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ISSN Online: 2377-424X

ISBN Print: 978-1-56700-474-8

ISBN Online: 978-1-56700-473-1

International Heat Transfer Conference 16
August, 10-15, 2018, Beijing, China

CAPILLARY-DRIVEN FLOW IN OPEN CONVERGING MICROCHANNELS

Get access (open in a dialog) DOI: 10.1615/IHTC16.nmt.022886
pages 6955-6960

Resumo

The capillary-driven flow is widely used in practical applications, such as inkjet printer and heat pipe, getting the advantages of spontaneous fluid pumping without any external power system. Although the capillary-driven flow attracted much attention in the previous literatures, the dynamics of capillary flow in open microchannel is still unknown. Based on the Lucas-Washburn equation, the liquid imbibition length is proportional to the square root of the capillary diameter. That is, the liquid imbibition length increases as increasing the capillary diameter. D. Yang et al. (2011) found that the imbibition velocity in microchannels increases with decreasing hydraulic diameter, showing a tendency opposite to the Lucas-Washburn equation. On the other hand, M. Yang et al. (2016) reported that the imbibition velocity increase as increasing hydraulic diameter in nanochannels. So far, a comprehensive theory for the capillary-driven flow is still missing in a wide range from nanochannel to microchannel. We performed the horizontal spontaneous imbibition experiments to investigate the dynamics of capillary-driven flow in open rectangular microchannel. The liquid imbibition in the converging microchannels was compared with that in the straight microchannels and the effect of the hydraulic diameter on the liquid imbibition velocity were investigated. We found that the liquid imbibition velocity in the converging microchannel is larger than that in the straight microchannel. Also, the liquid imbibition velocity increases as decreasing the hydraulic diameter of the microchannel, against the theoretical prediction based on the Lucas-Washburn equation.