# Water Flow Boiling in Micro/Mini Channels Using Volume of Fluid Model
## 1 Introduction
The available correlations in the literature for prediction flow pattern transitions have been collected and presented in [22]. [PERSON] et al. [22] coupled the LS method for tracking volume fraction with an energy jump condition for the phase change to investigate vapor bubble growth in a 200 \(\upmu\)m square microchannel. Using the constant contact angle assumption, it was reckoned that the bubble departure rate accelerated with the degree of superheat and deteriorated with increasing mass flux. [PERSON] et al. [23] employed the same model to predict that for micro-channels with inlet flow constriction, bubble growth decreased and the constriction increased flow reversal. [PERSON] et al. [24] also used the LS method, coupled with energy jump conditions for mass transfer and a simplified model for micro-layer evaporation, to reproduce the water bubble growth rate in micro-channels as predicted by experiments. The heat transfer increased for a channel size smaller than the bubble departure diameter. A CFD study of two-phase jet impingement was carried out by the authors of [25; 26]. [PERSON] et al. [27] and [PERSON] et al. [28] used nanofluids for heat transfer enhancement. Using a new method called \"pseudo boiling\", [PERSON] et al. [29] investigated FB of water in micro-channels using the VOF model. In this method, water bubbles were introduced from small pores on the wall. By matching the bubble injection and growth rate with experimental data, they could predict bubble distortion and trajectory. Similarly, [PERSON] [30] improved the efficiency of interface capture in VOF by adopting the total variation diminishing (TVD) flux-limiter algorithm in conservation equations. By incorporating the correlation of interfacial mass and energy transfer for different stages of boiling, [PERSON] et al. [31] solved the VOF model for water in microchannels, which showed good agreement with experimental results. [PERSON] et al. [32] addressed challenges while using the VOF model to capture bubble interfacial departure and proposed a criterion for selecting the proper VOF method. [PERSON] et al. [33] incorporated accurate jump conditions for heat and mass transfer across the interface, thus providing better large eddy simulation (LES) with VOF. They also benchmarked their model for the Leidenfrost phenomenon. [PERSON] et al. [34] proposed a novel mixture model that was computationally less expensive than the VOF model and was used to simulate subcooled FB in microchannels. [PERSON] et al. [35] studied bubble generation using the VOF water channel by injecting air through a 1 mm-diameterhole. [PERSON] et al. [36] considered different geometries--convergent, divergent, and normal microtubes--for their effect on water FB in terms of pressure drop. VOF and a sharp interface capturing scheme were employed for the direct numerical simulation of the evaporation and condensation [37; 38]. The capability of VOF in phase interface prediction was carefully studied by [PERSON] et al. [39] in microchannels with a diameter of 250 microns. Interface modeling using VOF was also performed by [PERSON] et al. [40] and [PERSON] et al. [41]. In the subcooled boiling regime, the core consists of subcooled liquid, and the vapor bubbles formed at the heated wall condense as they detach from the wall and reach the subcooled core. [PERSON] et al. [42] performed CFD of subcooled boiling water using the VOF model coupled with condensation correlation provided by [PERSON] et al. [43]. The computational flow regimes matched the experimental flow regimes, and the predicted HTC was acceptable. A similar study using the VOF model was performed by [PERSON] et al. [44], in which phase change was based on Nusselt, Reynolds, Prandtl, and Fourier numbers. They reproduced the bubble size and deformation obtained from experiments. Unlike other researchers, [PERSON] et al. [45] used the Eulerian phased change model to solve conservation equations for each phase separately and coupled them with pressure and interphase exchange coefficients.