Influence of Non-newtonian Properties of Liquid in Microchannels on Pressure Drop and Bubble Length

Pressure drop and bubble morphology are essential characteristics of microfluidic system design and process control. In this paper, a new type of microfluidic chip was designed and produced, including a flow-focusing device and a fluid transport device to simulate bubble generation and fluid transport in practical applications. Nitrogen and sodium carboxymethyl cellulose solutions of different concentrations were used as the gas and liquid phases. Single-phase flow and two-phase flow experiments were designed according to the commonly used flow conditions in the microchannel. By changing the flow rates of liquid and gas, the pressure drop in the fluid transport device of the two fluid states, the length of the bubble generated in the flow-focusing device, and the length of the bubble after passing through the transport device were measured, respectively. The influence of non-Newtonian characteristics of the liquid on pressure drop and the length of the generated bubbles were analyzed. The results show that the non-Newtonian characteristics of fluid have a significant effect on the pressure drop of single-phase flow and two-phase flow. Within a specific flow velocity range, the bubble length can be predicted according to the dimensionless number of the liquid. The pressure drop increases the bubble length to varying degrees.