Electrowetting on Dielectric (EWOD) method is widely used to actuate microdroplets sandwiched between parallel plates in microfluidic chips. However, utilization of this method to transport liquid plugs in conduits has not been comprehensively studied to date. In this paper, the EWOD actuation of a liquid plug confined in a microchannel of rectangular cross section is numerically studied using OpenFoam. The effect of various parameters including electrowetting dimensionless number (η), contact angle hysteresis (CAH), dynamic viscosity and surface tension coefficient on transport velocity is investigated by employing an interactive simulation approach. The transport velocity can be considered a gauge to evaluate the actuation efficiency. The results show that, increasing η has a greater impact on velocity for larger values of CAH. In addition, it is shown that the average velocity increases linearly by increasing the surface tension coefficient. An inverse relationship between velocity and dynamic viscosity is also observed. These trends are in accordance with the theoretical model developed for a similar case in the literature. To estimate the maximum possible gap size between electrodes (MPGS), non-actuated distance travelled before the liquid plug comes to stop is evaluated. The results show that by decreasing the values of η, the effect of changing CAH on MPGS becomes more substantial.

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