The distribution of fluids in irregular capillary tubes: a new capillary model based on the single-corner capillary

Long, Long; Zhang, Bing

doi:10.1007/s13202-017-0385-4

Cited by 7 publications

(13 citation statements)

References 38 publications

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“…The oil in the triangular crosssectional capillary is the first to be separated, the square cross section is the second, and the regular pentagonal cross section is the last. According to previous research [33] and the results of the current study (Figure 4), when the number of sides of a cross section increases, and the high-order polygon gradually approaches a circle, the saturation of the water phase decreases. Otherwise, the saturation of the water phase increases, and the water channels become larger.…”

Section: Pressure Drop In Different Capillariessupporting

confidence: 83%

A Numerical Study of Initiation and Migration of Trapped Oil in Capillaries with Noncircular Cross Sections

Long

Gong

et al. 2019

Geofluids

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To clarify the initiation and migration mechanisms of a discontinuous oil phase in pores, a numerical study was performed to interpret the starting phenomenon and flowing rules of oil trapped in capillaries that have noncircular cross sections. In this study, capillaries with three different cross sections were used to investigate the deformation law of oil and the pressure drop across these microchannels at different displacement velocities by computational fluid dynamics (CFD). The geometrical structure of the microchannels was precisely controlled, and the migration process of the oil, which is too small to be observed by direct experimentation, was assessed and quantitatively analyzed. By analyzing the shape of the trapped oil after reaching a steady state at different velocities, the nonstart and start conditions could be distinguished and the accuracy of the numerical method was verified by a comparison with an analytical method (the MS-P method). Two aspects of oil migration in noncircular microchannels were observed in combination with previous studies: there is a driving force on the cross section of the oil drop and a viscous force at the oil-water interface in the corners, and the more irregular the pore section is, the more easily the trapped oil will migrate. Additionally, the influence of the microchannel cross-sectional shape on the non-Darcy flow of a discontinuous oil phase was clarified. It can be concluded that the presence of the non-Darcy flow in pores arises because trapped oil, as a discontinuous phase, cannot be separated from the capillary wall without reaching critical velocity.

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Section: Pressure Drop In Different Capillariessupporting

confidence: 83%

A Numerical Study of Initiation and Migration of Trapped Oil in Capillaries with Noncircular Cross Sections

Long

Gong

et al. 2019

Geofluids

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“…They also concluded that there exists a capillary flow limit. Other notable works on capillary-driven flow in open grooves can be found in [7][8][9][10][11][12][13] . More recently, attention has been given to surface properties and its effect on capillary rise.…”

Section: List Of Symbolsmentioning

confidence: 99%

A general form of capillary rise equation in micro-grooves

Abadi

Bahrami

2020

Sci Rep

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Micro-grooves are a crucial feature in many applications, such as microelectro-mechanical systems, drug delivery, heat pipes, sorption systems, and microfluidic devices. Micro-grooves utilize capillary action to deliver a liquid, with no need for an extra pumping device, which makes them unique and desirable for numerous systems. Although the capillary action is well studied, all the available equations for the capillary rise are case-specific and depend on the geometry of the groove, surface properties, and the transport liquid. In this study, a unified non-dimensional model for capillary rise is proposed that can accurately predict the capillary rise for any given groove geometry and condition and only depends on two parameters: contact angle and characteristic length scale, defined as the ratio of the liquid–vapor to the solid–liquid interface. The proposed model is compared against data from the literature and can capture the experimental results with less than 10% relative difference. The effect of the grooves’ height, width, and contact angle is investigated and reported. This study can be used for a unified approach in designing heat pipes, capillary-assisted evaporators for sorption systems, drug delivery micro-fluidic devices, etc.

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“… 31 They introduced a dimensionless shape factor ( G ) based on the perimeter and area of the cross-section and determined the equivalent shape factors for various geometries. 17 , 31 Ponomarenko et al (2011) derived a general law for the capillary rise of wetting liquids in the corner of various geometries. 32 …”

Section: Introductionmentioning

confidence: 99%

“… 36 Long and Zhang (2017) analyzed the distribution of fluids and interface curvature based on single-corner capillary model in irregular capillary tubes. 31 …”

Section: Introductionmentioning

confidence: 99%

“… 30 , 37 − 43 The critical contact angle for the n -sided polygonal tube reaches zero, becoming similar to a circular tube shape as “ n ” approaches infinity, and the corner menisci will be vanished. 31 The rivulet rise in the corners and the increase in the corner menisci radius due to the increasing side number in regular capillary tubes are schematically shown in Figure 1 .…”

Section: Introductionmentioning

confidence: 99%

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Modeling Approach to Determine Static Rivulet Height in Regular Polygonal Capillary Tubes

et al. 2022

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The rise of partially wetting liquids along the corners of noncircular capillary tubes is observed in many practical science and engineering applications such as wastewater treatment using membranes, remediation, oil recovery from petroleum reservoirs, and blood flow. In this paper, rivulet rise at the corners of polygonal capillary tubes is studied for partially wetting liquids with contact angles below the critical value. The presence of corners changes the distribution of a liquid in an incomplete wetting condition. In this study, geometrical models are proposed to better understand the capillary rise and flow behavior at the corners. A geometrical solution for the capillary rivulet height and profile is derived under gravity in triangular, square, and pentagonal capillary tubes. The effects of several factors including contact angle, number of polygon sides, and liquid properties on the capillary rivulet height are examined. It was found that the ratio of liquid surface tension to density directly affects the corner rise, while it has an inverse relationship with other factors. The maximum rivulet height of 91.6 mm is obtained in the triangular capillary tube with a side length of 1 mm and a contact angle of 30° for polydimethylsiloxane (PDMS-20)-air fluid pair. The minimum capillary rivulet height of 6.2 mm, on the other hand, is achieved in the pentagonal capillary tube, with a side length of 3 mm and a contact angle of 30°. To validate the developed analytical approach, comparisons are made between the model results, literature predictions, and experimental data. In addition, the geometrical model for a square capillary tube is compared with previous published studies, revealing a good agreement. This study provides quantitative results for the influence of capillary tube shape on the flow behavior of fluids in noncircular tubes that can be useful for control and optimization of transport phenomena in corresponding systems.

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The distribution of fluids in irregular capillary tubes: a new capillary model based on the single-corner capillary

Cited by 7 publications

References 38 publications

A Numerical Study of Initiation and Migration of Trapped Oil in Capillaries with Noncircular Cross Sections

A Numerical Study of Initiation and Migration of Trapped Oil in Capillaries with Noncircular Cross Sections

A general form of capillary rise equation in micro-grooves

Modeling Approach to Determine Static Rivulet Height in Regular Polygonal Capillary Tubes

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