Drag Reduction of Polymer Solutions in a Pipe With a Highly Water-Repellent Wall

1999 ◽  
Author(s):  
Keizo Watanabe ◽  
Hiroshi Udagawa
Keyword(s):  
Pressure Drop ◽  
Laminar Flow ◽  
Drag Reduction ◽  
Polymer Solutions ◽  
Tap Water ◽  
Acrylic Resin ◽  
Water Repellent ◽  
Number Range ◽  
Surfactant Solutions ◽  
Laminar And Turbulent Flow

Abstract By applying a highly water-repellent wall pipe in the drag reduction of polymer solutions, a flow system in which drag reduction is obtained in both laminar and turbulent flow ranges has been realized. Experiments were carried out to measure the pressure drop in pipes with a highly water-repellent wall and an acrylic resin wall by means of a pressure transducer. The diameter of the pipe was 6mm. The polymer solutions tested were PE015 aqueous solutions in the concentration range of 30ppm∼1000ppm. The drag reduction ratio for laminar flow was about 11∼15%. To understand this effect, the pressure drop was measured by using surfactant solutions and degassed water, and by pressurizing tap water in the pipeline. It was shown that the laminar drag reduction does not occur in the case of surfactant solutions although degassed water and pressurizing tap water in the pipeline have no effect on the reduction. In the laminar flow range, the friction factor of a power-law fluid with fluid slip was analyzed by applying the modified boundary condition on fluid slip at the pipe wall, and the analytical results agree with the experimental results in the low Reynolds number range.

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%.

Drag Reduction in Three Distinctly Different Fluid Systems

1981 ◽  
Vol 21 (06) ◽  
pp. 663-669 ◽  
Author(s):  
Thomas R. Sifferman ◽  
Robert A. Greenkorn
Keyword(s):  
Pressure Drop ◽  
Drag Reduction ◽  
Polymer Solution ◽  
Flow Rate ◽  
Polymer Solutions ◽  
Tap Water ◽  
Smooth Wall ◽  
Two Phase ◽  
Fluid Systems ◽  
Flow Systems

Abstract Drag reduction was observed in three distinctly different flow systems-dilute polymer solutions, two-phase solid/liquid suspensions, and three-phase immiscible liquid/liquid flow with suspended solids - in relatively large-diameter pipes (0.027, 0.038, and 0.053 m). Galvanized pipes presented a rough wall, while glass provided a smooth wall and allowed for flow visualization. provided a smooth wall and allowed for flow visualization. By drag reduction, we mean that, for the same flow rate, there is less pressure drop per length of pipe than for the base fluid flowing, alone.Three polymers-sodium carboxymethylcellulose (CMC). polyethylene oxide (POLYOX(TM)), and guar gum) (Jaguar(TM)) were mixed with water to form solutions of various concentrations (from 0.001 to 0.3 wt%). Two nominal concentrations (5 to 10%) of silca sand also were suspended with either tap water or some of the polymers. Finally, white mineral oil and either tap water or polymer solutions were tested. Sand also was added to the oil system.Drag reductions of up to almost 80% were obtained for both the polymer systems and the oil system. Sand suspensions had a maximum of about 35% drag reduction in tap water. However, greatest reductions (more than 90% were attained with the polymer/sand suspensionsSince the sand in the polymer solutions reduced the drag even more than the polymers alone, it may be that the drag mechanism is additive and even may be the same type for both polymers and suspensions.Drag reduction occurs in the region near the wall and could occur in an intermediate layer zone that allows an effective slip velocity to result. Polymers showed significant deviation from the Newtonian velocity profiles.Less power was required to pump the polymers than water alone. Viscosity and normal stress data were obtained also. Introduction There are many interesting engineering applications of drag-reduction phenomena. For many flow situations in conduits, the use of a drag reduction agent (normally a viscoelastic soluble polymer) increases flow rate for the same pressure drop in diverse systems. Such as storm sewers, drilling operations, fire fighting, irrigation and living systems. External flows can be improved around ships and torpedoes. Proper design of solid/fluid systems to take advantage of the drag reduction associated with suspended solids can be used in transporting coal, raw sewage, and sediment. In two-phase liquid/liquid situations, such as hydraulic fracturing of oil wells and transportation of liquid petroleum. drag reduction associated with annular immiscible or emulsion flow can be used to advantage where exceptionally large reductions in pressure for a given flow rate result for viscous oils and water.To design systems to take advantage of lower energy requirements at the same flow rate, data are necessary (1) from systems large enough that diameter effects are absent, (2) at flow rates of sufficient velocity that the phenomena are present, and (3) on different systems phenomena are present, and (3) on different systems with varying physical properties. Such data re necessary to develop correlations, to understand flow mechanisms, and to develop mathematical models-all of which are necessary to interpolate and extrapolate the data for design of such flow systems. Previously, this type of data has not been available.Drag reductions is defined, at a given flow rate, as the pressure drop for a given system minus the pressure drop pressure drop for a given system minus the pressure drop for the base fluid divided by the pressure drop for the base fluid.In this paper, we report observations of drag-reduction phenomena in three distinctly different flow systems: (1) phenomena in three distinctly different flow systems:single-phase water, oil, and dilute polymer-water solutions;two-phase oil/water, oil/polymer solution, water/sand, and polymer solution/sand; andthree-phase oil/water/sand and oil/polymer solution/sand. The data were collected in 0.027- and 0.053-m Schedule 40 galvanized pipe and a 0.038-m-ID smooth-wall glass pipe. pipe. SPEJ P. 663

Flow of Surfactant Solutions Past a Circular Cylinder

2004 ◽  
Author(s):  
Yoshihisa Osano ◽  
Satoshi Ogata ◽  
Keizo Watanabe
Keyword(s):  
Reynolds Number ◽  
Circular Cylinder ◽  
Drag Reduction ◽  
Drag Coefficient ◽  
Tap Water ◽  
Surfactant Solution ◽  
Number Range ◽  
Surfactant Solutions ◽  
Reynolds Number Range ◽  
Trade Name

To clarify the effects of surfactant solutions on the drag coefficient of a circular cylinder, the flow past a circular cylinder was investigated in the Reynolds number range of 10 to 7,000 by measuring the drag and by visualizing flow. In addition, the flow pattern was simulated numerically to examine the effect of the viscoelasticity of the surfactant solution. Six cylinders with diameters between 2 and 20 mm were tested, and the ratio of length to diameter (l/d) was 12~48. The test surfactant solutions were aqueous solutions of oleyl-methyldihydroxyethyl ammonium chloride (trade name: Ethoquad O/12) in the concentration range of 50 to 200 ppm and sodium salicylate was added as a counterion. It was clarified that the drag coefficient of surfactant solutions increases comparing with that of tap water in the Reynolds number range of 1,000 < Re 3,000 and drag reduction occurs when Re > 3,000 for a cylinder diameter of 20 mm. The maximum drag reduction ratio was approximately 55% for 200 ppm solution at Re = 7,000. The flow visualization results showed that the drag of surfactant solutions increases because of the existence of the wide stagnant zone around the cylinder. This zone disappeared in the Reynolds number range in which drag reduction occurred. In addition, the width of the wake of surfactant solutions decreases compared with that of tap water, and the Ka´rma´n vortex street is not found. These effects seem to be due to the elasticity caused by the micellar network in surfactant solution.

Drag Reduction in Laminar Flow Between Two Vertical Coaxial Cylinders

1999 ◽  
Vol 121 (3) ◽  
pp. 541-547 ◽  
Author(s):  
Keizo Watanabe ◽  
Takashi Akino
Keyword(s):  
Drag Reduction ◽  
Polymer Solutions ◽  
Flow Behavior ◽  
Acrylic Resin ◽  
Coaxial Cylinder ◽  
Newtonian Fluids ◽  
Basic Material ◽  
Water Repellent ◽  
Coaxial Cylinders ◽  
Moment Coefficient

Laminar drag reduction has been shown for the flow of a Newtonian fluid in the space between two vertical coaxial cylinders. Experiments were carried out to measure the torque of a bob with a highly water-repellent wall to clarify the effect of the contact surface of the bob on the flow behavior. The basic material of the highly water-repellent wall is fluorine alkane modified acrylic resin with added hydrophobic silica, and the contact angle of the wall is about 150 degree. The radius rations of the bob were 0.932 and 0.676. Test fluids were Newtonian aqueous solutions of 60, 70, and 80 wt% glycerin and polymer solutions. The maximum drag reduction ratio was about 12% for 80 wt% glycerin solution at a radius ratio of 0.932. The moment coefficient of the coaxial cylinder in Newtonian fluids was analyzed for fluid slip, and it was shown that the analytical results agreed well with the experimental data. For the case of non-Newtonian fluids, the fluid slip velocity of polymer solutions is not proportional to the shear stress and the relationship is approximated by power-law equations.

Drag of a Circular Cylinder in Surfactant Solutions at Intermediate Reynolds Number Range

2003 ◽  
Author(s):  
Satoshi Ogata ◽  
Keizo Watanabe ◽  
Yoshihisa Osano
Keyword(s):  
Reynolds Number ◽  
Circular Cylinder ◽  
Drag Reduction ◽  
Drag Coefficient ◽  
Tap Water ◽  
Surfactant Solution ◽  
Number Range ◽  
Surfactant Solutions ◽  
Cylinder Diameter ◽  
Reynolds Number Range

To clarify the behavior of the drag coefficient of a circular cylinder in the intermediate Reynolds number range, the flow around a circular cylinder in surfactant solutions was investigated experimentally by measurement of the drag in the Reynolds number range of 3 × 102 to 7 × 103. The experiments were performed in a vertical re-circulating water tunnel. The drag coefficient was measured using an apparatus which could measure the drag acting on the circular cylinder directly. Five cylinders of diameter d = 5, 7, 10, 13 and 20 mm were tested, the ratios of length to diameter (l/d) were 12, 24 and 48. The test surfactant solutions were aqueous solutions of Ethoquad O/12 at concentrations of 50, 100 and 200 ppm, and sodium salicylate was added as a counterion. It was clarified that the drag coefficient of the cylinder in surfactant solutions increased comparing that in tap water in the Reynolds number lower approximately 103 < Re < 3 × 103. According to the increase of the Reynolds number, the drag coefficient decreased. When Reynolds number exceeded approximately 103 < Re < 3 × 103, the drag coefficient in surfactant decreased in comparison with that in tap water finally. In other ward, the drag reduction occurred in this Reynolds number range. The maximum drag reduction was about 55% for 200 ppm solution and 20mm diameter at Re ≅ 7 × 103. The value of the drag coefficient in surfactant solutions was dependent on not only (l/d) but also cylinder diameter. The drag coefficient increased with increasing cylinder diameter. The increase in the concentration of surfactant solution emphasized the characteristics of drag reduction and drag increase.

Numerical Simulation of Fluid Slip at a Hydrophobic Surface

Volume 4 ◽  
2004 ◽  
Author(s):  
Takao Fujita ◽  
Keizo Watanabe
Keyword(s):  
Boundary Condition ◽  
Laminar Flow ◽  
Circular Cylinder ◽  
Drag Reduction ◽  
Hydrophobic Surface ◽  
Friction Reduction ◽  
Water Repellent ◽  
Two Dimensional ◽  
Hydrophobic Property ◽  
Flow Past

Laminar drag reduction is achieved by using a hydrophobic surface. In this method, fluid slip is applied at the hydrophobic surface. An initial experiment to clarify for a laminar skin friction reduction was conducted using ducts with a highly water-repellent surface. The surface has a fractal-type structure with many fine grooves. Fluid slip at a hydrophobic surface has been analyzed by applying a new wet boundary condition. In this simulation, an internal flow is assumed to be a two-dimensional laminar flow in a rectangular duct and an external flow is assumed to be a two-dimensional laminar flow past a circular cylinder. The VOF technique has been used as the method for tracking gas-liquid interfaces, and the CSF model has been used as the method for modeling surface tension effects. The wet boundary condition for the hydrophobic property on the surface has been determined from the volume ratio in contact with water near the surface. The model with a stable gas-liquid interface and the experimental results of flow past a circular cylinder at Re = 250 without growing the Karman vortex street are made, and these results show that laminar drag reduction occurring due to fluid slip can be explained in this model.

Flow Characteristics of a Rotating Disk in Surfactant Solutions

2000 ◽  
Author(s):  
Satoshi Ogata ◽  
Keizo Watanabe
Keyword(s):  
Boundary Layer ◽  
Tap Water ◽  
Flow Direction ◽  
Flow Behavior ◽  
Flow Characteristics ◽  
Rotating Disk ◽  
Circular Pipe ◽  
Number Range ◽  
Surfactant Solutions ◽  
Momentum Integral

Abstract Recently, considerable interest has developed in surfactant additives for use in district heating and cooling systems to lower the pumping energy requirement. Many studies in the case of surfactant solutions have been done for the flow behavior in a circular pipe. However, few studies have been conducted on flow near a rotating disk in surfactant solutions. In this paper, the flow characteristics near an enclosed rotating disk in surfactant solutions were studied by applying flow visualization techniques and analyzed by applying the momentum integral equations which are related to the three boundary layer problem. The test surfactant solution was Ethoquad 0/12 with sodium salicylate at a concentration of 200ppm and a temperature of 18°C. The flow patterns were obtained at Re = 2.5×105 and 3.5×105 so that the Reynolds number range corresponds with the transition region to turbulent flow in the boundary layer on the rotating disk for Newtonian fluids. Consequently, it has been clarified that the amplitude of the circular vortex on the rotating disk was reduced and the flow direction near the disk was turned outward to the circumferential direction comparing with that of tap water. In additional, the limiting maximum drag reduction asymptote for a moment coefficient of a rotating disk was obtained by applying the momentum integral equation for drag-reducing solutions based on previous papers on circular pipe flow.

CFD Modelling and Validation of Newtonian and Non-Newtonian Fluids in Curved Conduits

2015 ◽  
Vol 786 ◽  
pp. 181-187
Author(s):  
Abdulrahman Yousif ◽  
Azuraien Japper-Jaafar
Keyword(s):  
Pressure Drop ◽  
Drag Reduction ◽  
Reynolds Stress ◽  
Tap Water ◽  
Newtonian Fluids ◽  
Experimental Results ◽  
Polymer Additives ◽  
Centrifugal Forces ◽  
Cfd Modelling

CFD modelling of drag reduction agents (also called Flow Improvers) polymer additives dissolved in a newtonian solvent (UTP tap Water) was carried out in a curved conduit, A 7 equation Reynolds stress set of equations was used to simulate this flow. The purpose of this simulation is validate experimental results that show unusual pressure drop behaviour. CFD experiments show that there is pressure build-up near the end of the curved conduit due to severe centrifugal forces produced by the fluid, confirming the validity of the experimental results.

Correlation of Drag Reduction With Modified Deborah Number For Dilute Polymer Solutions

1967 ◽  
Vol 7 (03) ◽  
pp. 325-332 ◽  
Author(s):  
J.M. Rodriguez ◽  
J.L. Zakin ◽  
G.K. Patterson
Keyword(s):  
Molecular Weight ◽  
Pressure Drop ◽  
Drag Reduction ◽  
Friction Factor ◽  
High Molecular Weight ◽  
Polymer Solutions ◽  
Petroleum Industry ◽  
Nonpolar Solvents ◽  
Factor Ratio ◽  
Drag Ratio

Abstract Correlation has been obtained between drag-reducing characteristics forturbulent flow in a pipe and measurable properties of several polymersolutions. Several concentrations of high molecular weight polymethylmethacrylate in toluene, high molecular weight polyisobutylene in both tolueneand cyclohexane, medium molecular weight polyisobutylene in cyclohexane andbenzene and low molecular weight polystyrene in toluene were studied. Dataobtained in these nonpolar solvents and literature data for more polar solventswere successfully correlated as the ratio of measured friction factor to purelyviscous friction factor vs the modified Deborah numbervr1/D0.2, where r1 is the first-moderelaxation time of the solution estimated by the Zimm theory. A shift factorwhich is a function of intrinsic viscosity 1/(4[?] - 1) allowed all the dataobtained with nonpolar solvents to be correlated as a single function. Forthese systems, most of the data fit a single curve to within ±5 percent of theaverage friction factor ratio. The shift factor did not give a unique functionof the data for the more polar systems. INTRODUCTION The phenomenon of drag reduction in polymer solutions was first studied byToms1 in dilute solutions of polymethyl methacrylate inmonochlorobenzene. The drag ratio for flow through circular tubes has beendefined2 as the ratio of the pressure - drop of the solution to thepressure drop of the solvent at the same flow rate. The drag ratio is less than1.0 for a drag-reducing fluid. Practical use of drag reduction is being made infracturing operations in the petroleum industry.3 A more fundamental quantity is the friction factor ratio, defined as theratio of the observed pressure drop to that predicted for a solution of thesame viscosity characteristics and density at equal flow rates using theDodge-Metzner friction factor equation.4Equation 1 Viscous solutions with drag ratios greater than 1.0 can have friction factorratios less than 1.0. For practical applications, it is drag reduction which isof interest. However, for correlation the fundamental ratio is the frictionfactor ratio. In recent years, drag reduction has been studied extensively. Recent studieshave shown that reasonable predictions of the incipience of drag reduction inpolymer solutions can be made from the properties of the solutions and the flowvariables.5 However, it has not been possible to predict accuratelythe amount of drag reduction to be expected for a given polymer solutionwithout any drag-reducing turbulent flow data on the samesolution.6

Formation Process of Taylor Cells of a Surfactant Solution

2002 ◽  
Author(s):  
Keizo Watanabe ◽  
Tsukasa Takayama ◽  
Satoshi Ogata
Keyword(s):  
Formation Process ◽  
Tap Water ◽  
Surfactant Solution ◽  
Cylinder Wall ◽  
Number Range ◽  
Taylor Vortices ◽  
Surfactant Solutions ◽  
Flow Test ◽  
Stabilizing Effect ◽  
Shear Induced Structure

The flow of surfactant solutions between two coaxial cylinders was investigated using the laser-induced-fluorescence flow visualization technique to clarify the effect of drag-reducing additives on the formation process of Taylor cells in Taylor-Couette flow. Test fluids were Ethoquad O/12 10, 50 and 100 ppm surfactant solutions. In the Taylor number range of, 1.2×105 ≤ Ta ≤ 7.1×105, tap water and 10 ppm surfactant solution flows consisted of Taylor vortices and much smaller Go¨rtler vortices at the rotating inner cylinder wall. However, in 50 and 100 ppm surfactant solutions, Taylor vortices are not apparent and Go¨rtler vortices are collapsed. Measurement of the wavelength of Go¨rtler vortices led to the conclusion that surfactant solutions have a stabilizing effect on Go¨rtler instabilities. This effect depends on the concentration of surfactant solutions, and becomes considerable with increasing acceleration of the rotating inner cylinder. By considering the experimental results for the surfactant solutions without counterions, in which Taylor cells were not formed, it was shown that the increase in the local field viscosity based on the shear-induced structure of the surfactant solutions has a stabilizing effect on Go¨rtler instability.

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