Effects of cross-section geometry of capillary on the evaporation from the meniscus

Effects of cross-section geometry of capillary on the evaporation from the meniscus have been investigated by adopting several circular and rectangular capillaries. The evaporating meniscus shape, evaporation rate and flow near the evaporating meniscus of various liquids such as water, ethanol and methanol are determined. The shapes of water and ethanol menisci in circular capillary are quite different from each other due to the difference in surface tension. But the difference in meniscus shapes is relatively small in rectangular channel. The averaged evaporation fluxes in rectangular channel are much larger than that in circular capillary. The rotating vortex motion is observed near the evaporating menisci of ethanol and methanol except for the case of methanol in 200 x 20-mu m capillary. The reason for this is considered to be the existence of the corner menisci at the four corners.