DROPLETS MOVEMENT AND COALESCENCE IN HYDROPHOBIC MICROCHANNEL
Based on volume of fluid (VOF) method, a three-dimensional model of droplet behaviors is developed to numerically investigate the movement and coalescence of droplets in a rectangular microchannel with hydrophobic inner surface. The detailed movement and coalescence of droplets under different stream flow velocity and droplets diameter are numerically simulated to elucidate the effects of these influence factors on the coalescence time, coalescence position and the droplet interface oscillation after the coalescence. The results indicate that the coalescence occurs under the conditions of two equal-sized droplets and the binary droplets with a smaller front one. Under the propelling of the main stream, the droplet skews to the flow
direction with the contact angle hysteresis appearing. During the coalescence process, the oscillation of
contact area between the coalescent droplet and channel wall occurs, which is damped to be a stable value at
last. With the increase of stream flow velocity, the coalescence time decreases and the coalescence distance
increases at first and then decreases.