Droplets in an axisymmetric microtube: Effects of aspect ratio and fluid interfaces

DeVoria, Adam C.; Mohseni, Kamran

doi:10.1063/1.4904753

Cited by 11 publications

(4 citation statements)

References 44 publications

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“…PIV has proved to be more effective in the visualization of the flow field structures of a fluid droplet (Horton et al, 1965;DeVoria and Mohseni, 2015). The PIV technique has been used to visualize the internal flow fields of a fluid droplet, for example in the representation of instantaneous velocities of each particle with a vector field shown in our previous work (Gatete et al, 2023).…”

Section: Improvement Of the Accuracy Of Piv Measurement Of Flow Field...mentioning

confidence: 99%

Improvement of the accuracy of PIV measurement of flow field in a levitated droplet

GATETE,

SHEN,

KANEKO

2024

Mechanical Engineering Journal

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The use of levitated droplets with electrostatic and ultrasonic fields has attracted much attention in the fields of materials development, chemical engineering, droplet-based microfluidics, inkjet printing, and aerospace engineering. To use them properly, it is essential to understand the internal flow of the suspended droplet. The flow inside fluid droplets is visualized with the particle image velocimetry (PIV) method. The fluid that is to be investigated is scattered with small particles that follow the flow well. One problem that occurs when the PIV method is used to measure velocity fields inside droplets is however that light refracts at the droplet surface and the internal flow curvature is distorted. The aim of this research is to improve the accuracy of PIV measurement by correcting the distorted particle images of an acoustically levitated droplet using calibration method. In this study, a simulated droplet with different refractive index and aspect ratio was used to investigate their influence on distortion correction. The circular target plate was also utilized to correct the distortion in a simulated droplet using a calibration method of the python-OpenCV. The experimental results showed that the internal flow curvature can be distorted in two types such as barrel, pincushion distortions, and increase as the refractive index increases. Therefore, correction of the distorted image of particles in the droplet showed good convergence as the aspect ratio decreased.

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Section: Improvement Of the Accuracy Of Piv Measurement Of Flow Field...mentioning

confidence: 99%

Improvement of the accuracy of PIV measurement of flow field in a levitated droplet

GATETE,

SHEN,

KANEKO

2024

Mechanical Engineering Journal

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“…Due to the limitations of experimental conditions, there are only two parameters of inner-diameter, and the amount of data is small, which is not enough for fitting and regression. After the nanoparticles are added, the thermal resistance of the heat pipe at low heating power input is significantly reduced, but the addition of nanoparticles increases the viscosity of the working fluid, thereby increasing the flow resistance [19]. Therefore, the excessively large concentration of nanoparticles causes a decrease in heat transfer performance of the pulsating heat pipe.…”

Section: Input and Output Parametersmentioning

confidence: 99%

Testing algorithm for heat transfer performance of nanofluid-filled heat pipe based on neural network

Lei

2020

Open Physics

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Traditional testing algorithm based on pattern matching is impossible to effectively analyze the heat transfer performance of heat pipes filled with different concentrations of nanofluids, so the testing algorithm for heat transfer performance of a nanofluidic heat pipe based on neural network is proposed. Nanofluids are obtained by weighing, preparing, stirring, standing and shaking using dichotomy. Based on this, the heat transfer performance analysis model of the nanofluidic heat pipe based on artificial neural network is constructed, which is applied to the analysis of heat transfer performance of nanofluidic heat pipes to achieve accurate analysis. The experimental results show that the proposed algorithm can effectively analyze the heat transfer performance of heat pipes under different concentrations of nanofluids, and the heat transfer performance of heat pipes is best when the volume fraction of nanofluids is 0.15%.

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“…Numerous experimental studies have been conducted on the flow and thermal characteristics of Taylor flow in circular and square channels in terms of Taylor bubble shapes [1][2], bubble velocities [3], slug lengths [1,4], liquid film thickness [5][6], flow fields [7][8], pressure drops [9][10], and heat transfer characteristics [1,[11][12][13][14]. Exhaustive reviews about these have been performed by Angeli and Gavriilidis [15], Gupta et al [16], Eain et al [17], and Bandara et al [18].…”

mentioning

confidence: 99%

“…A recirculating flow, which could efficiently enhance the heat and mass transfer in the continuous phase, is induced by two-phase interfaces. The visualization of this recirculating flow has been conducted by Devoria et al [7] and Meyer et al [8] using micro-PIV technology. The pressure drop also increases with the addition of a second incompressible phase.…”

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confidence: 99%

Heat transfer and pressure drop characteristics of gas–liquid Taylor flow in mini ducts of square and rectangular cross-sections

Zhang

Fletcher

2016

International Journal of Heat and Mass Transfer

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The thermal and flow characteristics of gas-liquid Taylor flow in vertical mini square and rectangular ducts were studied numerically for water and ethylene glycol as the liquid phase and nitrogen as the gas phase. The effects of fluid properties, flow parameters, and aspect ratio on the bubble shape, recirculation time, friction factor, and Nusselt number are discussed. The results indicate that the gas phase is confined by the tube wall in square and rectangular tubes leading to an asymmetrical Taylor bubble at low Capillary numbers, while an axisymmetric bubble is formed at high Capillary numbers. The liquid film thicknesses in the square and rectangular ducts are not uniform with a thicker liquid film formed at the tube corner. The recirculation region decreases and the dimensionless recirculation time increases with increasing Capillary number, which means that the intensity of recirculation decreases with increasing Capillary number. The friction factor decreases with increasing two-phase mixing velocity and aspect ratio and increases in gas void fraction, while the reverse is true for the two-phase Nusselt number. Compared with the ethylene glycol/nitrogen cases, the addition of Taylor bubble plays a more significant role on the pressure drop increase and heat transfer enhancement for the water/nitrogen cases because of the larger recirculation volume and smaller dimensionless recirculation time. Two empirical correlations are developed to predict the apparent slug Nusselt number and the film-to-slug Nusselt number for gas-liquid Taylor flow in square and rectangular ducts.

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Droplets in an axisymmetric microtube: Effects of aspect ratio and fluid interfaces

Cited by 11 publications

References 44 publications

Improvement of the accuracy of PIV measurement of flow field in a levitated droplet

Improvement of the accuracy of PIV measurement of flow field in a levitated droplet

Testing algorithm for heat transfer performance of nanofluid-filled heat pipe based on neural network

Heat transfer and pressure drop characteristics of gas–liquid Taylor flow in mini ducts of square and rectangular cross-sections

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