March 31, 2025, Amal Sahai, NASA Ames

4:00 p.m.
190 Goodwin Hall

" Computationally efficient 3D radiation and a recipe for multi-physics hypersonic simulations"

Abstract:   NASA is currently planning missions with entry, descent, and landing (EDL) phases or aerocapture maneuvers involving increasingly higher velocities, e.g., Mars Sample Return - Earth Entry Vehicle (MSR-EEV) and denser atmospheric conditions, e.g., Dragonfly. Additionally, more ambitious objectives such as human exploration of Mars would necessitate changes in spacecraft systems including everything from new aeroshells, improved parachutes, and retro propulsive braking. These extreme conditions and complex mission architectures make it imperative that the various physical phenomena shaping hypersonic flight such as thermochemically reactive flows, radiation, ablation, and multiphase effects be modeled in a holistic manner in order to obtain reliable predictions for vehicle design requirements. Furthermore, the drive towards improving safety, mission viability, and payload potential requires that the simulation turnaround times are minimized to enable exhaustive design trade studies. Thus, it is critical that software solutions that are available at NASA combine multi-scale physics, efficient algorithmic choices, and the ability to exploit the full gamut of capabilities on offer on modern HPC systems.

Bio:   Amal Sahai is a research scientist in the Entry Systems and Technology Division at NASA Ames Research Center. He is involved in the development of multi-physics numerical algorithms and high-performance computing (HPC) codes for characterizing hypersonic planetary entry and assessing spacecraft safety. In addition to aerothermal computational fluid dynamics, he has contributed to building new simulation capabilities for dust-laden flows, three-dimensions (3D) radiative heat transfer, and electromagnetics. Previously, Amal received his Bachelor of Technology in Mechanical Engineering from the Indian Institute of Technology Guwahati in 2012. He completed his Master of Science and Ph.D. in Aerospace Engineering from the University of Illinois at Urbana-Champaign in 2015 and 2019, respectively. The focus of his graduate studies was on bridging the gap between first principles based detailed quantum chemistry databases and large-scale 3D simulations for practical problems. The result was a reduced-order modeling framework for non-Boltzmann thermochemistry and radiation that could be incorporated into practical numerical design studies.