My former student, Dr. Alex Carr, along with Dr. J. Lonzaga, who are both of NASA Langley Research Center, and myself published an article on the propagation of sonic boom through the turbulent atmosphere. Abstract: The effects of atmospheric boundary layer turbulence on the loudness variability of a sonic boom N-wave and shaped boom are …
Category Archives: Fluid Dynamics
Fall 2023
Who would have thought that 7 years go by so quickly at the University of Florida. This year I am teaching introduction to computational fluid dynamics. The last time I taught it was before COVID in the fall of 2020. I am working on a new design program for nozzles. I am basing it on …
DARPA Director’s Fellow
I am very fortunate to be awared the 2023-2024 DARPA Director’s Fellowship. The linked article from my department is at the following link: https://mae.ufl.edu/2023/08/09/darpa-directors-fellowship-awarded-to-steven-a-e-miller/ The article text is below Associate Professor Steven A. E. Miller, Ph.D., is awarded the Director’s Fellowship from the Defense Advanced Research Projects Agency (DARPA) for 2023-2024. The award recognizes technical …
AIAA Paper: Fully-Parabolized Prediction of Hypersonic Sonic Boom
Abstract: Hypersonic flight-vehicles create shock and expansion waves that propagate through the atmosphere and are observed on the ground as sonic booms. We present a methodology to predict the near-field aerodynamic pressure and sonic boom signature using approximately 1% of the computational cost relative to fully-nonlinear computational fluid dynamics and state-ofthe-art sonic boom propagation solvers. …
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Codex Arundel
While reading Leonardo da Vinci’s Codex Arundel last evening, I noticed that the Codex had less scholars examining it relative to others. The fluid dynamics of da Vinci have been extensively studied, with entire dissertations dedicated to the subject. I came across a curious drawing that exhibited turbulent flow. The text is written backward in …
Additional Thoughts on Pressure
I am obsessed with pressure, particularly the internal pressure of fluids. Unlike viscosity, it is absent of frictional forces, and it is a key driving force in both human behavior and aerospace flows. Pressure is an essential component of a perfect fluid and appears on the right-hand side of the Navier-Stokes equations. Without pressure, fluid …
A simplified semi-empirical model for long-range low-frequency noise propagation in the turbulent atmosphere
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 …
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. …
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 …
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: