Numerical simulation of the pressure drop and heat transfer of two phase slug flows in microtubes using moving frame of reference technique

Talimi, Vandad; Muzychka, Y. S.; Kocabıyık, Serpil

doi:10.1016/j.ijheatmasstransfer.2012.06.044

Cited by 31 publications

(16 citation statements)

References 39 publications

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“…Various interface tracking/capturing techniques have been employed to simulate the heat transfer in droplets, slugs, and plugs, such as the volume of fluid method [19], the level set method [20,21], and the phase field method [22]. Regarding the geometries of microchannels, most simulations were performed with cylindrical microcapillaries [18,20,22,21,23,19] or two dimensional (2D) microchannels [8], where the three dimensional (3D) effect on the flow and on the heat transfer process cannot be considered. However, in most microchannel heat exchangers, the microchannels usually have rectangular or other non-circular cross sections [14,15,16,17].…”

Section: Introductionmentioning

confidence: 99%

Three dimensional features of convective heat transfer in droplet-based microchannel heat sinks

Che

Wong

Nguyen

et al. 2015

International Journal of Heat and Mass Transfer

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Convective heat transfer in droplet-based microchannel heat sinks can be enhanced by the recirculating vortices due to the presence of interfaces. In rectangular microchannels, the three dimensional structures of the vortices and the 'gutters' (i.e., the space between the curved droplet interface and the corner of the microchannel) can significantly affect the heat transfer process. Numerical simulations of the heat transfer process are performed to study the three dimensional features in droplet-based microchannel heat sinks. The finite volume method and the level set method are employed to simulate the flow dynamics, the evolution of the interface, and the heat transfer. The results show that the 'gutters' can hinder the heat transfer process because of its parallel flow, whereas the recirculating flow in droplets and in slug regions between successive droplets can enhance the heat transfer by advecting hot fluid towards the center of the droplets/slugs and advecting fresh fluid towards the wall of the channel. The effects of the length of droplets, the aspect ratio of the channel cross sections, and the Peclet number are analyzed.

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Section: Introductionmentioning

confidence: 99%

Three dimensional features of convective heat transfer in droplet-based microchannel heat sinks

Che

Wong

Nguyen

et al. 2015

International Journal of Heat and Mass Transfer

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“…The effectiveness of the suppression approach allows the use of non-uniform mesh elements that help to significantly reduce the numerical cost. While this method had been successfully employed for studying two-phase convective heat transfer without evaporation [35] [36], several modifications are needed to adapt the technique for use in flow boiling simulations (as discussed in detail in Pan et al [37]). In the present study, the moving reference frame is set to move in the flow direction, as shown in Fig.…”

Section: Implementation Of the Moving-reference-frame Methodsmentioning

confidence: 99%

A saturated-interface-volume phase change model for simulating flow boiling

Zhang

Weibel

Garimella

2016

International Journal of Heat and Mass Transfer

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High-fidelity simulation of flow boiling in microchannels remains a challenging problem, but the increasing interest in applications of microscale two-phase transport highlights its importance. In this paper, a volume of fluid (VOF)-based flow boiling model is proposed with features that enable cost-effective simulation of two-phase flow and heat transfer in realistic geometries. The vapor and liquid phases are distinguished using a color function which represents the local volume fraction of the tracked phase. Mass conservation is satisfied by solving the transport equations for both phases with a finite-volume approach. In order to predict phase change at the liquid-vapor interface, evaporative heat and mass source terms are calculated using a novel, saturated-interface-volume phase change model. This phase change model is formulated to anchor the interfacial temperature at saturation within each iteration, and thereby acts as a robust constant-temperature boundary condition. Unlike other available phase-change models, the source terms are coupled with the local temperature explicitly; therefore, numerical oscillations around the interface temperature are not observed during iterations within a time step, which reduces the numerical cost. In addition, the reference frame is set to move with the vapor slug to artificially increase the local velocity magnitude in the thin liquid film region in the relative frame. This reduces the influence of numerical errors resulting from calculation of the surface tension force, and thus suppresses the development of spurious currents. As a result, non-uniform meshes may be used which can efficiently resolve high-aspect-ratio geometries and flow features. The overall numerical expense is significantly reduced. The proposed saturated-interface-volume model is first validated against a one-dimensional Stefan problem, and then used to simulate the growth of a vapor bubble flowing in a heated, 2D axisymmetric microchannel. The bubble motion, bubble growth rate, liquid film thickness, and local heat transfer coefficient along the wall are compared against previous numerical studies. A three-dimensional flow boiling problem is studied to demonstrate the cost effectiveness of the present approach and to highlight the transport mechanisms it can reveal in more complex domains. § Submitted for possible publication in

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“…For high Capillary number flows, setting the reference frame to move in the flow direction at the same velocity as the vapor slug will also avoid the presence of spurious currents in the liquid thin film region by increasing this nearinterface relative velocity; such a reference frame has been widely used by researchers [1,8,18,[23][24][25][26], but the purpose has been to reduce the size of the simulation domain rather than …”

Section: Spurious Current Suppression Mechanismmentioning

confidence: 99%

“…Liquid-gas slug flow in small capillary tubes and microchannels is important in heat transfer applications [1][2][3][4], micro-reaction systems [5,6], and microfluidic control [7,8]. Bretherton [9] pioneered theoretical analysis of single bubble motion in a rigid round channel under a lubrication assumption that at low Capillary numbers, viscous forces only affect the static interface profile near the wall.…”

Section: Introductionmentioning

confidence: 99%

Spurious Current Suppression in VOF-CSF Simulation of Slug Flow through Small Channels

Zhang

Weibel

Garimella

2014

Numerical Heat Transfer, Part A: Applications

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A numerical treatment is proposed to minimize the creation of unphysical, spurious currents in modeling liquid-gas slug flow using the volume of fluid-continuum surface force (VOF-CSF) method. An elongated gas slug drawn into a small circular channel initially filled with liquid is considered. To suppress spurious currents formed by numerical errors in calculation of the surface tension force at small Capillary numbers (Ca < 0.01), an artificial relative reference frame is specified with motion in a direction opposite that of the flow. An increase in the local relative velocity magnitude near the interface is demonstrated to be the key mechanism for spurious

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Numerical simulation of the pressure drop and heat transfer of two phase slug flows in microtubes using moving frame of reference technique

Cited by 31 publications

References 39 publications

Three dimensional features of convective heat transfer in droplet-based microchannel heat sinks

Three dimensional features of convective heat transfer in droplet-based microchannel heat sinks

A saturated-interface-volume phase change model for simulating flow boiling

Spurious Current Suppression in VOF-CSF Simulation of Slug Flow through Small Channels

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