3-D numerical simulation of contact angle hysteresis for slug flow in microchannel

Water management that ensures the effective removal of produced water in the microchannel at the cathode is critical for the performance of PEM fuel cells. The small dimension and confined space of channels leads to the importance of the surface force in determining the dynamics of inside liquid slugs The present study focuses on the simulation of the slug detachment process in the micro-channel, using a contact angle hysteresis model within the framework of VOF approach. Based on solving the nonlinear equations accounting for the relationship among volume fraction, interface position, and contact angle, a special model is developed to replicate the hysteresis effect. In addition, a special algorithm is introduced to simulate the thin liquid/gas films. A systematic comparison between experiment and simulation has been conducted and the quantitative match in terms of slug dimensions is achieved for a wide range of flow conditions. The simulation reveals that the contact angle distribution along the slug profile could be approximated using piecewise linear function. The calculation also shows that the contact angle hysteresis might be responsible for several phenomena observed in experiment, such as slug instability.