Frictional Resistance of Flat Plates in Dilute Polymer Solutions

1973 ◽  
Vol 17 (04) ◽  
pp. 227-240
Author(s):  
L. Landweber ◽  
M. Poreh
Keyword(s):  
Drag Reduction ◽  
Frictional Resistance ◽  
Velocity Profiles ◽  
Experimental Result ◽  
Flat Plates ◽  
Law Of The Wall ◽  
Family Of Curves ◽  
Maximum Drag Reduction ◽  
The Law ◽  
Two Parameter

For a flat plate moving in a dilute polymer solution, effects on boundary-layer characteristics, shear stress, drag reduction and maximum drag reduction are considered for polymers which satisfy the Meyer-Elata law. Results are derived from a model in which the velocity profiles satisfy the law-of-the-wall and a velocity-defect law, and the polymer has no effect in the range in which the latter law is valid. It is also assumed that the polymer affects the law of variation of the mixing length, and a family of velocity profiles representing this effect is adopted. This model then yields a curve of maximum drag reduction as well as a two-parameter family of curves of drag reduction, consequences of the nonoverlapping or overlapping of the two velocity-profile laws. The results are compared with those of Granville for drag reduction, and with the predicted curve of Virk-Granville and an experimental result of Levy and Davis for maximum drag reduction.

Fabrication of Micro-Nano Structured Super-Hydrophobic Surface and Drag Reduction in Channels

2012 ◽  
Vol 519 ◽  
pp. 297-302 ◽  
Author(s):  
Cheng Song Fu ◽  
Dang Chao Cao ◽  
Zhen Zhang ◽  
Si Lu ◽  
Zhao Hui Yao
Keyword(s):  
Drag Reduction ◽  
Hydrophobic Surface ◽  
Experimental Result ◽  
Large Area ◽  
Nano Structure ◽  
Macro Scale ◽  
Fly Ash Cenosphere ◽  
Maximum Drag Reduction ◽  
New Processing ◽  
Flow Drag

In order to research the characteristic of flow drag reduction on large area super-hydrophobic surface, we have been designed a new processing technology to construct a micro-nano structure super-hydrophobic surfaces which formed by surface nanometer fly ash cenosphere. The experimental result of the flow drag reduction tested on macro-scale channel in laminar flow is very well, and the maximum drag reduction is 25.6%.

Research on Drag Reduction Performance of Bionic Shark Gill Jet Surface

2014 ◽  
Vol 654 ◽  
pp. 57-60 ◽  
Author(s):  
Zhao Gang ◽  
Fang Li ◽  
Wei Xin Liu ◽  
Ming Ming Liu ◽  
Hong Shi Bi
Keyword(s):  
Numerical Simulation ◽  
Boundary Layer ◽  
Drag Reduction ◽  
Fluid Velocity ◽  
Reduction Rate ◽  
Frictional Resistance ◽  
Normal Velocity ◽  
Main Field ◽  
Maximum Drag Reduction ◽  
Pressure Resistance

According to the problem of bionic shark gill jet can reduce friction on shark surface, a model of bionic jet surface was established based on shark surface was analyzed by measurements, and its numerical simulation was processed by using RNG k-ε turbulence model. The results show that: the gill jet can reduce frictional resistance on shark surface, and the best drag reduction can be got when the speed of main field is 5m/s, furthermore the maximum drag reduction rate can be up to 17.15%. The pressure of jet hole upstream is reduced which due to the barrier to the facing fluid by the jet, so that the pressure resistance of jet surface is reduced as well. Besides, jet fluid is blocked in the boundary layer by mainstream fluid, which caused the fluid velocity of jet hole downstream is reduced, the thickness of boundary layer is increased, and the normal velocity gradient of wall is reduced, so as to achieve the effect of drag reduction.

Drag Reduction and Velocity Profiles Distribution of Crude Oil Flow in Spiral Pipes

2015 ◽  
Vol 9 (1) ◽  
pp. 1 ◽  
Author(s):  
Yanuar Yanuar ◽  
Kurniawan T. Waskito ◽  
Gunawan Gunawan ◽  
Budiarso Budiarso
Keyword(s):  
Drag Reduction ◽  
Crude Oil ◽  
Velocity Profiles ◽  
Oil Flow

scholarly journals Resistance reduction on trimaran ship model by biopolymer of eel slime

2015 ◽  
Vol 12 (2) ◽  
pp. 95-102
Author(s):  
Y. Yanuar ◽  
G. Gunawan ◽  
M. A. Talahatu ◽  
R. T. Indrawati ◽  
A. Jamaluddin
Keyword(s):  
Drag Reduction ◽  
Frictional Resistance ◽  
Skin Surface ◽  
Fish Skin ◽  
Total Drag ◽  
Towing Tank ◽  
Ship Model ◽  
Resistance Reduction ◽  
Towing Tank Test ◽  
Tank Test

Resistance reduction in ship becomes an important issue to be investigated. Energy consumption and its efficiency are related toward drag reduction. Drag reduction in fluid flow can be obtained by providing polymer additives, coating, surfactants, fiber and special roughness on the surface hull. Fish skin surface coated with biopolymers viscous fluid (slime) is one method in frictional resistance reduction. The aim of this is to understanding the effect of drag reduction using eel slime biopolymer in unsymmetrical trimaran ship model. The Investigation was conducted using towing tank test with variation of velocity. The dimension of trimaran model are L = 2 m, B = 0.20 m and T = 0.065 m. The ship model resistance was precisely measured by a load cell transducer. The comparison of resistance on trimaran ship model coated and uncoated by eel slime are shown on the graph as a function of the total drag coefficient and Froude number. It is discovered the trimaran ship model by eel slime has higher drag reduction compared to trimaran with no eel slime at similar displacement. The result shows the drag reduction about 11 % at Fr 0.35.

On the criteria for reverse transition in a two-dimensional boundary layer flow

1969 ◽  
Vol 35 (2) ◽  
pp. 225-241 ◽  
Author(s):  
M. A. Badri Narayanan ◽  
V. Ramjee
Keyword(s):  
Longitudinal Velocity ◽  
Outer Region ◽  
Transition Process ◽  
Velocity Profiles ◽  
Wall Region ◽  
Two Dimensional ◽  
Mean Velocity ◽  
Law Of The Wall ◽  
Reverse Transition ◽  
Turbulence Decay

Experiments on reverse transition were conducted in two-dimensional accelerated incompressible turbulent boundary layers. Mean velocity profiles, longitudinal velocity fluctuations $\tilde{u}^{\prime}(=(\overline{u^{\prime 2}})^{\frac{1}{2}})$ and the wall-shearing stress (TW) were measured. The mean velocity profiles show that the wall region adjusts itself to laminar conditions earlier than the outer region. During the reverse transition process, increases in the shape parameter (H) are accompanied by a decrease in the skin friction coefficient (Cf). Profiles of turbulent intensity (u’2) exhibit near similarity in the turbulence decay region. The breakdown of the law of the wall is characterized by the parameter \[ \Delta_p (=\nu[dP/dx]/\rho U^{*3}) = - 0.02, \] where U* is the friction velocity. Downstream of this region the decay of $\tilde{u}^{\prime}$ fluctuations occurred when the momentum thickness Reynolds number (R) decreased roughly below 400.

Drag Reduction of the Flow Past a Circular Cylinder in Surfactant Solution

2001 ◽  
Author(s):  
Satoshi Ogata ◽  
Keizo Watanabe
Keyword(s):  
Circular Cylinder ◽  
Drag Reduction ◽  
Sodium Salicylate ◽  
Tap Water ◽  
Pressure Coefficient ◽  
Surfactant Solution ◽  
Reduction Ratio ◽  
Number Range ◽  
Surfactant Solutions ◽  
Maximum Drag Reduction

Abstract The flow around a circular cylinder in surfactant solution was investigated experimentally by measurement of the pressure and velocity profiles in the Reynolds number range 6000 < Re < 50000. The test surfactant solutions were aqueous solutions of Ethoquad O/12 (Lion Co.) at concentrations of 50, 100 and 200 ppm, and sodium salicylate was added as a counterion. It was clarified that the pressure coefficient of surfactant solutions in the range of 10000 < Re < 50000 at the behind of the separation point was larger than that of tap water, and the separation angle increased with concentration of the surfactant solution. The velocity defect in surfactant solutions behind a circular cylinder was smaller than those in tap water. The drag coefficients of a circular cylinder in surfactant solutions were smaller than those of tap water in the range 10000 < Re < 50000, and no drag reduction occurred at Re = 6000. The drag reduction ratio increased with increasing concentration of surfactant solution. The maximum drag reduction ratio was approximately 35%.

Velocity Profiles During Drag Reduction

1969 ◽  
pp. 233-250 ◽  
Author(s):  
G. K. Patterson ◽  
G. L. Florez
Keyword(s):  
Drag Reduction ◽  
Velocity Profiles

scholarly journals Dynamics of viscoelastic pipe flow at low Reynolds numbers in the maximum drag reduction limit

2019 ◽  
Vol 874 ◽  
pp. 699-719 ◽  
Author(s):  
Jose M. Lopez ◽  
George H. Choueiri ◽  
Björn Hof
Keyword(s):  
Drag Reduction ◽  
Turbulent Flows ◽  
Pipe Flow ◽  
Domain Size ◽  
Reynolds Numbers ◽  
Weissenberg Number ◽  
Pipe Length ◽  
Low Reynolds Numbers ◽  
Maximum Drag Reduction ◽  
Low Reynolds

Polymer additives can substantially reduce the drag of turbulent flows and the upper limit, the so-called state of ‘maximum drag reduction’ (MDR), is to a good approximation independent of the type of polymer and solvent used. Until recently, the consensus was that, in this limit, flows are in a marginal state where only a minimal level of turbulence activity persists. Observations in direct numerical simulations at low Reynolds numbers ($Re$) using minimal sized channels appeared to support this view and reported long ‘hibernation’ periods where turbulence is marginalized. In simulations of pipe flow at $Re$ near transition we find that, indeed, with increasing Weissenberg number ($Wi$), turbulence expresses long periods of hibernation if the domain size is small. However, with increasing pipe length, the temporal hibernation continuously alters to spatio-temporal intermittency and here the flow consists of turbulent puffs surrounded by laminar flow. Moreover, upon an increase in $Wi$, the flow fully relaminarizes, in agreement with recent experiments. At even larger $Wi$, a different instability is encountered causing a drag increase towards MDR. Our findings hence link earlier minimal flow unit simulations with recent experiments and confirm that the addition of polymers initially suppresses Newtonian turbulence and leads to a reverse transition. The MDR state on the other hand results at these low$Re$ from a separate instability and the underlying dynamics corresponds to the recently proposed state of elasto-inertial turbulence.

Maximum Drag Reduction Asymptote of Polymeric Fluid Flow in Coiled Tubing

2008 ◽  
Vol 131 (1) ◽  
Author(s):  
Subhash N. Shah ◽  
Yunxu Zhou
Keyword(s):  
Drag Reduction ◽  
Oil And Gas ◽  
Guar Gum ◽  
Oil And Gas Industry ◽  
Flow Loop ◽  
Polymeric Fluids ◽  
Curvature Ratio ◽  
Coiled Tubing ◽  
Industry Applications ◽  
Maximum Drag Reduction

This study experimentally investigates the drag reduction characteristics of the most commonly used polymer fluids in coiled tubing applications. The flow loop employed consists of 12.7mm straight and coiled tubing sections. The curvature ratio (a∕R, where a and R are the radii of the tubing and the reel drum, respectively) investigated is from 0.01 to 0.076, which covers the typical curvature ratio range encountered in the oil and gas industry applications. Fluids tested include xanthan gum, guar gum, and hydroxypropyl guar at various polymer concentrations. It is found that the drag reduction in coiled tubing is significantly lower than that in straight tubing, probably due to the effect of secondary flow in curved geometry. The onset of drag reduction is also found to be delayed as the curvature ratio was increased. A correlation for the maximum drag reduction (MDR) asymptote in coiled tubing is developed. When the curvature ratio is set to zero, the new correlation reduces to the well-known Virk’s MDR asymptote for dilute polymer solutions in straight pipes. A new drag reduction envelope is proposed for the analysis of drag reduction behavior of polymeric fluids in coiled tubing. Application of the new drag reduction envelope is also discussed.

Sign in / Sign up

Export Citation Format

Share Document