Numerical investigation on flow regime transition mechanism and length prediction method of droplet in T-junction by electric field

Abstract

Although droplet microfluidics has received attention and research in the fields of chemistry and materials in recent years, research on electric field modulation of microchannel droplets is currently fragmented. In this paper, the effect of electric field and flow rate ratio on the behavior of discrete-phase flow in systems with different viscosity ratios was simulated. Subsequently, we delineated the regions of slug flow, drip flow, jet flow, and parallel flow under different parameters according to the simulation results, and investigated the mechanism of electric field manipulating the transformation of the above four flow types by combining the velocity vector diagram with the force situation. Additionally, in order to fill the gap in methods for predicting droplet length in T-junction microchannels under the presence of electric field, we present a scaling law for predicting droplet length that couples the effects of electric field, velocity, and viscosity. And it was verified that the error of the model built based on this method is less than 12 % when the flow ratio is less than 1.