Simulation of Droplet Based Microfluidics Devices using a Volume of Fluid (VOF) Approach
A. Chandorkar, S. Palit
Flow Science, US
Keywords: T-Junction, Coflow, Electrophoresis, Electrowetting, VOF
Abstract:This paper demonstrates that CFD simulations can be used to study important physical phenomena in Droplet based Microfluidics Devices. The Volume of Fluid (TruVOFTM) method in FLOW-3DŽ (a general purpose CFD software) has been used to study three devices. The first example is a T-junction where the continuous flow in one channel is sheared off by a dispersion flow in the perpendicular channel. The flow patterns are closely examined and compared with experiments at different times. The second example is a study of a co-flowing device where the formation and breakup of bubbles is simulated. The effect of surface tension and viscosity on bubble formation is also analyzed. In the first two examples the bubble size and frequency is related to important parameters like the width of the channel (w) and the ratio of the flow rates of the two streams (Qg/Ql). These relationships are also corroborated with experimental data. The third study is the application of the Volume of Fluid (TruVOFTM) method in predicting phenomena such as electro-wetting and electrophoresis. The contact angle is plotted against the voltage applied across a small water droplet on a dielectric material with known properties. The results are compared with the Young-Lippmann curve.