estimated ScT decreases along the length of the flat plate reflecting the loss of polymer effectiveness.

scholarly journals Modification of turbulent boundary layer coherent structures with drag reducing polymer solution

2020 ◽  
Vol 32 (1) ◽  
pp. 015107 ◽  
Author(s):  
Yasaman Farsiani ◽  
Zeeshan Saeed ◽  
Balaji Jayaraman ◽  
Brian R. Elbing
Keyword(s):  
Boundary Layer ◽  
Turbulent Boundary Layer ◽  
Polymer Solution ◽  
Coherent Structures ◽  
Drag Reducing Polymer

scholarly journals Specific features of coordinated variations in friction resistance and flow velocity profile in tubes at Toms effect

2021 ◽  
Vol 3 (397) ◽  
pp. 25-32
Author(s):  
V. Pavlovsky ◽  
◽  
О. Orlov ◽  
Keyword(s):  
Boundary Layer ◽  
Turbulent Boundary Layer ◽  
Velocity Profile ◽  
Flow Velocity ◽  
Polymer Solution ◽  
Polymer Solutions ◽  
Resistance Coefficient ◽  
Friction Resistance ◽  
General Law ◽  
Flow Velocity Profile

Object and purpose of research. Relationships between friction resistance coefficient and velocity distributions in the turbulent boundary layer of low-concentrated polymer solutions are investigated. These relationships are different from water because in polymer solutions the friction resistance at constant Reynolds numbers is additionally changed with solution concentrations. Materials and methods. The known experimental data on variations of the friction resistance coefficient and the velocity profiles in turbulent flows in circular tubes at changes in polymer solution concentrations. Main results. The general law of coordinated variations in friction resistance coefficient λ and flow velocity profile in the turbulent boundary layer depending on Reynolds number and polymer solution concentration. The flow models are validated, which describe the laws of velocity variations in all characteristic sections of boundary layer: laminar sublayer, buffer and logarithmic flow areas. A new non-dimensional number is introduced, which characterizes the ability of low concentrated water solutions of polymers to reduce the friction resistance. It is called the Toms effect parameter in the work. Conclusion. Results of the investigation will be useful in developing the theoretical methods for estimation of boundary layer characteristics in polymer solutions.

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