Marangoni Bifurcation Flow in a Microchannel T-Junction and Its Micropumping Effect: A Computational Study

We discuss a bifurcation phenomenon of Marangoni flow in a microchannel T-junction and its novel unidirectional pumping effect. The T-junction is formed by a main channel connected with a liquid reservoir and a side channel outlet to the atmosphere. A volatizing meniscus is formed in the side channel and Marangoni convections are generated due to the non-uniform evaporation on the meniscus. It is found for weak evaporations (Ma < 270) the Marangoni convections are symmetrical. However, for intense evaporations (Ma >270), the initial inward symmetrical Marangoni convection becomes unstable and converted into one single vortex flow. Moreover, the single vortex induces a steady unidirectional flow in the main channel, acting like a pump.