Suppressed diffusion of drag-reducing polymer in a turbulent boundary layer (Suppressed turbulent diffusion of drag reducing polymer solution in turbulent boundary layer, measuring concentration with laser-phototransistor unit)

1972 ◽  
Vol 6 (1) ◽  
pp. 46-50 ◽  
Author(s):  
JlN WU
Keyword(s):  
Boundary Layer ◽  
Turbulent Boundary Layer ◽  
Polymer Solution ◽  
Turbulent Diffusion ◽  
Drag Reducing Polymer

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

Diffusion of drag-reducing polymer solutions within a rough-walled turbulent boundary layer

2010 ◽  
Vol 22 (4) ◽  
pp. 045102 ◽  
Author(s):  
Brian R. Elbing ◽  
David R. Dowling ◽  
Marc Perlin ◽  
Steven L. Ceccio
Keyword(s):  
Boundary Layer ◽  
Turbulent Boundary Layer ◽  
Polymer Solutions ◽  
Drag Reducing Polymer

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.

Turbulent Diffusion Considering Turbulent Boundary Layer

1968 ◽  
Vol 16 (168) ◽  
pp. 16-22
Author(s):  
Nobuhiro UKEGUCHI ◽  
Hiroshi SAKATA ◽  
Yasuo IDE
Keyword(s):  
Boundary Layer ◽  
Turbulent Boundary Layer ◽  
Turbulent Diffusion

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

Boundary layer of a body of revolution in a drag-reducing polymer solution

1982 ◽  
Vol 16 (3) ◽  
pp. 355-361
Author(s):  
V. B. Amfilokhiev ◽  
V. V. Droblenkov ◽  
G. I. Kanevskii ◽  
N. P. Mazaeva
Keyword(s):  
Boundary Layer ◽  
Polymer Solution ◽  
Body Of Revolution ◽  
Drag Reducing Polymer

Turbulent diffusion and degradation of polymer molecules in a pipe and boundary layer

1979 ◽  
Vol 94 (3) ◽  
pp. 561-576 ◽  
Author(s):  
L. I. Sedov ◽  
V. A. Ioselevich ◽  
V. N. Pilipenko ◽  
N. G. Vasetskaya
Keyword(s):  
Boundary Layer ◽  
Molecular Weight ◽  
Turbulent Boundary Layer ◽  
Pipe Flow ◽  
Turbulent Diffusion ◽  
Water Soluble ◽  
Polymer Molecular Weight ◽  
Polymer Injection ◽  
Polymer Molecules ◽  
Flow Experiments

Results from a series of pipe-flow experiments using a range of water-soluble drag-reducing polymers are presented. Degradation has been investigated by means of multiple passes of the solutions through a pipe. A theory predicting drag reduction in pipe flow has been devised which agrees with the experimental results. Changes in polymer molecular weight due to degradation are taken into account. The analysis is then applied to a turbulent boundary layer with polymer injection.

Turbulent suspension of sediments in the deep sea

1990 ◽  
Vol 331 (1616) ◽  
pp. 167-181 ◽  
Keyword(s):  
Boundary Layer ◽  
Turbulent Boundary Layer ◽  
Suspended Sediment ◽  
Turbulent Diffusion ◽  
Local Equilibrium ◽  
Suspended Sediments ◽  
High Energy ◽  
Benthic Boundary Layer ◽  
Nepheloid Layer ◽  
Sediment Distribution

The high-energy benthic boundary layer experiment demonstrated the existence of high energy events capable of suspending large amounts of sediment at the base of the Nova Scotian Rise. The currents that cause these storms are episodic pulses of 25-35 cm s -1 flows lasting four to seven days. The build up and decay of the currents is too rapid for local equilibrium of the suspended sediment distribution to be achieved. Therefore, a fully time-dependent model of the turbulent boundary layer and the suspended sediments was developed to describe the events in detail. The period of high flow is erosive for only a few hours. The surface erodible bed sediments are quickly removed. The dominant processes resulting in the development of the suspended sediment profile are then restricted to turbulent diffusion and entrainment. The depth of penetration of the suspended sediments into the water column is limited by stratification induced by suspended sediments. After the shear generated turbulence collapses most of the eroded sediment remained in suspension far above the expected ‘ equilibrium ’ height for a ‘ non-storm ’ turbulent boundary layer. Scaling arguments, and the model, show that fine clay particles kept in suspension by turbulent diffusion dominate settling during the low level turbulence present during ‘non-storm’ conditions. Level 2 and 2 1/2 energy closure models with stratification predict quite different structures of the nepheloid layer.

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