Experimental and neural network modelling of polymer drag reduction in 180° bends

Ayegba, Paul Onubi; Edomwonyi‐Otu, Lawrence C.; Yusuf, Nurudeen; Abubakar, Abdulkareem

doi:10.1016/j.rinma.2019.100012

Cited by 7 publications

(12 citation statements)

References 31 publications

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“…The contribution of secondary flows to pressure gradient, relative to wall and interface shear stresses, is significant at moderate flowrates in turbulent flow regime. In single phase flow, when secondary flow contribution is significant, the pressure gradient in bends is markedly higher than that in straight pipes of comparable length [18,19]. The difference generally increases with curvature ratio and decreases with the length of the bend.…”

Section: Introductionmentioning

confidence: 95%

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Flow pattern and pressure drop for oil–water flows in and around 180° bends

et al. 2021

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Pressure drop and flow pattern of oil–water flows were investigated in a 19-mm ID clear polyvinyl chloride pipe consisting of U-bend with radius of curvature of 100 mm. The range for oil and water superficial velocities tested was $$0.04 \le U_{{{\text{so}}}} \le 0.950 \;{\text{m/s}}$$ 0.04 ≤ U so ≤ 0.950 m/s and $$0.13 \le U_{{{\text{sw}}}} \le 1.10 \;{\text{m/s}}$$ 0.13 ≤ U sw ≤ 1.10 m/s , respectively. Measurements were carried out under different flow conditions in a test section that consisted of four different parts: upstream of the bend, at the bend and at two redeveloping flow locations after the bend. The result indicated that the bend had limited influence on downstream flow patterns. However, the shear forces imposed by the bend caused some shift flow pattern transition and bubble characteristics in the redeveloping flow section after the bend relative to develop flow before the bend. Generally, pressure gradient at all the test sections increased with both oil fraction and water superficial velocity and there was a sharp change of pressure gradient profile during phase inversion. The transition point where phase inversion occurred was always within the range of $$0.4 \le U_{{{\text{sw}}}} \le 0.54 \;{\text{m/s}}$$ 0.4 ≤ U sw ≤ 0.54 m/s . Pressure losses differed at the various test sections, and the difference was strongly linked to the superficial velocity of the phases and the flow pattern. At high mixture velocity, pressure losses at the redeveloping section after the bend were higher than that at the bend and that for fully developed flows. At low mixture velocity, pressure losses at the bend are higher than in the straight sections. Pressure drop generally decreased with level of flow development downstream of the bend.

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Section: Introductionmentioning

confidence: 95%

“…The behaviour of the fluid flow in bends is complex due to the action of centrifugal forces on the mixture along with the underdeveloped flow profile in bends [17][18][19]. Wall and interfacial frictions in oil-water two flows contribute the most to pressure gradient in developed flows in straight horizontal smooth pipes [20][21][22][23].…”

Section: Introductionmentioning

confidence: 99%

Flow pattern and pressure drop for oil–water flows in and around 180° bends

et al. 2021

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“…Applications of PIV technique for the capture of vortex structures are limited in open literature. Considering the significant effect of DRAs on vortical structures there is need for future PIV investigation to focus on the interaction these additives have with vortices at various Reynolds and Weissenberg numbers. A recent study on DR in bend was carried out by Ayegba et al A number of interesting characteristics of drag-reducing solution flows was reported in bends. These include; lower DR in the bend relative to fully developed flows in horizontal straight pipes; lower DR in the redeveloping straight pipe section downstream of the bend.…”

Section: Research Gapsmentioning

confidence: 99%

“…8. A recent study on DR in bend was carried out by Ayegba et al 127 A number of interesting characteristics of drag-reducing solution flows was reported in bends. These include; lower DR in the bend relative to fully developed flows in horizontal straight pipes; lower DR in the redeveloping straight pipe section downstream of the bend.…”

Section: Recent Numerical Simulation Studies Have Revealed Important mentioning

confidence: 99%

Turbulence statistics and flow structure in fluid flow using particle image velocimetry technique: A review

Ayegba

Edomwonyi‐Otu

2020

Engineering Reports

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Particle image velocimetry (PIV) measurement technique provides an excellent opportunity for investigating instantaneous spatial structures which are not always possible with point measurements techniques like laser Doppler velocimetry. In this review, it was shown that PIV technique provides an effective means of visualizing important structures of Newtonian and drag‐reducing fluid flows. Such structures include large‐scale‐events that constitute an important portion of the Reynolds stress tensor; shear layers of drag‐reducing flows, which have been suggested to constitute the mechanism of drag reduction (DR); and near wall vortices/low speed streaks which constitute the mechanism of turbulence production. PIV investigations of turbulence statistics in Newtonian and drag‐reducing fluid flows were reviewed with the view of providing explanation to DR by additives. Results of turbulence statistics, for Newtonian fluid flow, showed that streamwise velocity fluctuations and turbulence intensity had peak values close to the wall, in a region of high mean velocity gradient, while radial fluctuating velocity and Reynolds stress tensor had peaks further from the wall and at approximately the same detachment from the wall. In single‐ and two‐phase flows in horizontal channels, the velocity profile of polymer solution, in the turbulent regime, show asymmetric behavior. This review highlighted important interfacial characteristics in gas‐liquid flows such as S‐shaped velocity profile as well as the turbulences statistics in each phase and across the interface region. Drag‐reducing agents (DRAs)‐imposed changes on turbulence statistics and flow structures were also examined. PIV studies of drag‐reducing flows showed that DRAs act to dampen wall‐normal‐, streamwise fluctuating velocity, and Reynolds stress tensor. The reduction in Reynolds stress tensor is higher than the reduction of both wall‐normal and streamwise velocity fluctuations and this discrepancy has been associated with the decorrelation of the component of fluctuating velocity. Furthermore, the addition of DRA produces a shift of the peak of wall‐normal velocity fluctuations further from the wall due to increased buffer layer thickness. DRAs do not only act to reduce drag but also to modify the flow structure. The major influence of DRAs on flow structures is seen in the reduced strength and population of vortices close to the wall, increased spacing between low‐speed streaks, reduced frequency of large‐scale events and reduced concentration of small eddies. Effect of DRAs on flow structures depends not only on the level of DR but also on the concentration and molecular weight. The effect of concentration is linked to the elastic properties of the DRA. The influence of DRA on oil‐water flows in similar to its effect on single phase water flow with regards to changes in near wall structures and turbulence statistics. A few research gaps and limitations of the PIV techniques were also highlighted.

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“…The behavior of the fluid flow in bends is complex due to the action of centrifugal forces on the mixture along with the under-developed flow profile in bends [12]- [14]. Wall and interfacial frictions in oil-water two flows contribute the most to pressure gradient in developed flows in straight horizontal smooth pipes [15]- [18].…”

Section: Introductionmentioning

confidence: 99%

Flow Pattern and Pressure Drop for Oil-Water Flows in and around 180° Bends

Ayegba

Edomwonyi‐Otu

Abubakar

et al. 2020

Preprint

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Pressure drop and flow pattern of oil-water flows were investigated in a 19 mm ID clear polyvinyl chloride pipe consisting of U-bend with radius of curvature of 100 mm. The range for oil and water superficial velocities tested were and respectively. Measurements were carried out under different flow conditions in a test section that consisted of four different parts: upstream of the bend, at the bend and at two redeveloping flow locations after the bend. The result indicated that the bend had limited influence on downstream flow patterns. However, the shear forces imposed by the bend caused some shift flow pattern transition and bubble characteristics in the redeveloping flow section after the bend relative to develop flow before the bend. Generally, pressure gradient at all the test sections increased with both oil fraction and water superficial velocity and there was a sharp change of pressure gradient profile during phase inversion. The transition point where phase inversion occurred was always within the range of . Pressure losses differed at the various test sections and the difference was strongly linked to the superficial velocity of the phases and the flow pattern. At high mixture velocity, pressure losses at the redeveloping section after the bend were higher than that at the bend and that for fully developed flows. At low mixture velocity, pressure losses at the bend are higher than in the straight sections. Pressure drop generally decreased with level of flow development downstream of the bend.

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Experimental and neural network modelling of polymer drag reduction in 180° bends

Cited by 7 publications

References 31 publications

Flow pattern and pressure drop for oil–water flows in and around 180° bends

Flow pattern and pressure drop for oil–water flows in and around 180° bends

Turbulence statistics and flow structure in fluid flow using particle image velocimetry technique: A review

Flow Pattern and Pressure Drop for Oil-Water Flows in and around 180° Bends

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Experimental and neural network modelling of polymer drag reduction in 180° bends

Cited by 7 publications

References 31 publications

Flow pattern and pressure drop for oil–water flows in and around 180° bends

Flow pattern and pressure drop for oil–water flows in and around 180° bends

Turbulence statistics and flow structure in fluid flow using particle image velocimetry technique: A review

Flow Pattern and Pressure Drop for Oil-Water Flows in and around 180&deg; Bends

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Flow Pattern and Pressure Drop for Oil-Water Flows in and around 180° Bends