Onset of Benard-Marangoni Instability on a Flat Meniscus in a Microchannel

Attention Marangoni instability in a microchannel is of interest in various heat transfer and microfluidic applications. In this work, a numerical study is conducted on a flat meniscus in a square adiabatic microchannel. The evaporative heat flux is uniform, and thus the initial meniscus temperature is uniform. However, the simulations showed that a temperature gradient perpendicular to the meniscus can also lead to an instability that starts a strong Marangoni flow, which should be a type of the Benard-Marangoni instability that was originally observed on a thin liquid layer. A new expression of the Marangoni number (Ma) is derived for the Benard-Marangoni instability in a microchannel. The threshold Ma values are obtained, providing guidance for microfluidic design.