Three Dimensional Effects in Taylor Flow in Circular Microchannels

Abstract

The gas-liquid Taylor flow regime in microchannels is of great interest to a range of industries (e.g. electronics cooling, automotive, biomedical, aerospace and chemical processing) as the rates of heat and mass transport are significantly enhanced in Taylor flow when compared with laminar, fully-developed single phase liquid-only flow. The bubble shape and flow are generally assumed to be axisymmetric and steady (in a frame of reference moving with the bubble) in Taylor flow in millimetre-size circular channels. Our experiments performed using a combination of highspeed imaging and micro-Particle Image Velocimetry (micro-PIV) techniques have investigated the case of Taylor flow for an ethylene glycol-nitrogen system in a horizontal channel of 2 mm diameter, where the bubble shape was observed to show significant non-axisymmetric behaviour. To further understand the non-axisymmetric flow behaviour a periodic, three-dimensional computational fluid dynamics (CFD) model employing the Volume of Fluid (VOF) method (using ANSYS Fluent) with geometric reconstruction to capture the gas-liquid interface was developed. A combination of experimental and computational techniques gives insight into the flow physics for the case of horizontal Taylor flow where three dimensional effects are important.