My good friend Thomas D. Norum recently passed away. He worked as a researcher at NASA Langley over most of his career. I knew him starting in 2009 through 2016 while I was working there. He worked as an experimentalist in the jet noise lab of NASA Langley. As an experimentalist, he worked to understand …
Category Archives: Research
Sonic Boom for Lilliputians
Numerical prediction of loudness metrics for N-waves and shaped sonic booms in kinematic turbulence
Abstract, “The effects of a kinematic field of velocity fluctuations on the loudness metrics of two waveforms are examined with a three-dimensional one-way propagation solver. The waveforms consist of an N-wave and a simulated low-boom from NASA’s X-59 QueSST aircraft. The kinematic turbulence is generated using a von Karman composite spectrum, which is dependent on …
AEDC von Karman Facility
On Large-Scale HPC from Viewpoint of Cebeci
One other aspect should be mentioned. When the program was transferred to El Segundo from Santa Monica, I naturally duplicated some runs. The printout was eight-decimal places, I believe. For a number of steps the new and old tab sheets would check exactly. But then after a while there would be a gradual drift; first …
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Experiments in a Large-Boundary Layer Wind Tunnel: Propagation of Noise through the Turbulent Boundary Layer
My Group recently published a paper on a multiyear experiment campaign. We used the National Science Foundation Boundary Layer Wind Tunnel and sent acoustic waves through the boundary layer. We examined how turbulent structures altered the waveforms. The purpose is to create a high quality database available to the community to understand acoustic-turbulent interactions. Zhang, …
The History of the Navier-Stokes Equations
Over the course of a few years I have collected pictures, biographies, and other tidbits about the many famous people who have created, studied, and dedicated their lives to the Navier-Stokes equations. I set it to the music of Carmina Burana of the MIT Choir (Creative Commons). Enjoy!
2022
This semester we are continuing to perform research for DARPA on analytical methods for hypersonic aerodynamics. It is a difficult task. My new students are transitioning well and former students are excelling in their new careers. I am teaching a new course on turbulence modeling. This should be placed online for everyone near the end …
Foundations of Turbulence
The mathematical formulation of the problem of homogeneous turbulence is this: Given an infinite body of uniform fluid in which motions conform to the equations and, and given that at some initial instant the velocity of the fluid is a random function of position described by certain probability laws which are independent of position, to …
Acoular
http://www.acoular.org/ My students and myself have had some good luck with the open source and free software package Acoular. We used it to try and visualize the acoustic source distribution within a tornado. It worked fairly well, but of course the technique is dependent on the quality of data used. This is generated by CFD …