EAGER: The Dynamics of Large Buoyant Plumes

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This award is for the study of vertical plumes that are initiated from very large fires. The classic example is detonations of nuclear weapons which would result in massive fires, sending soot and ash far up into the atmosphere. As has been documented with volcanoes, if the materials reach a certain level in the atmosphere they can stay suspended for a long time and cool the surface of the Earth. This project will revisit the concept of plumes originating from large fires using modern computational tools. The research may have policy implications and will contribute to the education and training of the next generation of scientists.The overarching goal of this EAGER award is to develop a general theory for the flow above very large fires, such as those initiated by the detonation of a nuclear weapon. The lead scientist for this project makes the case that given the basic characteristics of a fire, we are unable to predict the buoyancy of the resultant plume. And without a buoyancy estimate, we cannot predict the plume's level of neutral buoyancy or the height at which aerosols will ultimately reside in the atmosphere. The research team will formulate a theory that provides estimates of the initial height, horizontal width, and characteristic buoyancy of the fluid emerging from the spin-up layer. With this theory in hand, the researchers will initialize the vertical plume and study the fate of the air launched upwards in the vertical plume. The aim is to formulate a theory for the plume's level of neutral buoyancy. The approach will be to climb up the hierarchy from 2D dry unstratified initial results to a comprehensive theory for realistic plumes in a 3D moist stratified atmosphere. The results of this theory will be validated against high-resolution simulations from Large Eddy and Direct Numerical Simulations (LES and DNS).This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.