My student, Dr. Tianshu Zhang, and myself recently published a modified long range acoustic propagation model that handles turbulence in the atmosphere. The abstract is We present a semi-empirical long-range low-frequency acoustic propagation model, which accounts for atmospheric turbulence. Ostashev and Wilson’s scattering model is combined with a ray-theory based refraction model to account for …
Author Archives: saemiller
NASA Langley Feb. 2023
Caverns of the Wind
Silent are the caverns of the wind, But within them, a secret lies pinned Like Pandora’s box, locked up tight Holding within, a glimmer of light For in these tunnels, dreams did reside And hope for the future, they did provide But like Pandora’s box, they were lost Their secrets stolen, at a great cost …
The Tempest
In the skies above, a tempest swirls,Its winds, a cascade of power unfurled. Turbulence, a beast with might so true, Its roars, a symphony in shades of blue. The winds, the rain, the lightning’s bright gleam, A show of strength, a testament supreme. Turbulence, cascade, and acoustics play, A performance, unmatched, in skies so grey. …
A Note on Critical Thinking
Miller, S. A. E., “Note on Critical Thinking,” NASA Alumni Association Magazine, Dec., 2022. pp 5. (one-page) One might visit any leading university campus in the United States and ask the graduate faculty training future researchers one question, “what is the purpose of educating students?” One of the most frequent answers is to create critical …
Viscosity Coefficients
Often viscosity is isotropic, meaning that it is the same in all directions. In such a case, only two of the six components of the strain rate tensor are independent, so two coefficients of viscosity can be used to describe the viscous behavior of the fluid. These two coefficients are related by -2/3. This relationship …
The NASA X-59 at AIAA SciTech 2023
Saint Augustine in His Study
Via photograph at Smithsonian in DC, Fine-Arts Museum.
AIAA SciTech 2023
This year, some of my students and collaborators are going to the AIAA SciTech conference in the DC area in the National Harbor, MD. We are presenting two particular papers. The first involves hypersonic flow-fields and the second involves acoustics and aerodynamic experiments. The citations, papers, and presentations are:
MLK Day 2023
Well, I don’t know what will happen now. We’ve got some difficult days ahead. But it doesn’t matter with me now. Because I’ve been to the mountaintop. And I don’t mind. Like anybody, I would like to live a long life. Longevity has its place. But I’m not concerned about that now. I just want …