Numerical Investigations of Digitized Heat Transfer

In the rapidly evolving field of high-powered electronics, hardware continues to become smaller and more powerful. The consequence of this trend is tightly packed electronic components and high heat generation rates that demands more efficient thermal management techniques. In this paper, digitized heat transfer using electrowetting on a dielectric is examined as a potential solution. A numerical simulation of translating microdroplets in a parallel plate and axisymmetric pipe is studied. From previous studies, it is known that translating microdroplets have improved heat transfer over continuous flow that is highly dependent on the height to length ratio of the droplet. This paper finds that in addition to the height to length ratio, Reynolds numbers has a significant effect on droplet velocity profile as well as droplet temperature distribution. At high Reynolds numbers, the center line velocity increases beyond what is predicted in a Poiseuille flow, thus increasing circulation and the Nusselt number of the droplet. Additionally, it is found that the center line velocity enhancement is accompanied by the development of inflection points in the velocity profile, indicating more susceptibility to instability development and potential transition to turbulence. Nevertheless, the change in Reynolds number was found to not have a significant effect on the location of the Nusselt number peaks along the channel length which is correlated with the circulation length of the droplet.