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 …

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 …

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, …

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 …

Andrei Nikolaevich Kolmogorov – A Digital Tribute

http://kolmogorov.com The great Academacian Andrei Nikolaevich Kolmogorov, who pioneered turbulence theory and started the Russian school, has fans overseas (big surprise!). I always wanted to create a website with a collection of his pictures, portraits, important articles, and anything else I could find online or off. Someone of course beat me to it! A recommended …