Capillary flow in open microchannels with rectangular cross-sections: a numerical study

Liquids in microchannels are driven by capillary force and spontaneously penetrate into the channels. Predicting and controlling such capillary-driven flow is important in various industrial fields (e.g., high-performance heat exchangers).

It is known that capillary flow is well described by the Lucas-Washburn theory. However, for open microchannels, the applicability of the Lucas-Washburn theory is not yet explored due to the existence of free liquid-gas interfaces, and remains as a challenge.

In this study, numerical simulations of capillary flow in open microchannels with rectangular cross-sections are performed to analyze the structures of liquid-gas interfaces and liquid flow. It is shown that the present simulation results fairly agree with the existing experimental observations and theoretical predictions.