Convection heat transfer in electrostatic actuated liquid droplets for electronics cooling

In this paper, the internal flow and heat transfer inside the electrostatic actuated droplets are studied for different droplet velocities by means of detailed flow computations. It is shown that the internal droplet flow exhibits a parabolic characteristic at one hand and that the presence of two convection cells decreases the heat transfer to the lower part of the droplet, thereby limiting the overall heat transfer through the droplet. A typical enhancement of the heat transfer with a factor 2 is achieved with respect to the minimal value that would be obtained assuming heat conduction as the only means of heat transfer in the liquid. Further an analytic lumped model is presented to estimate the transient average droplet temperature with an accuracy of 5% compared to the full transient computational fluid dynamics modelling.