接触线(钉扎效应)力在微通道中气泡堵塞现象中所起的作用
This paper highlights the influence of contact line (pinning) forces on the mobility of dry bubblesin microchannels. Bubbles moving at velocities less than the dewetting velocity of liquid on thesurface are essentially dry, meaning that there is no thin liquid film around the bubbles. For these“dry” bubbles, contact line forces and a possible capillary pressure gradient induced by pinningact on the bubbles and resist motion. Without sufficient driving force (e.g. external pressure) adry bubble is brought to stagnation. For the first time, a bipartite theoretical model that estimatesthe required pressure difference across the length of stagnant bubbles with concave and convexback interfaces to overcome the contact line forces and stimulate motion is proposed. To validateour theory, the pressure required to move a single dry bubble in square microchannels exhibitingcontact angle hysteresis has been measured. The working fluid was deionized water. Theexperiments have been conducted on coated glass channels with different surfacehydrophilicities that resulted in concave and convex back interfaces for the bubbles. Theexperimental results were in agreement with the model’s predictions for square channels. Thepredictions of the concave and convex back models were within 19% and 27% of theexperimental measurements, respectively.