Influencing factors and size prediction of bubbles formed by flow focusing in a cross-channel

Abstract

Formation of uniform-sized bubbles in microchannels by gas–liquid two-phase flow is the basis for applications such as microreactors and micro/nano preparation. In this study, a two-phase flow regime was investigated in a cross-channel controlled by the liquid-phase flow rate and gas-phase pressure. The size of the monodisperse bubbles was predicted based on the factors influencing the bubble length obtained from the dimensional analysis. The transition line between flow patterns was calculated using the bubble length prediction equation, and the flow phase diagram of the gas–liquid two-phase flow in the microfluidic channel was completed. The relationship between the inlet conditions, including the gas-phase pressure and liquid-phase flow rate, and the flow pattern in the microchannel was studied in depth. The results are relevant to the design of microbubble production devices and the precise control of bubble size.