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. …
Continue reading “AIAA Paper: Fully-Parabolized Prediction of Hypersonic Sonic Boom”
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 …
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 …
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 …
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. …
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 …
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:
This year my research group had a good showing at the Acoustical Society of America, Dec. 2022. I was happy to give a 20 minute talk myself on jet and rocket coherence and loading. My student, Dr. Alex Carr, who is now a Research Aerospace Engineering at NASA reported on his sonic boom predictions. My …
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All our presenters were present and traveled internationally. DNS is the tool of choice for numerical simulations. Theory emerged from results, and I hope that new relations will guide those making turbulence models today. High-order inertial range scaling exponents in incompressible turbulence using generalized extended self-similarityPresenter: Sualeh Khurshid, Massachusetts Institute of Technology, Author: Sualeh Khurshid, …
Abstract: One now famous analytical solution for shock waves was developed by Dr. Theodore Meyer within his Ph.D. dissertation under advisement of Professor Ludwig Prandtl. The original solution relies on analysis via control volume of the equations of motion. This approach has limited future development of analytical solutions for more complex flow-fields. In this presentation, …
Continue reading “APS Presentation – Alternative Analytical Solution for Planar Oblique Shock Waves”
