Tom Schwartzentruber
Professor of Aerospace Engineering and Mechanics
University of Minnesota

Predicting what happens as a hypersonic vehicle flies through the atmosphere involves a lot of interesting physics. The strong shock wave, generated ahead of the vehicle, superheats the air to thousands of degrees and partially dissociates the air into atomic oxygen and nitrogen. Surrounded by this high-temperature shock layer, the vehicle heat shield experiences large heating rates and must simultaneously withstand high temperatures and intense surface chemistry driven by reactive atomic species. Furthermore, as the shock-heated gas flows around the vehicle, the flow can transition from smooth laminar flow to chaotic turbulent flow and can form complex shock interactions near control surfaces. Predicting such effects requires understanding the interplay between fluid dynamics, thermodynamics, and chemical kinetics; a research field referred to as aerothermodynamics.

In this talk, I will focus mainly on our current understanding of the high-temperature shock layer. I will explain how we have reached the point where this thin shock layer (often on the order of one centimeter thick) can be studied at the scale of individual molecular collisions. In fact, simulations can now be performed where the only model input consists of the forces between atoms as dictated entirely by quantum chemistry. I will present results from such first-principles simulations along with comparison to experimental shock-tube data, and I will discuss some of the new physical insights gained. I will conclude the talk by highlighting the next big challenge of pursuing molecular understanding for gas-material interactions. This is an exciting field driven not only by NASA and the Department of Defense, but also by commercial endeavors to field satellite mega-constellations in low Earth orbit.

About the speaker...

Tom Schwartzentruber received his Bachelor’s degree in engineering science and his Master’s degree in aerospace engineering from the University of Toronto. He then received his doctorate degree in aerospace engineering from the University of Michigan. For his doctorate work he received the AIAA Orville and Wilbur Wright graduate award. He joined the faculty in the Aerospace Engineering and Mechanics department at the University of Minnesota in 2008, after which he received a Young Investigator Program Award from the AFOSR and the University of Minnesota Taylor Career Development Award for exceptional contributions by a candidate for tenure. He specializes in particle simulation methods such as direct simulation Monte Carlo (DSMC) and molecular dynamics (MD), including coupling such methods with each other and with continuum computational fluid dynamics (CFD) methods. Currently, his research group is involved in a number of projects spanning hypersonic nonequilibrium reacting flows, high-temperature gas-surface interactions, hybrid particle-continuum methods, and micro-scale flows.