Hydrodynamics of gas-liquid Taylor flow in microchannels

• Main Author: Abadie, Thomas
• Format: Others
• Published: 2013
• Online Access: http://oatao.univ-toulouse.fr/11986/1/abadie.pdf

This thesis focuses on the hydrodynamics of gas-liquid Taylor flow (or slug flow) in microchannels. These flows, which are generally dominated by surface tension forces, have been investigated in rectangular channels of various cross-sectional aspect ratios by means of both experimental visualizations and numerical simulations. The first experimental part aims at characterizing the bubble generation process (bubble length and frequency of break-up) depending on the operating conditions, the fluid properties, as well as the junction where both fluids merge. Numerical simulations of fully developed Taylor flow have been carried out with the JADIM code. The computation of such surface tension dominated flows requires an accurate calculation of the surface tension force. Some limitations of the Volume of Fluid method have been highlighted and a Level Set method has been developed in order to improve the calculation of capillary effects. Both methods have been compared in detail in terms of spurious currents. 3D numerical simulations have been performed and the influence of the capillary number, as well as the effects of geometry have been highlighted. Inertial effects have been taken into account and their influence on the pressure drop has been shown to be non-negligible. Mixing in the liquid slug has also been studied.