Transition of plug to slug flow and associated fluid dynamics

Thaker, Jignesh; Banerjee, Jyotirmay

doi:10.1016/j.ijmultiphaseflow.2017.01.014

Cited by 44 publications

(10 citation statements)

References 21 publications

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“…Slug flow (or Taylor flow) is defined as the successive displacement of a total slug unit composed of an air bubble and a liquid phase known as liquid slug. 76 The Movie SI 1 (Supplementary Information) presents the typical results from microscopy in the experiments. The green fluorescence represents the liquid interface, while zerofluorescent channels represent the gas bubbles.…”

Section: Resultsmentioning

confidence: 99%

In Vitro Investigation of Gas Embolism in Microfluidic Networks Mimicking Microvasculature

Mardanpour¹,

Perumal²,

Mahmoodi³

et al. 2022

Preprint

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Gas embolism is a medical condition leading to the blockage of blood flow in the microvasculature by gas bubbles. While reported as rare, gas embolism often has devastating, fatal physiological consequences. Despite this acute importance, the genesis and evolution of air bubbles in blood vessels under different physiological conditions, such as blood viscosity and blood flow rate, is still understudied, largely because of difficult experimentation and in situ visualization. The objective of this work was to study the gas embolism phenomenon in vitro, using a microfluidic system that mimicked the architecture of microvasculature. The microfluidic systems comprised linear channels with two different air inlet types, namely, T- and Y-junctions with three different widths (20 µm, 40 µm, and 60 µm), and a 30 µm width honeycombed network with three bifurcation angles (30°, 60°, and 90°). Three synthetic liquids equivalent to 0%, 20%, and 46% hematocrit that mimicked the physiological blood viscosity and hematocrit concentrations were used. Our results show that: (i) 20 µm and 40 µm width channels had an elevated risk of gas embolism due to wide fluctuations in the total slug sizes; (ii) the resistance to the flow of air bubbles increased with the increase in the equivalent concentration of hematocrit; (iii) gas bubbles causing blockages and dampening of the flow velocity were frequently observed in 20 µm channels, and lastly (iv) increased risk of gas embolism was observed in the honeycomb architecture with 60° and 30° bifurcations. This work suggests that in vitro experimentation using microfluidic devices with microvascular tissue-like structures opens the possibility of studying this medical condition with high reproducibility and impacts the fact-based medical guidelines for preventing or mitigating iatrogenic occurrences.

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Section: Resultsmentioning

confidence: 99%

In Vitro Investigation of Gas Embolism in Microfluidic Networks Mimicking Microvasculature

Mardanpour¹,

Perumal²,

Mahmoodi³

et al. 2022

Preprint

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“…These characteristics are typical of a slug flow. Thaker and Banerjee [38] explained that an increase in the superficial velocity of the gas leads to an increase in the relative velocity between the liquid slugs and the liquid film supporting the gas pocket. Consequently, the shear stress at the slug body/gas bubble tail interface is increased and the bubbles entrainment overcomes the surface tension.…”

Section: Visual Observationsmentioning

confidence: 99%

Onset of intermittent flow: Visualization of flow structures

Arabi

Salhi

Bouderbal

et al. 2021

Oil Gas Sci. Technol. – Rev. IFP Energies nouvelles

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The transition from stratified to intermittent air-water two-phase flow was investigated experimentally, by flow visualization and pressure drop signals analyses, in a 30 mm ID pipe. The intermittent flow’s onset was found to be mainly dependent on the liquid superficial velocity and the pipe diameter. Plug flow, Less Aerated Slug (LAS) or Highly Aerated Slug (HAS) flows could be obtained on the gas superficial velocity grounds. The available models, compared to experiments, could not predict adequately the intermittent flow onset. The appearance of liquid slugs was revealed by peaks in the pressure drop signal. Furthermore, it was shown that the available slug frequency correlations were not valid in the zone of the onset of intermittent flow.

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“…According to Barnea (1987) and Thaker and Banerjee (2017), the plug flow is generally known as an elongated bubble flow without the appearance of dispersed bubbles. For all conditions of G ≤ 760 kg/(m 2 s) with q" TS = 1 kW/m 2 and G = 890 kg/(m 2 s) with q" TS = 5 kW/m 2 , plug flow was predominant with vapor plugs approximately the diameter of the tube.…”

Section: Plug Flowmentioning

confidence: 99%

“…The increase of vapor quality and, consequently, of void fraction provided plug coalescence along the flow, resulting in the formation of slugs. According to Thaker and Banerjee (2017), slug flow is characterized by intermittent appearance of aerated liquid slugs separated from one another by elongated slug bubble. Typical examples of slug flow are shown in Fig.…”

Section: Slug Flowmentioning

confidence: 99%