An exponential decay function for polymer degradation in turbulent drag reduction

Choi, Hyoung Jin; Kim, Chul A.; Sohn, Jeong‐In; Jhon, Myung S.

doi:10.1016/s0141-3910(00)00080-x

Cited by 67 publications

(34 citation statements)

References 21 publications

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“…A larger value of h indicates fast degradation, while a larger value of W implies a low shear stability. Such as PEO and PAAM with 2.5 ppm is possess larger values of h and W, i.e., possess fast degradation and low shear stability [18,19]. And observed from Table 2.…”

Section: Resultsmentioning

confidence: 78%

Rotating disk apparatus for polymer-induced turbulent drag reduction

Hong

Choi

Kim³

2008

J Mech Sci Technol

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In order to investigate turbulent drag reduction (DR), a rotating disk apparatus (RDA) generating an "external flow" was designed and then polymer-induced DR efficiency of water-soluble polymers both poly (ethylene oxide) (PEO) and poly (acryl amide) (PAAM) were examined as a function of either polymer concentration or temperature. The need for a sensitive measuring system at high Reynolds numbers has stimulated the development of a high-precision computer-aided system, which is able to measure the difference between the torques for a Newtonian fluid and a dilute polymeric solution with drag reducers very accurately. Their mechanical degradation behavior in the RDA as a function of time in a turbulent flow was also analyzed using both a simple exponential decay function and a fractional exponential decay equation. The fractional exponential decay equation was found to fit the experimental data better than the simple first-order degradation exponential decay function in the case of PEO.

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Section: Resultsmentioning

confidence: 78%

Rotating disk apparatus for polymer-induced turbulent drag reduction

Hong

Choi

Kim³

2008

J Mech Sci Technol

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“…Until now, some researches [60,[64][65][66][67][68][69] have indicated that polymer molecular weight, molecular weight distribution, temperature, solvent solubility, polymer concentration, turbulent intensity, preparation and storage methods, entrance or end effects, and flow geometry may influence polymer degradation in turbulent flows. Nevertheless, it is noteworthy that due to various experimental conditions some conflicting results still exist when explaining degradation with the above factors.…”

Section: Effects Of Polymer Degradationmentioning

confidence: 99%

“…Choi et al [68] investigated the applicability of one empirical exponential decay function, which is proposed by Bello et al [70] for the polymer degradation in a dragreduced turbulent pipe flow. The results showed that the single exponential decay model is not universally suitable for all polymeric drag reducers.…”

Section: Effects Of Polymer Degradationmentioning

confidence: 99%

“…The method of preparing polymer solutions needs optimization and same preparation procedures should be taken to compare the results of different DRs fairly [72]. The rotating disk apparatus can be utilized to investigate basic problems for external flow in laboratory studies [67,68]. Furthermore, the polymer degradation should be incorporated into the theoretical model of drag reduction for the drag-reduced flow with inhomogeneous polymer solutions in future.…”

Section: Effects Of Polymer Degradationmentioning

confidence: 99%

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A Short Review on Drag-Reduced Turbulent Flow of Inhomogeneous Polymer Solutions

Kawaguchi

2013

Advances in Mechanical Engineering

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Turbulent drag reduction by additives is an effective approach to save energy in wall turbulence. Improvement of this approach requires a better understanding of the interactions between turbulence and additives including the complex changes in turbulence under various conditions of additives. In this paper we review some recent progress in the investigations of drag reduction in wall turbulence with inhomogeneous polymer solutions via slot-injection and wall-blowing methods. The turbulent statistics characteristics and coherent structures modified by the inhomogeneous polymer additives and the polymer diffusion characteristics in the turbulent boundary layer (TBL) flow and channel flow are discussed in terms of previous experimental and numerical studies. This review also presents a discussion of current limitations and future directions in these areas. Readers may find it helpful in understanding the phenomenon of turbulent drag reduction by inhomogeneous polymer additives and in developing practical applications.

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“…Among these polymers are polyethylene oxide (PEO) [3][4][5][6][7], polyacrylamide (PAAM) [8][9][10], polyisobutylene (PIB) [11][12][13][14], xanthan gum [15][16][17], and guar gum [18,19], among others. However, most of these polymers in the solution are often influenced by mechanical degradation, which reduces their short-term DR effectiveness [19,20]. Other materials that have the capability to withstand mechanical degradation by the formation of micelles have been explored as well.…”

Section: Introductionmentioning

confidence: 99%

Enhancing the Drag Reduction Phenomenon within a Rotating Disk Apparatus Using Polymer-Surfactant Additives

et al. 2016

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Pipelines and tubes play important roles in transporting economic liquids, such as water, petroleum derivatives, and crude oil. However, turbulence reduces the initial flow rate at which liquids are pumped, thereby making liquid transportation through pipelines inefficient. This study focuses on enhancing the drag reduction (DR) phenomenon within a rotating disk apparatus (RDA) using polymer-surfactant additives. The complex mixture of polyisobutylene (PIB) and sodium dioctyl sulfosuccinate (SDS) was used. These materials were tested individually and as a complex mixture in RDA at various concentrations and rotational speeds (rpm). The morphology of this complex was investigated using transmission electronic microscopy (TEM). The reduction of the degradation level caused by the continuous circulation of surfactant additives in RDA could improve the long-term DR level. Experimental result shows that the maximum %DR of the complex mixture was 21.455% at 3000 rpm, while the PIB and SDS were 19.197% and 8.03%, respectively. Therefore, the complex mixture had better performance than these substances alone and were highly dependent on the alkyl chain of the surfactant.

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An exponential decay function for polymer degradation in turbulent drag reduction

Cited by 67 publications

References 21 publications

Rotating disk apparatus for polymer-induced turbulent drag reduction

Rotating disk apparatus for polymer-induced turbulent drag reduction

A Short Review on Drag-Reduced Turbulent Flow of Inhomogeneous Polymer Solutions

Enhancing the Drag Reduction Phenomenon within a Rotating Disk Apparatus Using Polymer-Surfactant Additives

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