Research Description
Earth’s magnetic field is essential for life and has been generated by swirling motions of molten iron in the planet’s outer core for about 4 billion years. Earth’s solid inner core, however, is much younger, and models struggle to create enough motion to generate a strong field without an inner core. Douglas Kelley’s team hypothesizes that roughness where the core meets the mantle promoted flows that were fast enough to create the field, even before the inner core was formed. To test this, they will perform laboratory experiments on convective flows with rough boundaries in a rotating system.
Dr. Kelley’s team will drive flow with thermal convection, heating from the bottom and cooling from the top, with the entire apparatus rotating steadily to mimic planetary rotation. They will add roughness of varying size and shape to the vessel walls. They will perform experiments with liquid metal, whose high thermal conductivity is a good model for the liquid metal in Earth’s core, and with water, whose transparency allows the high-resolution, three-dimensional velocity measurements they will make.
Research Impact
Dr. Kelley’s work strives to resolve the “new core paradox,” that is, the current mystery of how Earth’s magnetic field arose before the inner core formed. Few, if any, prior experiments have studied rough, rotating convection in liquid metals. The team’s detailed measurements of liquid metal flows and dense three-dimensional measurements of water flows will be shared publicly and will advance the field because few prior experiments have produced similar data.
Their studies of the little-explored physics of rotating, rough convection could also have applications to oceans and atmospheres, which likewise rotate, are driven by temperature gradients, and encounter uneven boundaries such as mountains and valleys.
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related links
Experimental Physics Investigators Initiative 
Science
University of Rochester, Department of Mechanical Engineering
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