Devesh Ranjan has received a 2015 Stewardship Science Academic Alliance (SSAA) Award from Department of Energy-National Nuclear Security Adminstration for his three year project, Detailed Measurements of Turbulent Rayleigh-Taylor Mixing at Large Atwood Numbers.
Established in 2002, the Stewardship Science Academic Alliances Program funds academic research in the areas of materials under extreme conditions, low energy nuclear science, radiochemistry, and high energy density physics. One of the goals of the program is to fund research projects at universities that conduct fundamental science and technology research that is of relevance to stockpile stewardship.
With this award, Ranjan and his research team will extend their research on understanding the flow physics associated with the Rayleigh-Taylor driven mixing and turbulence using the unique SSAA supported Multi-layer Rayleigh-Taylor Gas-Tunnel (MRTGT) facility at Georgia Tech. 
Ranjan's studies on RT mixing, a key hydrodynamic process during ICF implosion, directly impact fundamental understanding of the flow physics and validate engineering models for ICF target design and energy deposition.
During the past six years, the SSAA MRTGT has produced numerous firsts that include: the first measured turbulent mass fluxes, and associated spectra and p.d.f’s at high density ratios (large Atwood numbers ~ 0.75); the first measured conditional two-fluid measurements, suitable for turbulence model validation and development; and the first molecular mix measurements at high Atwood number. The research has also produced an important new hot-wire diagnostic that permits detailed data collection from multi-component gas streams, and it is this development that brings the MRTGT to the forefront for Rayleigh-Taylor experiments.
Ranjan's project centers on the SSAA Multi-layer Rayleigh-Taylor Gas-Tunnel (MRTGT) facility with two main research tasks: 1) to continue extensive data collection from MRTGT up to its maximum at Atwood number of 0.75 and 2) to create a three-fluid Rayleigh-Taylor mixing layer experiment to explore multi-layer mixing in an ICF capsule. Detailed data for miscible fluids, suitable for ICF model development and validation, is not available at an Atwood number of 0.75 and there is a similar lack of detailed data for multi-layer configurations, typical of ICF targets. The proposed research addresses these deficiencies by way of the MRTGT and its advanced diagnostics. Aside from the immediate impact on ICF target design, the collection of RT mixing data has a broad impact for prediction of other buoyancy driven flows such as climate, oceans, oil recovery (salt-domes), and fuel spray formation. Thus, Ranjan's research sits as a cornerstone to fundamental science that underpins ICF, energy, and climate.