Flows in rectangular microchannels driven by capillary force and gravity

In this study, the theoretical mathematical model of flow in microchannel driven by capillary force and gravity is formulated from the Navier-Stokes equations. A close form solution to predict flow time was developed, and experiments have been set up to investigate and verify the flow times in microchannels. From the results, the predicted flow times show reasonably good agreement with the corresponding experimental flow times. Moreover, when the microchannel height is small, the effects of gravity force become less obvious; namely, the capillary becomes the dominant source to drive microfluidic.