Mason Eastman with Harsh Mathur
Conductors as a model for elliptical coffee stains
In electrostatics, conductors exhibit a number of interesting properties. Among these is the ‘lightning rod’ effect, whereby electric fields are significantly greater near areas of high curvature. In 1997, Nagel et al. published a paper likening the behavior of a spilled liquid on a surface – e.g., a drop of coffee on a table – to a conductor. When a drop of coffee is spilled, the water evaporates in such a way that the remaining solute is concentrated on the boundary in a way analogous to the ‘lightning rod’ effect. We will extend this idea to an elliptical, rather than spherical, drop by applying mathematical models and simulations. We expect a higher concentration of solute on the areas of higher curvature.