Sandia Labs FY22 Laboratory Directed Research & Development Annual Report

FY22 ANNUAL REPORT

ENABLING FULLY PREDICTIVE SIMULATIONS USING DISRUPTIVE COMPUTATIONAL MECHANICS AND NOVEL DIAGNOSTICS FOR FLUID-TO-SOLID TRANSITIONS.

Accurately capturing solidification of fluids and the development of residual stress is critical for fully predictive simulations for numerous applications in geoscience, nuclear safety, manufacturing, energy production, and bioscience. Researchers on this LDRD project developed, implemented,

showed solidification in regions of low applied stress near free surfaces and far from the inlet. These improved models for the birthing of residual stress will substantially improve predictions of Sandia’s encapsulation processes. This project resulted in five publications consisting of one in

Stress birth and death of a fluid-to-solid transaction: (left) fluid birth, and (right) the solid transaction.

and demonstrated advanced constitutive models with yield stress to represent both fluid and solid behavior simultaneously. They also presented results from literature models and demonstrated the first finite element results for the Kamani Donley-Rogers model that was developed by Sandia Alliance partners at the University of Illinois at Urbana-Champaign (Illinois). Predictions were compared to novel experimental results of gravitational settling of yield stress fluids in a Hele-Shaw cell. Both experiments and simulations approximated in impulsively operated ground-test facilities, with test times of a few milliseconds at best, placing high-acquisition-rate measurements at a premium. Wavelength-tunable burst-mode laser capabilities for temperature and chemical species detection at 100-kHz rates were developed, improving on existing measurement speeds by 2-4 orders of magnitude and increasing data yield from a single laser shot to over 100 measurements during a single test.

Physical Review Letters in 2021, two in the Journal of Non-Newtonian Fluid Mechanics (1) (2), and the Physics of Fluids in 2022, and one in the Journal of Rheology in 2023. Additionally, this Sandia team had numerous collaborators from industry (3M, Proctor and Gamble), the government (U.S. Army Engineering R&D Center), and Sandia Alliance partners from Illinois, University of New Mexico, Georgia Tech, and the University of Utah. (PI: Rekha Rao) The team characterized nonequilibrium thermal environments and velocities in the shock-tunnel flow, capturing transient temperature changes in excess of 4000 K, and imaging hypersonic wake transients. These new capabilities are being applied for unique hypersonics data sets and informing new modeling and design tools at Sandia. The work was conducted in collaboration with Alliance partner Purdue University, who transferred expertise on tunable high-repetition rate laser sources to Sandia. (PI: Sean Kearney)

HIGH-SPEED DIAGNOSTIC AND SIMULATION CAPABILITIES FOR REACTING HYPERSONIC REENTRY FLOWS. Hypersonic flight environments are often

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