Numerical study on gas-liquid interface in a microchannel

A bubble or droplet can be driven in a microchannel due to the thermocapillary force controlled by microheaters, which comes from the surface tension imbalance. Though practical optical switches based on this principle have been developed by micromachining technique, there has been no contribution of fluid dynamics both experimentally and analytically. In order to treat gas-liquid interface accurately in a microchannel, it is necessary to improve the models of surface tension and contact angle. A new numerical scheme is developed based on C-CUP and Level-Set function method with CSF model and is able to calculate the surface tension distribution precisely. It is the first time to simulate the thermally-driven bubble in a microchannel and the obtained results show good agreements with experimental results qualitatively. Comparisons with the conventional numerical schemes and fundamental mechanisms of the thermally-driven interfaces are also discussed.