Friedrich Gunther Mugele

TL;DR: In this article, the authors demonstrate that CAH for electrowetting of water drops in ambient oil increases with increasing AC and DC voltage, which can be explained by progressive thinning of the oil layer underneath the drop with increasing voltage.

TL;DR: In this paper, a new experimental set-up and experimental strategies designed for investigating dynamic processes in molecularly thin lubricant layers are presented, which allows for two-dimensional imaging of the thickness of liquid layers confined between two atomically smooth mica surfaces.

TL;DR: In this paper, the authors present a series of experiments illustrating fundamental aspects of low salinity water flooding in well-defined model systems and show how pH and ion content of the water phase as well as the presence of model polar components (fatty acids) in the oil phase affect the wettability (i.e. contact angle distribution) of oil-water-rock systems.

Abstract: In this work we present an OpenFOAM-based electro-hydrodynamics model. We have incorporated Gauss’s Law and a free charge transport equation in an existing Volume-Of-Fluid model delivered with OpenFOAM. With the model it is possible to simulate the interaction of a fluid-fluid interface with an electric field, using perfect dielectric liquids as well as conductive liquids. Our implementation is validated using two approaches; first off, we simulate two vertically stacked liquids subjected to an electric field. The potential distribution is compared to the analytical result and a good comparison is found, using either a combination of two perfect dielectric liquids and a dielectric and a conductive liquid. For the latter case, we also find a good agreement with the theoretical relation for the surface charges. Secondly, we have simulated an artificial charge bump in a conductive liquid, and verify the charge transport equation by comparing the decay of the charge over time. Again, a good agreement with theory is found. Finally, we present a test case where we break up a droplet in an electric field. With that, we have shown to have a reliable EHD implementation in the OpenFOAM framework. For our future goal to simulate electrowetting phenomena, we require the electric field distribution in a coupled solid phase as well; we will use the current EHD model and extend it to a multi-region solver to include those effects.