FAA Federal Aviation Regulations FAR-25 Appendix G, Continuous Gust Design Criteria, requires a continuous turbulent gust analysis for transport aircraft.
The gust PSD function is given in: The von Karman Vertical Gust Spectrum
A Matlab script for generating a continuous gust velocity PSD is given in: Vibrationdata Signal Analysis Package under the Wind & Waves option.
The script has options for both the Dryden and von Karman gust PSDs. The script can also synthesize a time history for the velocity PSD.
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Here are C++ versions:
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