An Electromagnetically-Driven Flow Cell for Studying Flow Instabilities

Flow instabilities occur when there is a sudden change in the behavior of a fluid as system parameters are varied. Typically, these instabilities involve spontaneous symmetry breaking and are mathematically closely related to second order phase transitions in statistical mechanics. In this talk, we will discuss a simple table-top experiment in which flow instabilities are induced in a thin layer of electromagnetically-driven electrolyte. This apparatus can be constructed inexpensively (~$300), takes minutes to set up, and is similar to systems used by scientists to understand the phenomenology of large-scale motions in atmospheric and oceanic flows. The apparatus can be used to demonstrate several different ideas in fluid dynamics including Reynolds similarity and flow instabilities using basic flow visualization, but can also be made quantitative using standard flow measurement techniques like particle image velocimetry. Such measurement techniquest are widely used in engineering applications ranging from aerodynamics and materials testing to biomechanics and cancer research.