Optimization of Shear Driven Droplet Generation in a Microfluidic Device

Hydrophilic and lipophilic interfaces of fluids play an important role in the formation of droplets. A large collection of droplets constitutes emulsions of water dispersive phase into oil continuous phase. Since droplet generation forms the basis of the manufacturing of emulsion, great efforts have been made to understand the science, technological and industrial problems associated with the generation of droplets. This paper presents the optimization of a novel method of droplet generation [1] in a microchannel resulting from the laminar co-flow of water and oil in a T type channel. Water in oil droplets are formed with olive oil (interfacial tension 28mN/m, viscosity 84mPa/s, density 918Kg/m3). At the T-junction, the water stream sent through the middle channel is sheared and cut by the oil stream sent through the outer channel. Competition between interfacial tension and the Laplace pressure at the oil/water interface results in droplets of finite diameter. Fluid properties such as density, viscosity and surface tension and the flow parameters such as pressure, mass flow rate and velocity are varied at the inlets and outlets to optimize size, frequency and periodicity of droplets using CFD-ACE+, a multiphysics modeling tool (CFDRC, Huntsville, AL).