Nathan E. Miller, Ph.D.Sandia National Laboratories
Friday, April 24th, 2025, 3:00 - 4:00 PM
Jett Hall, room 109
Title: Seminar Title: Numerical Simulations of Hypersonic Flows
ABSTRACT: High-speed flight in the atmosphere (e.g., transonic to hypersonic) exposes flight vehicles to a variety of environments not experienced in the subsonic regime. Considerable engineering effort is required to address the challenges presented by these environments (e.g., vibration, thermal protection, communication) to ensure survival and optimal performance. Dr. Miller will present on various recent research projects related to supersonic and hypersonic boundary layer flows conducted at Sandia National Labs. First will be a discussion on optical distortions through turbulent boundary layers. When collimated light passes through high-speed turbulence, like that flowing over the surface of a supersonic or hypersonic vehicle, that light is distorted due to the density perturbations of the turbulence. The resulting beam is then blurred when it reaches a sensor aperture, resulting in degraded signal integrity. This behavior is further exaggerated when the boundary layer is laden with plasma as is often the case for vehicles reentering earth’s atmosphere. The degraded propagation of microwaves through turbulent plasma layers will be briefly discussed second and recent advances in understanding signal entrainment in plasma layers will be shown. Finally, the results of a recent international validation challenge organized by Sandia’s aerosciences department will be discussed. This challenge invited participants from industry, government, and academia to blindly simulate an axisymmetric shock-induced separation in a transonic flow by only providing initial and boundary conditions. Upon completion all participants’ data was compared to a series of wind tunnel tests in order to identify gaps and weaknesses in modeling and modeler strategies.
BIO: Nathan E. Miller, Ph.D., is a Principal R&D Aeronautical Engineer in the Computational Aerosciences Department at Sandia National Laboratories in Albuquerque, New Mexico. His work includes a range of projects in model development, aerodynamics, aerothermodynamics, structural response, and flight dynamics problems spanning Mach regimes from subsonic to hypersonic. This includes working with Sandia’s wind-tunnel and flight-test experimentalists on the design and performance of test vehicles, validation work for fluids models based on experiments, the simulation of complex flows using tools ranging from low-fidelity (Euler) to high-fidelity (Direct Numerical Simulation), aero-thermal analysis for hypersonic flight vehicles including US strategic weapons systems, and many other projects related to US national security and the Nuclear Security Enterprise.
