This article presents a comprehensive review of numerical methods and models for interface resolving simulations of multiphase flows in microfluidics and micro process engineering. The focus of the paper is on continuum methods where it covers the three common approaches in the sharp interface limit, namely the volume-of-fluid method with interface reconstruction, the level set method and the front tracking method, as well as methods with finite interface thickness such as color-function based methods and the phase-field method. Variants of the mesoscopic lattice Boltzmann method for two-fluid flows are also discussed, as well as various hybrid approaches. The mathematical foundation of each method is given and its specific advantages and limitations are highlighted. For continuum methods, the coupling of the interface evolution equation with the single-field Navier–Stokes equations and related issues are discussed. Methods and models for surface tension forces, contact lines, heat and mass transfer and phase change are presented. In the second part of this article applications of the methods in microfluidics and micro process engineering are reviewed, including flow hydrodynamics (separated and segmented flow, bubble and drop formation, breakup and coalescence), heat and mass transfer (with and without chemical reactions), mixing and dispersion, Marangoni flows and surfactants, and boiling.

Numerical modeling of multiphase flows in microfluidics and micro process engineering: a review of methods and applications

Review of computational studies on boiling and condensation

This article describes the implementation and validation of a nucleate boiling model in the volume-of-fluid solver of OpenFOAM. Emphasis is put on the implementation of the contact line evaporation, which can typically not be resolved by the numerical grid, and on the conjugate heat transfer between solid and fluid. For validation, the sucking interface problem and the growth of a spherical bubble have been simulated successfully. In order to validate the contact line model and the conjugate heat transfer, the growth of a bubble from a heated steel foil has been calculated.

CFD Simulation of Boiling Flows Using the Volume-of-Fluid Method within OpenFOAM

Numerical investigation of hydrodynamics and heat transfer of elongated bubbles during flow boiling in a microchannel

A sharp-interface phase change model for a mass-conservative interface tracking method

Evaporation model for interfacial flows based on a continuum-field representation of the source terms

Tubes with subsurface mini- and micro channels are widely used in boiling devices. Today, the design of these tubes is based on empirical investigations because reliable theoretical or numerical design methods are not available, and the heat transfer performance characteristics vary strongly e.g. for different fluids, system pressures and heat fluxes. The presented study approaches the subject of interest from 3 different paths: (i) macroscopic heat transfer performance measurements; (ii) optical measurements of the thermal and hydrodynamic phenomena inside the subsurface channels with very high spatial and temporal resolution; (iii) development of a computational model. While path (i) is a standard procedure in the scientific community, path (ii) is a completely new approach, and only the combination of (i) and (ii) is a solid basis for the physically based model development in path (iii). Tubes with different subsurface channels and micro pin-fins are used in combination with different fluids at different system pressures. The results are presented and discussed.Copyright © 2008 by ASME

Nucleate Pool Boiling on Tubes With Subsurface Mini and Micro Channels

Experimental investigation of fuel evaporation on microstructured surfaces for microcombustion

Pool boiling heat transfer from tubular microstructured surfaces in saturated FC-72

Zur Verbesserung des Warmeubergangs beim Behaltersieden haben sich in der industriellen Anwendung Hochleistungsverdampferrohre mit hinterschnittenen Oberflachenstrukturen etabliert. Der gute Warmeubergang wird durch die Verdampfungsvorgange in den hinterschnittenen Kanalen bedingt. Zur Identifikation dieser auf Mikrolangenskalen ablaufenden Vorgange wurden mittels optischer Messverfahren die lokalen Temperaturen und die Dynamik der Phasengrenze in den Kanalen untersucht.

F. Wondra

Papers

Evaporation model for interfacial flows based on a continuum-field representation of the source terms

Nucleate Pool Boiling on Tubes With Subsurface Mini and Micro Channels

Experimental investigation of fuel evaporation on microstructured surfaces for microcombustion

Pool boiling heat transfer from tubular microstructured surfaces in saturated FC-72

Experimentelle Untersuchung der Mikroskalenverdampfung in hinterschnittenen Oberflächenstrukturen