Study on the Flow and Heat Transfer Characteristics of Micro-Scale Droplets and Fluid on Dynamic Liquid Film Condition by Lattice Boltzmann Method

Abstract

The lab on a chip is of great value in the analytical chemistry, biology and pharmacy. So that it is very important to study the formation and control of droplet in chips. The fluid flowing under the condition of dynamic liquid film is researched innovatively in this paper. Its inspiration is derived from bionics (fish skin, etc.), which has a broad application prospect in reducing the resistance in water and weakening the heat transfer. Dynamic liquid film refers to the dynamic thin liquid layer with the hydrophilic property on the surface of wall under the pressure of outside fluid flow. The insolubility between liquid film and fluid creates a relatively stable flowing environment. In this paper, the formation and influencing factors of the droplet in the microfluidic chip are studied by the Lattice Boltzmann method (LBM), and the flow and heat transfer characteristics of fluid in microchannel is studied with microfluidic chip as the carrier under the condition of insoluble dynamic liquid film existing on the wall surface. LBM has certain advantages in boundary processing, parallel operation and tracing phase interface automatically. Using SC model of LBM (for two component flow), the process of formation and movement of the droplet in microfluidic chip are simulated numerically after verified by Laplace‘s law. The result shows that the hydrophobic characteristics between the discrete phase and the wall surface and increased flow rate of the continuous phase will decrease the droplets’ volume and increase the producing frequency. In addition, the fluid flow in the microchannel is simulated under the condition of insoluble dynamic liquid film on the wall surface. The simulation result shows that when the fluid flow rate increases, the friction loss decreases and the heat transfer capacity decreases with the existence of the liquid film. The lower the dissolution trend between fluid and liquid film is, the greater the variation trend of fluid parameters will be. By comparing the results of experiment and simulation, the consistent results are obtained.